Double-camouflaged tellurium nanoparticles for enhanced photothermal immunotherapy of tumor

Double-camouflaged tellurium nanoparticles for enhanced photothermal immunotherapy of tumor | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Double-camouflaged tellurium nanoparticles for enhanced photothermal immunotherapy of tumor Chaoqing Li, Luyao Yang, Bin Zhang, Jiahao Li, Bingjie Cai, Wei Ni, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4097182/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 08 Oct, 2024 Read the published version in Journal of Nanobiotechnology → Version 1 posted 7 You are reading this latest preprint version Abstract The photothermal conversion properties of tellurium (Te) nanoparticles have been extensively investigated, rendering them a promising candidate for tumor photothermal therapy. However, there is still room for improvement in the development of efficient Te-based drug delivery systems. Here, Te nanoparticles are mineralized with bioactive molecules within attenuated Salmonella (S-Te), which are subsequently taken up by macrophages (RAW264.7) to construct a double-camouflaged delivery platform (RS-Te). Remarkably, RS-Te retains superior photothermal properties under near-infrared irradiation. The mineralization process eliminates bacterial proliferation potential, thereby mitigating the risk of excessive bacterial growth in vivo . Furthermore, the uptake of bacteria by macrophages not only polarizes them into M1 macrophages to induce an anti-tumor immune response but also circumvents any adverse effects caused by complex antigens on the bacterial surface. The results show that RS-Te can effectively accumulate and retain in tumors. RS-Te-mediated photothermal immunotherapy largely promotes the maturation of dendritic cells and priming of cytotoxic T cells induced by near-infrared laser irradiation. Moreover, RS-Te can switch the activation of macrophages from an immunosuppressive M2 phenotype to a more inflammatory M1 state. The double-camouflaged delivery system may offer highly efficient and safe cancer treatment. Tellurium nanoparticles Biomineralization Biomimetic delivery vector Macrophages-mediated immunotherapy Photothermal therapy Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Tellurium nanoparticles (TeNPs) have been used in the photothermal therapy of tumors due to its excellent photothermal conversion properties [ 1 , 2 ]. However, TeNPs still face many problems in biomedical applications, including low tumor aggregation, high systemic clearance, and unsatisfactory biocompatibility. How to safely and efficiently deliver therapeutic nanomaterials to the tumor sites to improve therapeutic outcomes remains a challenge. With more understanding of the bacteria in tumor tissues, bacteria become a promising drug carrier. One of the advantages is that the bacteria can preferentially colonize in the tumor tissues due to the chaotic vasculature, immunosuppression, hypoxia, and eutrophication of solid tumors [ 3 , 4 ]. Subsequently, in situ synthesis of functional nanoparticles by biomineralization and bioreduction using bacteria as bioreactors and vehicles has been vigorously developed, because of bacteria facile cultivation, rapid proliferation, and high bioactivity. For example, Zhang et al. utilized Escherichia coli MG1655 and Shewanella oneidensis MR-1 as bioreactors to synthesize gold and palladium nanoparticles on their surface and achieve tumor-targeting augmenting PTT and photothermal-controlled cytokine therapy [ 5 ]. However, surface modifications by bacteria may allow drug molecules to leak prematurely, increasing unknown risks. With the assistance of bioactive molecules, bacteria could convert absorbed inorganic ions into nanoparticles without affecting their surface characteristics [ 6 ]. It has been reported that tellurium nanoparticles (TeNPs) could be synthesized in a variety of bacteria [ 7 ]. Therefore, the synthesis of Te within bacteria was expected to be used in highly effective therapy of tumors. The inherent immunogenicity of bacteria may cause strong cytokine storms and fatal side effects during circulation in the body, which makes researchers more cautious about using bacteria-mediated therapies [ 8 ]. The surface of E.coli strain CFT073 was biomimetically mineralized with a metal-organic framework (MOF) by Gassensmith's group [ 9 ]. The encapsulation process prevented the premature exposure and destruction of bacterial surface antigens. Liu's group reported a camouflaged strategy to generate stealth bacteria by simply extruding erythrocyte membranes with bacteria, which minimizes the inflammatory reaction and side effects [ 10 ]. Cancer cell membranes have also been adopted to improve the performance of nanoparticle therapeutics in our previous work [ 11 ]. It is worth noting that the extraction of cell membranes could more or less destroy the function of membranes. Compared to the cell membrane fragments, holistic cells have exquisite sensitivity and specificity, allowing them to sense diverse signals, move to specific sites in the body, and execute complex response behaviors [ 12 , 13 ]. Macrophages are the major tumor-infiltrating immune cell population with a critical role in regulating tumor progression, M1 macrophages secrete immunogenic cytokines, such as IL-12 and TNF-α, improve the immune response inhibiting effects on tumor growth [ 14 , 15 ]. Therefore, blocking bacteria with macrophages may be a very promising strategy for reducing bacteria-induced adverse reactions. Herein, we present the development of a novel macrophage-mediated double-camouflaged delivery system (RS-Te) for enhanced photothermal immunotherapy in cancer treatment (Scheme 1 ). TeNPs are synthesized within attenuated Salmonella (Sal, VNP 20009) by biomineralization (S-Te), and the S-Te are uptaked subsequently by macrophages. The macrophages are polarized into M1 macrophages under the action of bacteria, which possess both immunotherapeutic and tumor-homing properties. Biomineralization-induced inhibition of bacterial proliferation enhances safety in vivo while preserving bacterial antigens. Our results demonstrate efficient accumulation and retention of RS-Te in tumors. Compared to laser-free irradiation, NIR laser irradiation induces a more potent therapeutic immune response by promoting dendritic cell (DC) maturation and enhancing cytotoxic T cell priming. Moreover, RS-Te reprograms tumor-associated macrophages (TAMs) to remodel the immunosuppressive tumor microenvironment by increasing the M1/M2 ratio. These immune responses optimize photothermal therapy efficacy, leading to eradication of malignant tumors and suppression of tumor metastasis. This bionic double-camouflage strategy provides innovative insights for achieving more efficient and safe drug delivery in synergistic tumor therapy. Experimental Materials Na 2 TeO 3 , Cy5.5, calcein-AM, and propidium iodide (PI) were obtained from Aladdin (Shanghai, China). Lysozyme, DAPI, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI), lipopolysaccharide (LPS), cell counting kit-8 (CCK-8), and BCA protein assay kit were purchased from Beyotime Biotechnology (Shanghai, China). Dulbecco's Modified Eagle's Medium (DMEM), and PBS were obtained from HyClone (Logan, Utah, USA). Penicillin-streptomycin, FBS, and trypsin were purchased from Gibco Life Technologies (Grand Island, NY, USA). PE-conjugated anti-mouse CD86, PE-conjugated anti-mouse CD80, PE-conjugated anti-mouse CD206, FITC-conjugated anti-mouse CD11b, APC-conjugated anti-mouse CD3, PE-conjugated anti-mouse CD8, FITC-conjugated anti-mouse CD4, PE-conjugated anti-mouse MHC-II anti-mouse MHC-II antibody, and purified anti-catalase antibody were purchased BioLegend (USA). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) loading buffer and tumor-infiltrating tissue lymphocyte separation kit were purchased from Beijing Solarbio Science & Technology (China). BALB/c female mice were purchased from Beijing Vital Laboratory Animal Technology Co., Ltd. (Beijing, China). Characterizations The morphologies of samples were checked by a transmission electron microscope (TEM, HT7700, Hitachi, Japan). TEM-assisted element mapping imaging was conducted on a Talos F20× atomic resolution analytical microscope (PEI, Netherlands). X-ray diffractometry (XRD) spectrum was conducted by a PANalytical B.V., Netherlands. The sizes and zeta potentials of probes were obtained on a ZS90 Zeta Sizer (Malvern, UK). The fluorescence imaging of cells was obtained by a confocal laser scanning microscope (CLSM, FV3000, Olympus, Japan). The flow cytometry (FCM) was conducted by an FC500 flow cytometry (Beckman Coulter, USA). The in vivo and in vitro fluorescence imaging were realized by a small animal fluorescence imaging system (IVIS Spectrum, PerkinElmer). The light sources of photothermal experiments were used by an MDL-III-808-2.5 W laser (Changchun New Industries Optoelectronics Tech. Co. Ltd., China). Infrared thermal images were recorded by an EasIR-9 thermal imager (Wuhan Guide Infrared Co., Ltd., China). Preparation of RS-Te VNP20009 Sal was cultured in Luria-Bertani (LB) broth (10 g/L tryptone, 5 g/L yeast extract, and 10 g/L NaCl) at 37°C. For S-Te synthesis, Na 2 TeO 3 (0.8 mM) was added into 30 mL of bacterial suspension (2×10 9 CFU/mL) and the mixture was incubated in a shaking incubator (37°C, 220 rpm) for 4 h. The black S-Te was obtained by centrifugation at 5000 rpm for 5 min, then washed three times and stored at 4°C. S-Te (1×10 5 CFU/mL) was incubated with RAW264.7 cells in 6-well plate for 2 h at 37°C in an incubator with 5% CO 2 to obtain RS-Te. The RS-Te were washed three times and digested, resuspended in PBS, and stored at 4°C. Preparation dead Sal To obtain dead Sal, cultured Sal was collected, washed, resuspended in PBS, and inactivated by pasteurization for 30 min at 70°C. Preparation of TeNPs The prepared S-Te was treated with lysozyme and ultrasonic homogenizer (Scientz, Ningbo, China). The supernatants were centrifugated three times at 8000 rpm for 5 min. TeNRs were resuspended in PBS and stored at 4°C. Photothermal property study Absorption spectra of various concentrations of RS-Te (Te concentration: 10, 20, 30, and 40 µg/mL) in PBS were acquired by a UV-2550 visible Spectrophotometer (Shimadzu, Japan). RS-Te suspensions (300 µL) of different concentrations (Te concentration: 10, 20, and 40 µg/mL) were irradiated by 808 nm laser (1.5 W/cm 2 , 10 min), and the temperature of suspensions was recorded by an infrared thermal camera. RS-Te suspensions (40 µg/mL) was irradiated by 808 nm laser at different power densities (0.75, 1.0, and 1.5 W/cm 2 ) for 10 min, and the temperatures and infrared thermal images were recorded. The photothermal performances of S-Te, TeNPs, and dead Sal at Te concentration of 40 µg/mL were studied with irradiation of 808 nm laser at 1.5 W/cm 2 for 10 min. Photothermal stability of RS-Te was studied under the above conditions over five cycles of alternating heating and cooling. The photothermal conversion efficiency ( η ) of mPT was calculated by the following formula: where hs = mc / τ , Q Dis = hs × ( T max of water − T surr ), m was the mass of solution (g), c was specific heat of water (J/g•°C), I was laser power (W) and A 808 was absorption at 808 nm. Cell culture Murine breast cancer 4T1 cells and murine RAW264.7 macrophages were purchased from Type Culture Collection of the Chinese Academy of Sciences (Shanghai, China). 4T1 cells and RAW264.7 macrophage cells were cultured in DMEM medium supplemented with 10% FBS, penicillin (100 U/mL), and streptomycin (100 µg/mL) at 37°C in a 5% CO 2 incubator, respectively. M2 macrophages were obtained by stimulating RAW264.7 cells with IL-4 (20 ng/mL) for 24 h. Murine bone marrow-derived DCs (BMDCs) were obtained by culturing bone marrow cells in RPMI 1640 complete medium with addition of GM-CSF (10 ng/mL) and IL-4 (10 ng/mL) for 7 days. Cellular uptake assay RAW264.7 cells were incubated with GFP-marked S-Te at the concentration of 20 µg/mL Te for 2 h to obtain RS-Te. Then, the cells were rinsed with PBS three times, fixed with 4% paraformaldehyde solution for 20 min, and stained with DAPI (1 µg/mL) for 5 min. The cells were observed by FV3000 CLSM. Preparation of RS-Te was further studied via TEM. The RS-Te were fixed with 2.5% glutaraldehyde solution, and collected for TEM sample preparation. The cells were observed by TEM. Western blot Bacteria and cells were harvested and disrupted using sonication and the supernatants were collected. All protein samples were subjected to 12% SDS-PAGE and transferred to polyvinylidene fluoride membranes. Cytotoxicity of RS-Te To evaluate the cytotoxicity of RS-Te in vitro , 4T1 cells were treated with different conditions, including PBS, dead Sal, S-Te, RS-Te, and TeNPs with or without laser for 12 or 24 h. Then, the cell viability was measured by CCK-8 assay. In vitro macrophage analysis RAW264.7 cells were seeds into 24-well culture plates at a density of 1×10 5 per well and incubated overnight at 37°C, followed by the treatment of IL-4 for 48 h to induce the M2 polarization. Then, M2 macrophages were treated with PBS, TeNPs, S-Te, RS-Te, dead Sal, and LPS (100 ng/mL) at the same concentration (Te concentration: 20 µg/mL). After incubation for 12 h, cells were harvested, and the expression of M1 macrophage-related marker CD86, MHC-II, and inflammation-related cytokines (TNF-α, IL-12, TGF-β, and IL-10) were analyzed. In vitro and in vivo DCs maturation 4T1 cells were treated with dead Sal, TeNRs, S-Te, and RS-Te at the same concentrations (Te concentration: 20 µg/mL) for 2 h. Then, the cells were treated with or without laser irradiation (808 nm, 1.5 W/cm 2 , 5 min). The culture supernatants and debris of 4T1 cells in different groups were added into immature BMDCs, respectively. After incubation for another 24 h, the cells were collected, and stained with fluorescence-labeled anti-CD11b, anti-CD80, anti-CD86, anti-CD206, and anti-MHC-II antibodies. The stained cells were analyzed by FCM. Transwell model was established to analyze the DCs maturation in vitro . Murine BMDCs from marrow cavities of femurs and tibias of mice were cultivated in plates with a medium containing 20 ng/mL GM-CSF and 20 ng/mL IL-4 7 days after, BMDCs were seeded in the lower chamber of transwell plates at a density of 5×10 5 per well. 4T1 cells were seeded in the upper chamber of transwell plates at a density of 5×10 5 per well, following the treatment of PBS, LPS (100 ng/mL), RS-Te, or RS-Te plus laser (Te concentration: 20 µg/mL). After administration for 24 h, the BMDCs were collected, the TNF-α and IL-6 in supernatants were analyzed and BMDCs were suspended with PBS containing PE-conjugated anti-mouse CD80, PE-conjugated anti-mouse CD86, and PE-conjugated anti-mouse MHC-II by FCM. For in vivo DCs stimulation experiments, female Balb/c mice were subcutaneously injected with PBS, S-Te, and RS-Te ( n = 4, Te concentration: 20 µg/mL). At 24 h after administration, the mice were sacrificed, and cells were collected from the inguinal lymph nodes for analysis by staining with fluorescence-labeled anti-CD11b, anti-CD80, anti-CD86, anti-CD206, and anti-MHC-II antibodies. In vivo biosafety The mice (female, SPF, 5 weeks) were intravenously injected with Sal, S-Te, and RS-Te (Te concentration: 1 mg/kg), another RS-Te group was irradiated by laser, and PBS group as control. The body weight and temperature of mice were recorded every day for 24 days. Serum and anticoagulant blood were collected on days 0.5, 1, and 14 for blood biochemistry (ALT and AST for liver function, BUN and CREA for kidney function, and CRP for inflammation and infection) and blood routine examination (WBC, RBC, and PLT), respectively. In vivo photothermal performance and antitumor activity When the tumor reached 90 mm 3 , 4T1 tumor-bearing Balb/c mice (5 weeks) were randomly divided into 4 groups (4 mice of each group), including: (I) PBS, intravenously injected with 200 µL of PBS; (II) PBS + L, intravenously injected with 200 µL of PBS, at 24 h post-administration, the tumors were irradiated with 808 nm laser for 10 min at power densities 1.5 W/cm 2 ; (III) RS-Te, intravenously injected with 200 µL of RS-Te suspension, (Te concentration: 1 mg/kg); (IV) RS-Te, intravenously injected with 200 µL of RS-Te suspension, (Te concentration: 1 mg/kg), at 24 h post-administration, the tumors were irradiated with 808 nm laser for 10 min at power densities 1.5 W/cm 2 . The body weight of the mice and the length and width of the tumor were recorded every two days. The volume of tumor was monitored during the observation period as follows: V = W 2 × L /2, where W and L were the length in minor and major axes, respectively. The mice were sacrificed on the 24th day, the tumors were harvested and weighed. The major tissues of mice were collected and stained by H&E. In vivo immune response 4T1 tumor-bearing mice (five weeks, female) were randomly divided into four groups (four mice/per group). The mice were intravenously injected with PBS, S-Te, and RS-Te, after 24 h postinjection, another group of RS-Te was treated with laser irradiation (1.5 W/cm2, 10 min). At 48 h post-administration, the mice were sacrificed, and Tumor-draining lymph nodes (DLNs) and tumors were harvested for analysis of immune responses. The tumors were cut into pieces and digested with DMEM medium containing 0.8 mg/mL collagenase I for 40 min at 37°C. The digested tumors were ground by a syringe plunger on a 40 µm cell strainer to generate single-cell suspensions. Single-cell suspensions of DLNs were directly obtained by mashing the tissues through a 40 µm cell strainer. For T cell analysis, the cells were stained with CD3, CD4, and CD8 antibodies. For Treg analysis, cells were stained with CD4 and Foxp3 antibodies. For M1 macrophages analysis, cells were stained with CD11b and CD86 antibodies. For M2 macrophages analysis, cells were stained with CD11b and CD206 antibodies. Then, stained cells were washed with PBS three times and measured by FCM. Statistical analysis Statistical analyses were conducted and the results were presented as mean ± standard deviation. 2-tailed Student's t-test or one-way analysis of variance was utilized to determine statistical significance between two or more groups, respectively. The significance of difference was indicated as (ns: no significance, * P < 0.05, ** P < 0.01, and *** P < 0.001). Results and discussion Fabrication and characterization of RS-Te The sodium tellurite (Na 2 TeO 3 ) was added into the medium during the culture of Sal, and rod-like nanostructures were observed inside Sal by TEM (Fig. 1 A). Meanwhile, the color of Sal suspension turned to black (Additional file 1: Fig. S1 ), which may be attributed to the reduction of Te oxyanions via the intracellular glutathione (GSH), reduced nicotinamide dinucleotide phosphate and GSH reductase in Sal and the spontaneous decomposition of the obtained Te precursor (GSTeH) [ 16 ]. A large number of Sal could be found in the RAW264.7 cell by TEM after incubating the S-Te (Fig. 1 B), and the TeNPs in the Sal could also be clearly observed through magnified TEM (Fig. 1 C). The elements composition and distribution of RS-Te were analyzed by elemental mapping images, containing Te and elements from Sal (P, S, and N) (Fig. 1 D). After the macrophages and Sal with green fluorescent protein (GFP) were co-cultured, bright green fluorescence was observed in a large number of RAW264.7 cells, suggesting successful uptake of the Sal by the RAW264.7 cells (Additional file 1: Fig. S2). To further characterize the bacterial uptake behavior of macrophages, the RAW264.7 cell membrane was labeled with a red fluorescent dye (DiI), and the nucleus was located via 4',6-diamidino-2-phenylindole (DAPI, blue fluorescence). The GFP was visually observed in the RAW264.7 cells by CLSM (Fig. 1 E), indicating that Sal was successfully taken up by RAW264.7 cells. The XRD pattern of Te from RS-Te matched well with the standard diffraction pattern (JCPDS No. 36-1452) of hexagonal Te, in which the diffraction peaks of Te could be indexed to (100), (101), (110), (201), and (113) (Fig. 1 F). The valence state of Te from RS-Te was analyzed by X-ray photoelectron spectroscopy. As shown in Fig. 1 G, the characteristic peaks at binding energies of 572.9 and 583.0 eV were assigned to Te 3d 5/2 and Te 3d 3/2 of Te 0 , while the characteristic peaks at binding energies of 575.5 and 585.9 eV were assigned to Te 3d 5/2 and Te 3d 3/2 of tellurium oxide, which might be attributed to the easily-occurred tellurium oxide in natural environment [ 17 ]. Compared to the size of a single RAW264.7 cell, there was no significant change observed in the size of RS-Te (Additional file 1: Fig. S3A), and the surface charges of both the single RAW264.7 cell and RS-Te were found to be comparable (Fig. 3 B). These findings suggest that RAW264.7 cells maintained their integrity after internalizing Sal-containing Te. In addition, SDS-PAGE (Fig. 1 H) analysis showed that RS-Te had similar protein bands compared with the profile of S-Te and single RAW264.7 cell, indicating that the surface proteins of the Sal were still present after the Sal were ingested by RAW264.7 cells. The result is helpful for the activation of the immune response in vivo . Studies have shown that tellurates and tellurites are toxic, and they could inhibit bacterial growth [ 18 ]. As demonstrated in Additional file 1: Fig. S4A, with the increase of Na 2 TeO 3 concentration, the absorption value (OD 600 ) of Sal gradually decreased, and a concentration of 0.8 mM had a significant inhibitory effect on Sal growth. When the above samples were further diluted (1×10 4 ) and cultured on the solid LB plates, that the Sal multiplication ability was significantly inhibited compared with the untreated group (Additional file 1: Fig. S4B). These results showed that the mechanism of cytoplasmic synthesis of TeNPs in Sal might be related to the detoxification of tellurates and tellurites, by generating Te 0 and tellurium oxide with less toxicity. To balance high biomineralization efficiency and low proliferation rate, the 0.8 mM Na 2 TeO 3 was chosen for the preparation of the S-Te. Photothermal properties of RS-Te Rod-like TeNPs based on polypeptide-mineralization have shown to have excellent photothermal conversion and tumor ablation capabilities in our previous work [ 19 ], and it was reported that PTT elicited immunogenic cell death (ICD) by inducing dying tumor cells to release damage-associated molecules [ 20 ]. The UV-vis-NIR absorption spectra of Te showed that Te presented a wide light absorption spectrum, which is positively correlated with the concentration of Te (Fig. 2 A). To explore whether the biomineralized S-Te has acceptable photothermal properties, a thermal imager was introduced to record the temperature changes of the different concentrations of S-Te under NIR laser irradiation (808 nm, 1.5 W/cm 2 ). As shown in Fig. 2 B, Te concentrations in S-Te suspensions are positively correlated with temperature increases. The corresponding quantitative data are shown in Fig. 2 C. Upon irradiation with an NIR laser, the temperature of S-Te suspension at Te concentration of 40 µg/mL increased by 35.8°C, while water only slightly increased by 4.3°C. Under NIR laser irradiation for 10 min, the temperature changes of S-Te (40 µg/mL) at different power densities (0.75, 1.0, and 1.5 W/cm 2 ) were measured to be 16.7, 23.4, and 33.8°C, respectively, suggesting a power density-dependent photothermal effect of S-Te (Fig. 2 D). These obvious temperature changes provided favorable conditions for in vivo applications of S-Te. In addition, S-Te exhibited a similar temperature rise as TeNPs from Sal at the same condition, while dead Sal and water showed negligible temperature changes. The results reveal the photothermal property from TeNPs rather than bacteria in photothermal heating of S-Te (Fig. 2 E). It is worth noting that there was little difference between the temperature changes of the RS-Te and S-Te upon NIR laser irradiation (Te: 40 µg/mL, 808 nm, 1.5 W/cm 2 ), indicating that the double-camouflaged strategy had little effect on the photothermal properties of the delivery platform (Fig. 2 F). It was found that the temperature curve was an inappreciable change after 5 repeated irradiation cycles, revealing the remarkable photothermal conversion stability of RS-Te (Fig. 2 G). Moreover, the time constant ( τ s ) was measured to be 219.36 s, and photothermal conversion efficiency was calculated to be 33.8% ( η ), which is higher than that of common photothermal nanoagents in the PTT (Fig. 2 H, I), such as Au nanorods (22%), CuS nanoparticles (28.8%), and Pd nanosheets (30.9%) [ 21 – 23 ]. Together, these results indicate the superior NIR photothermal performance and high photostability of RS-Te, implying its potential for PTT of tumors. In vitro immune stimulation performance induced by RS-Te-triggered PTT As one of the key immune cells involved in cancer immunity, macrophages are one of the most abundant circulating cells in the body [ 24 ]. To investigate whether biomineralized S-Te could polarize macrophages into M1 macrophage cells, FCM was introduced to analyze the ratio of M1 and M2 in macrophage samples after different treatments. As shown in Fig. 3 A, an significant increase of the macrophages M1/M2 rations was found in raw macrophages incubated with S-Te, RS-Te, dead Sal, and LPS (the positive control), while the update in the TeNPs group was negligent comparing with the untreated group, which implies that the Sal played a key role in the polarization of macrophages. Furthermore, the proportional ratio increase of M1/M2 macrophages in the RS-Te group might be caused by secreting chemokines by RS-Te this chemokines induce macrophage polarization. To further investigate the effect of RS-Te on TAMs remodeling, IL-4-conditioned RAW264.7 cells (M2 macrophages) were incubated with PBS, TeNPs, RS-Te, S-Te, and LPS for 12 h (Fig. 3 B). The proportion of M1/M2 was significantly increased in the S-Te, RS-Te, dead Sal, and LPS groups compared with the TeNPs and PBS groups. Correspondingly, the mean fluorescence intensity (MFI) of CD86 + (M1 macrophage marker) significantly increased in S-Te, RS-Te, dead Sal, and Sal groups compared with PBS and TeNPs groups (Fig. 3 C). Besides, the secretion of proinflammatory factors, such as TNF-α and IL-12, markedly increased in IL-4-conditioned RAW264.7 cells (Additional file 1: Fig. S5A, B). The contents of M2 macrophage-related cytokines in the samples were also detected by FCM, such as TGF-β and IL-10. Moreover, their levels were found to be significantly decreased in the S-Te, RS-Te, dead Sal, and LPS groups (Additional file 1: Fig. S5C, D), suggesting an effective polarization from the M2 phenotype to the M1 phenotype. Antigen-presenting cells (APCs) play a key role in the initiation and regulation of innate and adaptive immune responses. Once exposed to antigens, the immature DCs transform into maturation for antigen processing and presenting [ 25 ]. Therefore, DCs maturation induced by RS-Te was analyzed by FCM to measure the expression levels of co-stimulatory molecules (CD80, CD86, and MHC-II). Compared with the PBS group, the expression levels of CD80 + CD86 + in BMDCs incubated with dead Sal and S-Te increased 2.52 and 2.47 times, respectively. However, no obvious change was found when BMDCs incubated with TeNPs, indicating that it was Sal in S-Te that promoted the maturation of DCs in vitro (Fig. 3 D). It is worth noting that the expression levels of CD80 + CD86 + in the RS-Te group were 1.67 times higher than that of the S-Te group, which might be due to the fact that RS-Te enriched with more Sal and that the polarized RS-Te further matured the BMDCs by secreting related cytokines. The expression levels of MHC-II also presented a similar trend in BMDCs with different treatments (Fig. 3 E). To investigate whether RS-Te-trigged PTT maturate DCs in vitro , supernatants and 4T1 cell debris after various treatments were collected and incubated with BMDCs for 12 h. As shown in Fig. 3 F, G, compared with the control group, supernatants and 4T1 cell debris incubated with either S-Te or RS-Te could induce higher expression of CD80 + CD86 + and MHC-II of BMDCs, whether plus or not. These results indicate that the bacteria and M1 macrophage could act as immune adjuvant for DC maturation induction. For all groups with laser irradiation, DC maturation could be further promoted. In particular, BMDCs in 4T1 + RS-Te + Laser group exhibited the highest expression of CD80 + CD86 + and MHC-II among all groups, indicating that ICD induced by photothermal was another major player for DCs maturation. Moreover, the transwell models were established to simulate RS-Te-triggered PTT in TME. 4T1 cells were cultured in the upper chamber and BMDCs were cultured in the bottom chamber (Fig. 3 H). Then, the upper chamber was separately treated with PBS, LPS, RS-Te, and RS-Te + Laser. The FCM assay results show that RS-Te, and RS-Te + Laser treated BMDCs significantly increased the expression of costimulatory molecules, including CD86 and MHC-II (Additional file 1: Fig. S6A, B). Correspondingly, the secretion of proinflammatory factors, such as TNF-α and IL-6, also increased (Additional file 1: Fig. S6C, D). In particular, after NIR laser irradiation, the levels of TNF-α and IL-6 in the RS-Te + Laser group were 2.18 and 2.33 times higher than that of the RS-Te group, respectively. Considering the importance of the role of MHC molecules in antigen presentation and impressive ICD induced by RS-Te, RS-Te-triggered PTT has a great advantage in synergistically enhancing tumor immunotherapy. To further explore whether RS-Te could stimulate DCs maturation in vivo , the inguinal lymph nodes from healthy mice are collected after 24 h subcutaneous injection of RS-Te. The percentages of mature DCs in inguinal lymph nodes showed a significant elevation compared with the control group (Fig. 4 A, B), which confirms the ability of RS-Te to stimulate DCs maturation in vivo . All of the results imply that RS-Te could transform M2 macrophages into M1 macrophages, and has the potential to remodel the immunosuppressive TME and promote antitumor immune responses. Antitumor effects and immune responses of RS-Te-mediated photothermal immunotherapy in vitro As shown in Fig. 3 D, E, RAW264.7 remained active after incubating the S-Te. The live/dead cells were respectively stained by calcein-AM (green fluorescence) and PI (red fluorescence) to evaluate the viability of RAW264.7 cells, untead RAW264.7 cells as a control (RAW), macrophages were incubated with Sal, S-Te, and LPS as RS, RS-Te, and RL groups, respectively. As shown in Fig. 4 C, no red fluorescence was observed after different treatments, confirm the specificity of RS-Te. After incubating the above supernatant with 4T1 cells, the results of the CCK-8 experiment showed that the cell viability decreased to a certain extent in RS, RS-Te, and RL groups compared with the PBS and RAW groups, suggesting RS-Te secretion had tumor cells killing effect (Fig. 4 D). Follow more, RS-Te was examined in vitro . As shown in Fig. 4 E, 4T1 cell viabilities decreased to 73.8% after incubation with RS-Te for 24 h, compared with the 4T1 cells incubated S-Te. The results show that RS-Te could retain its normal activity and kill cancer cells, which is consistent with the previous results (Fig. 3 D, E). 4T1 cells exhibited high viabilities after incubation with TeNPs, Dead + Sal, Dead + Sal + laser, and S-Te, while 4T1 cell viabilities significantly decreased at TeNRs plus laser, S-Te plus laser, and RS-Te plus laser groups for 24 h (Te concentration: 30 µg/mL). The results indicate that it was the photothermal conversion ability of TeNPs that caused the temperature hike, led to cell death. Especially, compared with the S-Te + laser group, the 4T1 cell viability decreased to 8.03% after 4T1 cells were incubated with RS-Te plus laser for 24 h. These results show the prominent photothermal therapeutic efficacy of RS-Te under NIR irradiation. In vivo tumor targeting and biodistribution of RS-Te To validate the tumor-homing ability of RS-Te, subcutaneous 4T1 tumor-bearing mice models were established, and the NIR fluorescence dye Cy5.5-labeled RS-Te was employed for the real-time fluorescence monitoring of in vivo biodistribution and metabolism for a long time. The corresponding results are illustrated in Fig. 5 A. After intravenous injection of the RS-Te (Te concentration: 1.0 mg/kg), the fluorescence signal of the tumor site gradually increased, and reached to peak at 24 h, showing the excellent tumor retention capacity of RS-Te. The fluorescence signal quantization results of the tumor site in Fig. 5 B are consistent with those observed above. Blood samples were then collected at different time points, and Te concentrations were measured to determine how the RS-Te metabolized in vivo over time. As shown in Fig. 5 C, less RS-Te accumulated in the heart, which avoided the risk of acute toxicity by Te [ 26 ]. Especially, a fairly high concentration of Te was detected at the tumor site, verifying that RS-Te administered systemically could efficiently accumulate and retain in tumors. These data verified that the prepared RS-Te possessed high tumor-homing ability. Thanks to gratifying enrichment ability, the in vivo photothermal properties of RS-Te were verified by NIR laser irradiation at the tumor site after 24 h intravenous injection of RS-Te and PBS. The thermal imaging data (Fig. 5 D) revealed that a significant temperature increase of the tumor site could be observed after NIR laser irradiation for 10 min (808 nm, 1.5 W/cm 2 ). The temperature changes in the tumor site are recorded (Fig. 5 E), the temperature of the tumor site rose rapidly within 4 min and reached 59.3°C after 10 min irradiation with NIR laser, indicating RS-Te possessed excellent photothermal conversion properties in vivo . Enhanced biosafety of RS-Te To assess the biocompatibility and biosafety of RS-Te, the physiological and biochemical changes were monitored in healthy mice by intravenously injecting RS-Te at a Te concentration of 1.0 mg/kg. As demonstrated in Additional file 1: Fig. S7A, administration of S-Te, RS-Te, and RS-Te + Laser induced slight weight loss and the weight loss was gradually recovery in 14 days, while all mice receiving the Sal all died within 48 h. This is possibly due to the rapid proliferation of Sal in the body. The body temperature of the mice treated with S-Te, RS-Te, and RS-Te + Laser slightly dropped and back to normal within 4 h, while the Sal-treated mice showed a significant decrease in body temperature (Additional file 1: Fig. S7B). Moreover, blood biochemistry and routine examinations were carried out at 0.5, 1, and 14 days after intravenous injection. The mice in the Sal group had died after 1 day, so the data were no longer recorded (Fig. 6 ). Following the injection of S-Te, there was a sharp increase of liver function marker ALT and AST and kidney function marker BUN and CRE in the serum levels on the 1st day (Additional file 1: Fig. S9B-E). Also, a spike of CRP concentration was detected on the 1st day after treatment with S-Te, manifesting the occurrence of inflammation or infection (Fig. 6 F). Compared to the PBS group, these markers were slightly elevated in the RS-Te group and gradually backed to normal within 14 days, this could be an indicator that the macrophage modification strategy greatly reduced the risk of bacterial infection and significantly improved the biosafety of the delivery vector. The trend of blood biochemistry and routine indexes change in RS-Te + Laser were similar to that of the RS-Te group, indicating that laser treatment did not cause serious body damage. Overall, the system of S-Te delivery by RS-Te significantly enhanced the safety and potential for in vivo applications. Antitumor effects and immune responses of RS-Te-mediated photothermal immunotherapy in vivo Spurred by the prominent photothermal conversion and immune response feature of RS-Te in vitro , the in vivo antitumor effects of intravenously injected RS-Te upon NIR irradiation were evaluated. 4T1 tumor-bearing mice (5 weeks, female) were randomly divided into 4 groups (4 mice/per group). At 24 h post systemic administration of PBS or RS-Te via tail vein, the mice were illuminated with or without NIR laser irradiation (1.5 W/cm 2 , 10 min), and the 4 groups were denoted as PBS, PBS + Laser (PBS + L), RS-Te, and RS-Te + Laser (RS-Te + L) groups, respectively. Tumor growth was barely inhibited in the PBS and PBS + L groups (Fig. 7 A). Although tumor growth was slower in the RS-Te group compared with the PBS and PBS + L groups, the tumor volume reached to 659.87 cm 3 during the observation period. On the contrary, after NIR laser treatment, tumors in the RS-Te + L group were almost eliminated. The tumor growth status is shown in Fig. 7 B. On day 24, all mice were euthanized, and the tumors were collected and photographed (Fig. 7 C). The mean tumor weight in each group was calculated (Fig. 7 D). The tumor volume and weight were comparable with monitoring data. Moreover, the H&E, Ki67, and TUNEL staining showed that the RS-Te + L group initialized the most potent apoptosis effect and the lowest proliferation of tumor cells (Fig. 7 E). Those results indicated that the RS-Te had excellent PTT ability. The other groups showed a slight body weight loss within two days of different treatments except for the PBS group. This may be explained by mice's excessive stress response, and the body weight of mice gradually recovered and gained a slight amount of weight (Fig. 7 F). At the end of treatment, the major organs of mice were sectioned and analyzed (Fig. 7 G). The tissue structure of the PBS, RS-Te, and RS-Te + L groups was similar to that of the PBS group, and no obvious structural damage was observed, which confirms the safety of the RS-Te. Since tumor nodules were found in the PBS group but not in the RS-Te + L group, we further carred out H&E staining for the lungs tissue of each group (Additional file 1: Fig. S8). Compared with the large number of tumor nodules in the lungs in the PBS group, the tumor nodules were significantly smaller after intravenous injection of RS-Te and NIR laser irradiation, indicated that RS-Te plus laser treatment possessed strong anti-tumor metastasis potential. To elucidate the mechanism of tumor elimination and anti-tumor metastasis triggered by RS-Te-based phototherapy, 4T1 tumor-bearing mice (five weeks, female) were randomly divided into 4 groups (4 mice/per group). The mice were intravenously injected with PBS, S-Te, and RS-Te, after 24 h post injection. Another group of RS-Te was treated with laser irradiation (1.5 W/cm 2 , 10 min), denoted as PBS, S-Te, RS-Te, and RS-Te + L groups, respectively. DLNs and tumors of mice were collected and analyzed by FCM at 48 h after administration. It is shown that intravenous administration of RS-Te induced the more pronounced proliferation of DCs maturation in DLNs compared with administration of S-Te, indicating that the delivery system of macrophages carrying mineralized bacteria had a stronger immune activation capacity than that of bacterial vectors alone (Additional file 1: Fig. S9). More importantly, RS-Te plus laser treatment led to further DC maturation, and a similar trend of mature DC proportion was observed in tumors of each group, illustrating that the combination of Te-based photothermal killing and biomimetic strategy could synergistically contribute to DC maturation (Additional file 1: Fig. S10). The population of tumor-infiltrating effector T lymphocytes (CD3 + CD4 + T cells and CD3 + CD8 + T cells) in total T cells and Tregs in the tumor tissues after treatments were measured. As shown in Fig. 7 H, although the level of CD3 + CD8 + T cells in S-Te group was elevated relative to the PBS group, the level of CD3 + CD8 + T cells increase was more significant in RS-Te and RS-Te + L groups, where the level of CD3 + CD8 + T cells in RS-Te + L group was 4.84, 2.54, and 1.32 times higher than that of the PBS, S-Te, and RS-Te groups, respectively. A similar change trend of CD3 + CD4 + T cells in tumor tissues was also found (Fig. 7 I). In contrast, Tregs that play an important role in immune suppression showed a 5.64-fold reduction relative to the PBS group (Fig. 7 J). Moreover, the level of TAMs in tumors was confirmed by measuring the protein markers from macrophage cell surfaces, including CD80 + CD86 + and CD80 + CD206 + . As shown in Fig. 7 K, L, RS-Te treating boosted the percentage of CD80 + CD86 + with a rate of 17.03%, which was 12.05% in the PBS group and 14.69% in the S-Te group. It is also observed that RS-Te plus NIR laser treatment caused the highest proportion (22.98%) of CD80 + CD86 + , which might be Sal, such as by carrying shRNA against a critical gene of metastasis or upregulating tumor genes, expressing effector proteins, such as IFN-γ [ 27 ]. The IFN-γ was subsequently examined, and the level of IFN-γ obviously increased in the RS-Te + laser group (Fig. 7 M). In addition, the serum levels of TNF-α and IL-6 in the RS-Te + laser group were also remarkably aggrandized (Fig. 7 N, O), which are consistent with the in vitro results. All these results verify that RS-Te could efficiently reprogram the immunosuppressive TME and induce strong CD8 + and CD4 + T cells immune response, attributing to the significantly augmented macrophage polarization, in situ tumor-associated antigens (TAAs) release and presentation, and pro-inflammatory factor regulation, and these responses were further reinforced under NIR laser irradiation. Conclusions In our study, RAW264.7 cells served as a carrier for Sal, providing protection against the host immune system and facilitating targeted delivery of Sal to the tumor core. Additionally, macrophage-camouflaged bacteria effectively evaded adverse immune reactions that would occur with bacteria alone. TeNPs were mineralized within Sal, thereby inhibiting bacterial proliferation and reducing potential safety hazards associated with bacterial multiplication. Moreover, TeNPs exhibited excellent photothermal conversion properties and enabled effective photothermal elimination of tumors. In vivo experiments demonstrated that this double-camouflaged delivery system exposed TAAs through NIR-triggered PTT, stimulated DCs maturation using TAAs, Sal, and M1 macrophages, promoted cytotoxic T cell priming and infiltration into tumors, reprogrammed TAMs, reversed the immunosuppressive tumor microenvironment to antitumor immunity. This RS-Te delivery platform achieved a perfect balance between safety and therapeutic efficacy by utilizing an autogenous vector for the bacterial immune adjuvant. Overall, the RS-Te platform enhanced tumor targeting efficiency and therapeutic effects while improving safety aspects in cancer treatment through synergistic interactions among immune cells, bacteria, and inorganic nanomaterials. Declarations Ethics approval and consent to participate All animal experiments were approved by the Animal Experimental Ethics Committee of Hubei University of Chinese Medicine (SYXK 2023-0067). Consent for publication All authors agree to publish this manuscript. Availability of data and materials All data generated or analyzed during this study were included in this published article (and its additional files). Author contributions CL designed and carried out the experiments. LY carried out the characterization of materials. BZ performed cell extraction and culture in vitro. JL touched up the picture. BC analyzed the radiographic and histological data. WN interpreted the experimental data. GZ provided financial support and examined manuscripts. Competing interests The authors declare no competing financial interest. Funding This work was supported by the project funded by China Postdoctoral Science Foundation (2023M731042) and Knowledge Innovation Project in Wuhan, Hubei Province, China (2023020201020472). References Pan W, Liu C, Li YH, Yang YH, Li WL, Feng C, Li LJ. Ultrathin tellurium nanosheets for simultaneous cancer thermo-chemotherapy. Bioact Mater. 2022; 13: 96-104. Li CQ, Hou XL, Jiang DX, Zhang B, Ma MW, Xie XT, Zhao YD, Liu TC, Liu B. Binary Pt/Te nanoheterostructures with high photothermal conversion efficiency and anti-inflammatory action for enhanced photothermal therapy of 4T1 breast tumors guided by photoacoustic imaging. ACS Sustainable Chem Eng . 2022; 10: 16598-610. Huang XH, Pan JM, Xu FN, Shao BF, Wang Y, Guo X, Zhou SB. Bacteria-based cancer immunotherapy. Adv Sci. 2021; 8: 2003572. Fan JX, Niu MT, Qin YT, Sun YX, Zhang XZ. Progress of engineered bacteria for tumor therapy. Adv Drug Deliver Rev. 2022; 185: 114296. Chen QW, Liu XH, Fan JX, Peng SY, Wang JW, Wang XN, Zhang C, Liu CJ, Zhang XZ. Self-mineralized photothermal bacteria hybridizing with mitochondria-targeted metal-organic frameworks for augmenting photothermal tumor therapy. Adv Mater. 2020; 30: 1909806. Tian Lj, Min Y, Li WW, Chen JJ, Zhou NQ, Zhu TT, Li DB, Ma JY, An PF, Zheng LR, Huang H, Liu YZ, Yu HQ. Substrate metabolism-driven assembly of high-quality CdS x Se 1-x quantum dots in escherichia coli: molecular mechanisms and bioimaging application. ACS Nano 2019; 13: 5841-51. Beatriz GG, Mario CR, Ma TPC, Jörg B, María MB, Yolanda M. Combined single cell and single particle ICP-TQ-MS analysis to quantitatively evaluate the uptake and biotransformation of tellurium nanoparticles in bacteria. Anal Chim Acta 2020; 1128: 116-28. Guo YX, Chen Y, Liu XQ, Min JJ, Tan WZ, Zheng JH. Targeted cancer immunotherapy with genetically engineered oncolytic salmonella typhimurium. Cancer Lett 2020; 469: 102-10. Luzuriaga MA, Herbert FC, Brohlin OR, Gadhvi J, Howlett T, Shahrivarkevishahi A, Wijesundara YH, Venkitapathi S, Veera K, Ehrman R, Benjamin CE, Popal S, Burton MD, Ingersoll MA, Nisco NJD, Gassensmith JJ. Metal-organic framework encapsulated whole-cell vaccines enhance humoral immunity against bacterial infection. ACS Nano 2021; 15: 17426-438. Cao ZP, Cheng SS, Wang XY, Pang Y, Liu JY. Camouflaging bacteria by wrapping with cell membranes. Nat Commun. 2019; 10: 3452. Li CQ, Ma MW, Zhang B, Chen W, Yin ZY, Xie XT, Hou XL, Zhao YD, Liu B. A Self-assembled nanoplatform based on Ag 2 S quantum dots and tellurium nanorods for combined chemo-photothermal therapy guided by H 2 O 2 -activated near-infrared-II fluorescence imaging. Acta Biomater. 2022; 140: 547-60. Oved JH, Barrett DM, Teachey DT. Cellular therapy: immune-related complications. Immunol Rev. 2019; 290: 114-26. Rezvani K. Adoptive cell therapy using engineered natural killer cells. Bone Marrow Transpl. 2019; 54: 785-88. Wang C, Wang YL, Zhang LL, Miron RJ, Liang JF, Shi MS, Mo WT, Zheng SH, Zhao YB, Zhang YF. Pretreated macrophage-membrane-coated gold nanocages for precise drug delivery for treatment of bacterial infections. Adv Mater. 2018; 30: 1804023. Oved JH, Barrett DM, Teachey DT. Cellular therapy: immune-related complications. Immunol Rev. 2019; 290: 114-26. Xiong LH, Cui, R.; Zhang ZL, Cui R, Shi YB, Pang DW. Harnessing intracellular biochemical pathways for in vitro synthesis of designer tellurium nanorods. Small 2015; 11: 5416-22. Peng J.; Pan Y, Yu Z, Wu JC, Zhou Y, Guo YQ, Wu XJ, Wu CZ, Xie Y. Two-dimensional tellurium nanosheets exhibiting an anomalous switchable photoresponse with thickness dependence. Angew Chem Int Ed. 2018; 57: 13533-537. Turner R, Borghese R, Zannoni D. Microbial processing of tellurium as a tool in biotechnology. Biotechnol Adv. 2012; 30: 954-63. Li CQ, Zhao DH, Hou XL, Zhang B, Song LB, Jin RM, Zhao YD, Liu B. In situ synthesis of multifunctional tellurium nanorods stabilized by polypeptide-engineered for photothermal-sonodynamic combination therapy of tumors. Chem Eng J . 2021; 417: 127989. Sweeney E, Cano-Mejia J, Fernandes R. Photothermal therapy generates a thermal window of immunogenic cell death in neuroblastoma. Small 2018; 14: 1800678. Cheng L, Wang C, Feng LZ, Yang K, Liu Z. Functional nanomaterials for phototherapies of cancer. Chem Rev. 2014; 114: 10869-939. Zeng J, Goldfeld D, Xia YN. A Plasmon-assisted optofluidic (PAOF) system for measuring the photothermal conversion efficiencies of gold nanostructures and controlling an electrical switch. Angew Chem Int Ed. 2013; 52: 4169-73. Li SS Gu K, Wang H, Xu BL, Li HW, Shi XH, Huang ZJ, Liu HY. Degradable holey palladium nanosheets with highly active 1D nanoholes for synergetic phototherapy of hypoxic tumors. J Am Chem Soc . 2020; 142: 5649-56. Guo Q, Li XW, Zhou WX, Chu YC, Chen QJ, Zhang YW, Li C, Chen HY, Liu PX, Zhao ZH. Wang Y, Zhou Z, Luo YF, Li CF, You HY, Song HL, Su BY, Zhang TY, Sun T, Jiang Chen. Sequentially triggered bacterial outer membrane vesicles for macrophage metabolism modulation and tumor metastasis suppression. ACS Nano 2021; 15: 13826-38. Yue WW, Chen L, Yu LD, Zhou BG, Yin HH, Ren WW, Liu C, Guo LH, Zhang YF, Sun LP, Zhang K, Xu HX, Chen Y. Checkpoint blockade and nanosonosensitizer-augmented noninvasive sonodynamic therapy combination reduces tumor growth and metastases in mice. Nat Commun. 2019; 10: 2025. Ba L, Döring M, Jamier V, Jacob C. Tellurium: An element with great biological potency and potential. Org. Biomol Chem. 2010; 8: 4203-16. Sylvestre M, Crane A, Pun S. Progress on modulating tumor-associated macrophages with biomaterials. Adv Mater. 2020; 32: 1902007. Scheme Scheme 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files SupportingInformation.doc Scheme1.tif Scheme 1. (A) Schematic illustration of the preparation of RS-Te. (B) Schematic illustration of a therapeutic strategy of RS-Te-triggered photothermal immunotherapy of tumor. Cite Share Download PDF Status: Published Journal Publication published 08 Oct, 2024 Read the published version in Journal of Nanobiotechnology → Version 1 posted Editorial decision: Revision requested 02 Jun, 2024 Reviews received at journal 17 Apr, 2024 Reviewers agreed at journal 04 Apr, 2024 Reviewers invited by journal 02 Apr, 2024 Editor assigned by journal 18 Mar, 2024 Submission checks completed at journal 16 Mar, 2024 First submitted to journal 14 Mar, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4097182","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":280941950,"identity":"5aa2f643-2671-4eaf-8bd5-d2e96f7f9b6f","order_by":0,"name":"Chaoqing Li","email":"","orcid":"","institution":"Hubei University of Chinese Medicine","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Chaoqing","middleName":"","lastName":"Li","suffix":""},{"id":280941953,"identity":"d07fce30-dd92-45b8-968b-3107db7d9b22","order_by":1,"name":"Luyao Yang","email":"","orcid":"","institution":"Hubei University of Chinese Medicine","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Luyao","middleName":"","lastName":"Yang","suffix":""},{"id":280941954,"identity":"bf0b580d-6210-45e6-a7c1-43ec5d534e64","order_by":2,"name":"Bin Zhang","email":"","orcid":"","institution":"Huazhong University of Science and Technology","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Bin","middleName":"","lastName":"Zhang","suffix":""},{"id":280941955,"identity":"e37c3972-a72b-4455-a21f-8c739f5597f2","order_by":3,"name":"Jiahao Li","email":"","orcid":"","institution":"Hubei University of Chinese Medicine","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Jiahao","middleName":"","lastName":"Li","suffix":""},{"id":280941956,"identity":"f6daac41-6f00-4376-8d22-812ac61797d5","order_by":4,"name":"Bingjie Cai","email":"","orcid":"","institution":"Renmin Hospital of Wuhan University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Bingjie","middleName":"","lastName":"Cai","suffix":""},{"id":280941957,"identity":"58ecfee2-308d-4edc-94a4-8a8c91998154","order_by":5,"name":"Wei Ni","email":"","orcid":"","institution":"Hubei Provincial Hospital of Traditional Chinese Medicine","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Wei","middleName":"","lastName":"Ni","suffix":""},{"id":280941958,"identity":"be96499e-fc58-4f0f-ac91-ba0bbb318ef3","order_by":6,"name":"Gunjun Zhang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA40lEQVRIiWNgGAWjYDACCTDJJmcAYTAwNhCrxdhAgpk0LQyJG4jWIj+7+dnDL7/40rdL9x/8dIPBRnbDAeZnD/BpYZxzzNxYto8td+ecw8zSOQxpxhsOsJkb4NPCLJFgJi3Zw5a74UYyG3MOw+HEDQd42CTwaWGTSP8G0pJuANHyn7AWHokcM8kPP9gSoFoOENYiIZFTJs3YwGa44c5hY+kcg2TjmYfZzPBqkZ+Rvk3yx59j8ga3Gx9+zqmwk+073vwMrxYQYOZtOwZlgoKKmZB6IGD88aeGCGWjYBSMglEwYgEA7f9Gu8iU3AUAAAAASUVORK5CYII=","orcid":"","institution":"Hubei University of Chinese Medicine","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Gunjun","middleName":"","lastName":"Zhang","suffix":""}],"badges":[],"createdAt":"2024-03-14 04:29:36","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4097182/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4097182/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12951-024-02853-2","type":"published","date":"2024-10-08T15:57:06+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":53178086,"identity":"a5476457-61d3-4343-97ab-6f944b2f3d98","added_by":"auto","created_at":"2024-03-21 15:01:48","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":5249639,"visible":true,"origin":"","legend":"\u003cp\u003eThe preparation and characterization of RS-Te. (A) TEM image of S-Te. (B) TEM image and (C) magnified TEM image of RS-Te. (D) Dark-field image and the corresponding elemental mapping (Scale bar: 1 µm). (E) Bright field and fluorescence images of RS-Te after Te-containing Sal ingested by RAW264.7 cells (Scale bar: 50 µm). (F) XDR patterns of RS-Te. (G) Te 3d XPS spectrum of RS-Te. (H) SDS-PAGE protein patterns of biomarker (I), RAW264.7 cells (II), RS-Te (III), and S-Te (IV).\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-4097182/v1/ac0ee7b30e5baf7fcbadae48.png"},{"id":53178085,"identity":"0330675d-5ccf-4bbb-b3f2-cc848d265209","added_by":"auto","created_at":"2024-03-21 15:01:48","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":847519,"visible":true,"origin":"","legend":"\u003cp\u003eThe photothermal properties of RS-Te. (A) The UV-vis-NIR spectrum of different concentrations of Te from Sal. (B) The infrared thermal images of different concentrations of S-Te at various times under NIR laser irradiation (808 nm, 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e). (C) The temperature change curves of different concentrations of S-Te at NIR laser irradiation (1.5 W/cm\u003csup\u003e2\u003c/sup\u003e). (D) The temperature changes curves of S-Te (40 µg/mL) under different laser power densities for 10 min. (E) The photothermal hearing curves of water, dead Sal, S-Te, and TeNPs under different NIR laser irradiation times (Te concentration: 40 µg/mL). (F) The photothermal hearing curves of S-Te and RS-Te under different NIR laser times (Te concentration: 40 µg/mL). (G) Temperature changes of RS-Te for 5 laser on/off cycles (Te concentration: 40 µg/mL). (H) Temperature curves of RS-Te under laser irradiation (808 nm, 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e, Te concentration: 40 µg/mL) to reach a steady temperature and then to cool down by turning the laser off. (I) Linear time data versus negative natural logarithm of driving force temperature obtained from the cooling period of (H).\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-4097182/v1/af6b2c2ba8d12302fa470a0c.png"},{"id":53178091,"identity":"527896fe-3863-4868-ac00-e24a64a04d2d","added_by":"auto","created_at":"2024-03-21 15:01:49","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":342845,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eIn vitro\u003c/em\u003e immune stimulation effects induced by RS-Te-triggered photothermal therapy. (A) M1/M2 ratio in all macrophages with different treatments (\u003cem\u003en\u003c/em\u003e=5). (B) Proportion of M1 macrophages in all M2 macrophages with different treatments (\u003cem\u003en\u003c/em\u003e=5). (C) Quantification by mean fluorescence intensity M1/M2 ratio under various treatments. FCM analyses of percentages of (D) CD80\u003csup\u003e+\u003c/sup\u003e CD86\u003csup\u003e+\u003c/sup\u003e DCs and (E) MHC-II\u003csup\u003e+\u003c/sup\u003e DCs after BMDCs incubation with PBS, TeNPs, dead Sal, S-Te, and RS-Te for 12 h (\u003cem\u003en\u003c/em\u003e=4). FCM analyses of percentages of (F) CD80\u003csup\u003e+\u003c/sup\u003e CD86\u003csup\u003e+\u003c/sup\u003e DCs and (G) MHC-II\u003csup\u003e+\u003c/sup\u003e DCs after BMDCs incubated with 4T1 cells that had been incubated with TeNPs, S-Te, and RS-Te with or without NIR irradiation (808 nm, 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e, 5 min, Te concentration: 20 µg/mL) (\u003cem\u003en\u003c/em\u003e=4). (H) Established transwell models, the upper chamber treatment with PBS, LPS, RS-Te, or RS-Te plus laser, and FCM analyses CD86, MHC-II, TNF-α, and IL-6 in the bottom chamber. (ns: no significance, * \u003cem\u003eP\u0026lt;\u003c/em\u003e0.05, ** \u003cem\u003eP\u0026lt;\u003c/em\u003e0.01, *** \u003cem\u003eP\u0026lt;\u003c/em\u003e0.001).\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-4097182/v1/33e82ec42681c49358f8c1af.png"},{"id":53178083,"identity":"63d38e57-9e5c-4206-9fe3-6ab3a6be4264","added_by":"auto","created_at":"2024-03-21 15:01:48","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":122074,"visible":true,"origin":"","legend":"\u003cp\u003eFCM analyses of population of (A) CD80\u003csup\u003e+\u003c/sup\u003e CD86\u003csup\u003e+\u003c/sup\u003e DCs and (B) MHC-II\u003csup\u003e+\u003c/sup\u003e DCs in mice inguinal lymph nodes at 24 h after subcutaneous injection of PBS, S-Te, or RS-Te (\u003cem\u003en\u003c/em\u003e=4). (C) Live (green) and dead (red) cell staining images of macrophages after treatment with macrophage supernatant that incubated with PBS, RS, RS-Te, and LPS (Scale bar: 100 µm). (D) Quantization of 4T1 cell viability after treatment with different macrophage supernatants (\u003cem\u003en\u003c/em\u003e=3). (E) Viabilitiy of 4T1 cells after incubation with dead Sal, S-Te, RS-Te, and TeNPs with or without NIR laser irradiation (Te concentration: 20 µg/mL) (n=3) (* \u003cem\u003eP\u0026lt;\u003c/em\u003e0.05, ** \u003cem\u003eP\u0026lt;\u003c/em\u003e0.01, *** \u003cem\u003eP\u0026lt;\u003c/em\u003e0.001).\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-4097182/v1/2deecc05ab1883a72d5b9069.png"},{"id":53178092,"identity":"77f5548b-0dca-4997-9372-120060a4f535","added_by":"auto","created_at":"2024-03-21 15:01:49","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1345672,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eIn vivo\u003c/em\u003e targeting and biodistribution of RS-Te. (A) Fluorescence imaging of RS-Te-treated mice at different times by IVIS Lumina III system. (B) Semi-quantitative analysis at tumor regions (\u003cem\u003en\u003c/em\u003e=3) of 4T1 tumor-bearing mice at a series of time points. (C) \u003cem\u003eIn vivo\u003c/em\u003e distribution monitored by Te element at 6, 12, 24, 48, 72, and 96 h after intravenous injection of RS-Te (\u003cem\u003en\u003c/em\u003e=3). (D) Infrared thermal imaging of mice 24 h after intravenous injection of RS-Te under NIR laser irradiation (808 nm, 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e). (E) Temperature increase in tumor site (\u003cem\u003en\u003c/em\u003e=3) of 4T1 tumor-bearing mice with NIR irradiation.\u003c/p\u003e","description":"","filename":"Figure5.png","url":"https://assets-eu.researchsquare.com/files/rs-4097182/v1/0ca0f55ff8e324a12231e681.png"},{"id":53178087,"identity":"4458c6ff-21f3-4d99-8b7b-d9175c15f0dc","added_by":"auto","created_at":"2024-03-21 15:01:48","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":297660,"visible":true,"origin":"","legend":"\u003cp\u003e(A) Schematic diagram of mouse handling and blood sample collection. Blood biochemistry examination of (B) ALT, (C) AST, (D) BUN, (E) CRE, and (F) CRP in 4T1 tumor-bearing mice at the indicated time points (\u003cem\u003en\u003c/em\u003e=4).\u003c/p\u003e","description":"","filename":"Figure6.png","url":"https://assets-eu.researchsquare.com/files/rs-4097182/v1/8dcaacbd36b53d75235639ef.png"},{"id":53178090,"identity":"f029b712-15be-4c04-acd3-ef6ee67cb0ce","added_by":"auto","created_at":"2024-03-21 15:01:49","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":3088154,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eIn vivo\u003c/em\u003e antitumor effects and immune responses of RS-Te-mediated photothermal immunotherapy. (A) Tumor volume curves of 4T1 tumor-bearing mice after treatment with PBS, PBS+L, RS-Te, and RS-Te+L (\u003cem\u003en\u003c/em\u003e=4). (B) Representative photographs of 4T1 tumor-bearing mice after indicated in (A). (C) Representative photographs of excised tumors. (D) Average tumor weights of tumors at the endpoint. (E) Representative images of H\u0026amp;E, TUNEL, and Ki67 staining of tumor tissues obtained 24 h after the PTT treatment (Scale bar: 50 µm). (F) Mice weight curves of 4T1 tumor-bearing mice after indicated in (A). (G) H\u0026amp;E staining of major organs (heart, liver, spleen, lung, and kidney) collected from mice at 24 d post administration (Scale bar: 50 µm). (H) CD8\u003csup\u003e+\u003c/sup\u003e T cells, (I) CD4\u003csup\u003e+\u003c/sup\u003e T cells, (J) Treg, (K) M1 macrophages, and (L) M2 macrophages in tumor tissues of 4T1 tumor-bearing mice at 3 days after different treatment (PBS, S-Te, RS-Te, and RS-Te+L) (\u003cem\u003en\u003c/em\u003e=4). The level of (M) IFN-γ, (N) TNF-α, and (O) IL-6 in tumor tissues of 4T1 tumor-bearing mice after indicated in (H) (* \u003cem\u003eP\u0026lt;\u003c/em\u003e0.05, ** \u003cem\u003eP\u0026lt;\u003c/em\u003e0.01, *** \u003cem\u003eP\u0026lt;\u003c/em\u003e0.001).\u003c/p\u003e","description":"","filename":"Figure7.png","url":"https://assets-eu.researchsquare.com/files/rs-4097182/v1/9f8934af46a305534799e46d.png"},{"id":66597084,"identity":"cc876aff-d485-41a8-abca-0b3b0bc7c4cc","added_by":"auto","created_at":"2024-10-14 16:06:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":13183246,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4097182/v1/56ccea16-90fd-4f27-93cf-9825e0237484.pdf"},{"id":53178486,"identity":"88857d3a-ce02-4324-8ca3-18ff741801d7","added_by":"auto","created_at":"2024-03-21 15:09:49","extension":"doc","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":9212928,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformation.doc","url":"https://assets-eu.researchsquare.com/files/rs-4097182/v1/26c6648c2edd3d7e9711f92a.doc"},{"id":53178089,"identity":"23bb080c-0dd5-4cb5-b4a5-9f45e1d26808","added_by":"auto","created_at":"2024-03-21 15:01:48","extension":"tif","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":2396924,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme 1.\u003c/strong\u003e (A) Schematic illustration of the preparation of RS-Te. (B) Schematic illustration of a therapeutic strategy of RS-Te-triggered photothermal immunotherapy of tumor.\u003c/p\u003e","description":"","filename":"Scheme1.tif","url":"https://assets-eu.researchsquare.com/files/rs-4097182/v1/f41f16434bca18f7ad657f9a.tif"}],"financialInterests":"No competing interests reported.","formattedTitle":"Double-camouflaged tellurium nanoparticles for enhanced photothermal immunotherapy of tumor","fulltext":[{"header":"Introduction","content":"\u003cp\u003eTellurium nanoparticles (TeNPs) have been used in the photothermal therapy of tumors due to its excellent photothermal conversion properties [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. However, TeNPs still face many problems in biomedical applications, including low tumor aggregation, high systemic clearance, and unsatisfactory biocompatibility. How to safely and efficiently deliver therapeutic nanomaterials to the tumor sites to improve therapeutic outcomes remains a challenge. With more understanding of the bacteria in tumor tissues, bacteria become a promising drug carrier. One of the advantages is that the bacteria can preferentially colonize in the tumor tissues due to the chaotic vasculature, immunosuppression, hypoxia, and eutrophication of solid tumors [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Subsequently, \u003cem\u003ein situ\u003c/em\u003e synthesis of functional nanoparticles by biomineralization and bioreduction using bacteria as bioreactors and vehicles has been vigorously developed, because of bacteria facile cultivation, rapid proliferation, and high bioactivity. For example, Zhang et al. utilized \u003cem\u003eEscherichia coli\u003c/em\u003e MG1655 and \u003cem\u003eShewanella oneidensis\u003c/em\u003e MR-1 as bioreactors to synthesize gold and palladium nanoparticles on their surface and achieve tumor-targeting augmenting PTT and photothermal-controlled cytokine therapy [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. However, surface modifications by bacteria may allow drug molecules to leak prematurely, increasing unknown risks. With the assistance of bioactive molecules, bacteria could convert absorbed inorganic ions into nanoparticles without affecting their surface characteristics [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. It has been reported that tellurium nanoparticles (TeNPs) could be synthesized in a variety of bacteria [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Therefore, the synthesis of Te within bacteria was expected to be used in highly effective therapy of tumors.\u003c/p\u003e \u003cp\u003eThe inherent immunogenicity of bacteria may cause strong cytokine storms and fatal side effects during circulation in the body, which makes researchers more cautious about using bacteria-mediated therapies [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The surface of \u003cem\u003eE.coli\u003c/em\u003e strain CFT073 was biomimetically mineralized with a metal-organic framework (MOF) by Gassensmith's group [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. The encapsulation process prevented the premature exposure and destruction of bacterial surface antigens. Liu's group reported a camouflaged strategy to generate stealth bacteria by simply extruding erythrocyte membranes with bacteria, which minimizes the inflammatory reaction and side effects [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Cancer cell membranes have also been adopted to improve the performance of nanoparticle therapeutics in our previous work [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. It is worth noting that the extraction of cell membranes could more or less destroy the function of membranes. Compared to the cell membrane fragments, holistic cells have exquisite sensitivity and specificity, allowing them to sense diverse signals, move to specific sites in the body, and execute complex response behaviors [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Macrophages are the major tumor-infiltrating immune cell population with a critical role in regulating tumor progression, M1 macrophages secrete immunogenic cytokines, such as IL-12 and TNF-α, improve the immune response inhibiting effects on tumor growth [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Therefore, blocking bacteria with macrophages may be a very promising strategy for reducing bacteria-induced adverse reactions.\u003c/p\u003e \u003cp\u003eHerein, we present the development of a novel macrophage-mediated double-camouflaged delivery system (RS-Te) for enhanced photothermal immunotherapy in cancer treatment (Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). TeNPs are synthesized within attenuated \u003cem\u003eSalmonella\u003c/em\u003e (Sal, VNP 20009) by biomineralization (S-Te), and the S-Te are uptaked subsequently by macrophages. The macrophages are polarized into M1 macrophages under the action of bacteria, which possess both immunotherapeutic and tumor-homing properties. Biomineralization-induced inhibition of bacterial proliferation enhances safety \u003cem\u003ein vivo\u003c/em\u003e while preserving bacterial antigens. Our results demonstrate efficient accumulation and retention of RS-Te in tumors. Compared to laser-free irradiation, NIR laser irradiation induces a more potent therapeutic immune response by promoting dendritic cell (DC) maturation and enhancing cytotoxic T cell priming. Moreover, RS-Te reprograms tumor-associated macrophages (TAMs) to remodel the immunosuppressive tumor microenvironment by increasing the M1/M2 ratio. These immune responses optimize photothermal therapy efficacy, leading to eradication of malignant tumors and suppression of tumor metastasis. This bionic double-camouflage strategy provides innovative insights for achieving more efficient and safe drug delivery in synergistic tumor therapy.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Experimental","content":"\u003cp\u003eMaterials\u003c/p\u003e\n\u003cp\u003eNa\u003csub\u003e2\u003c/sub\u003eTeO\u003csub\u003e3\u003c/sub\u003e, Cy5.5, calcein-AM, and propidium iodide (PI) were obtained from Aladdin (Shanghai, China). Lysozyme, DAPI, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI), lipopolysaccharide (LPS), cell counting kit-8 (CCK-8), and BCA protein assay kit were purchased from Beyotime Biotechnology (Shanghai, China). Dulbecco's Modified Eagle's Medium (DMEM), and PBS were obtained from HyClone (Logan, Utah, USA). Penicillin-streptomycin, FBS, and trypsin were purchased from Gibco Life Technologies (Grand Island, NY, USA). PE-conjugated anti-mouse CD86, PE-conjugated anti-mouse CD80, PE-conjugated anti-mouse CD206, FITC-conjugated anti-mouse CD11b, APC-conjugated anti-mouse CD3, PE-conjugated anti-mouse CD8, FITC-conjugated anti-mouse CD4, PE-conjugated anti-mouse MHC-II anti-mouse MHC-II antibody, and purified anti-catalase antibody were purchased BioLegend (USA). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) loading buffer and tumor-infiltrating tissue lymphocyte separation kit were purchased from Beijing Solarbio Science \u0026amp; Technology (China). BALB/c female mice were purchased from Beijing Vital Laboratory Animal Technology Co., Ltd. (Beijing, China).\u003c/p\u003e\n\u003cp\u003eCharacterizations\u003c/p\u003e\n\u003cp\u003eThe morphologies of samples were checked by a transmission electron microscope (TEM, HT7700, Hitachi, Japan). TEM-assisted element mapping imaging was conducted on a Talos F20× atomic resolution analytical microscope (PEI, Netherlands). X-ray diffractometry (XRD) spectrum was conducted by a PANalytical B.V., Netherlands. The sizes and zeta potentials of probes were obtained on a ZS90 Zeta Sizer (Malvern, UK). The fluorescence imaging of cells was obtained by a confocal laser scanning microscope (CLSM, FV3000, Olympus, Japan). The flow cytometry (FCM) was conducted by an FC500 flow cytometry (Beckman Coulter, USA). The \u003cem\u003ein vivo\u003c/em\u003e and \u003cem\u003ein vitro\u003c/em\u003e fluorescence imaging were realized by a small animal fluorescence imaging system (IVIS Spectrum, PerkinElmer). The light sources of photothermal experiments were used by an MDL-III-808-2.5 W laser (Changchun New Industries Optoelectronics Tech. Co. Ltd., China). Infrared thermal images were recorded by an EasIR-9 thermal imager (Wuhan Guide Infrared Co., Ltd., China).\u003c/p\u003e\n\u003cp\u003ePreparation of RS-Te\u003c/p\u003e\n\u003cp\u003eVNP20009 Sal was cultured in Luria-Bertani (LB) broth (10 g/L tryptone, 5 g/L yeast extract, and 10 g/L NaCl) at 37°C. For S-Te synthesis, Na\u003csub\u003e2\u003c/sub\u003eTeO\u003csub\u003e3\u003c/sub\u003e (0.8 mM) was added into 30 mL of bacterial suspension (2×10\u003csup\u003e9\u003c/sup\u003e CFU/mL) and the mixture was incubated in a shaking incubator (37°C, 220 rpm) for 4 h. The black S-Te was obtained by centrifugation at 5000 rpm for 5 min, then washed three times and stored at 4°C. S-Te (1×10\u003csup\u003e5\u003c/sup\u003e CFU/mL) was incubated with RAW264.7 cells in 6-well plate for 2 h at 37°C in an incubator with 5% CO\u003csub\u003e2\u003c/sub\u003e to obtain RS-Te. The RS-Te were washed three times and digested, resuspended in PBS, and stored at 4°C.\u003c/p\u003e\n\u003cp\u003ePreparation dead Sal\u003c/p\u003e\n\u003cp\u003eTo obtain dead Sal, cultured Sal was collected, washed, resuspended in PBS, and inactivated by pasteurization for 30 min at 70°C.\u003c/p\u003e\n\u003cp\u003ePreparation of TeNPs\u003c/p\u003e\n\u003cp\u003eThe prepared S-Te was treated with lysozyme and ultrasonic homogenizer (Scientz, Ningbo, China). The supernatants were centrifugated three times at 8000 rpm for 5 min. TeNRs were resuspended in PBS and stored at 4°C.\u003c/p\u003e\n\u003cp\u003ePhotothermal property study\u003c/p\u003e\n\u003cp\u003eAbsorption spectra of various concentrations of RS-Te (Te concentration: 10, 20, 30, and 40 µg/mL) in PBS were acquired by a UV-2550 visible Spectrophotometer (Shimadzu, Japan). RS-Te suspensions (300 µL) of different concentrations (Te concentration: 10, 20, and 40 µg/mL) were irradiated by 808 nm laser (1.5 W/cm\u003csup\u003e2\u003c/sup\u003e, 10 min), and the temperature of suspensions was recorded by an infrared thermal camera. RS-Te suspensions (40 µg/mL) was irradiated by 808 nm laser at different power densities (0.75, 1.0, and 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e) for 10 min, and the temperatures and infrared thermal images were recorded. The photothermal performances of S-Te, TeNPs, and dead Sal at Te concentration of 40 µg/mL were studied with irradiation of 808 nm laser at 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e for 10 min. Photothermal stability of RS-Te was studied under the above conditions over five cycles of alternating heating and cooling. The photothermal conversion efficiency (\u003cem\u003eη\u003c/em\u003e) of mPT was calculated by the following formula:\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003ewhere \u003cem\u003ehs\u003c/em\u003e = \u003cem\u003emc\u003c/em\u003e/\u003cem\u003eτ\u003c/em\u003e, \u003cem\u003eQ\u003c/em\u003e\u003csub\u003eDis\u003c/sub\u003e = \u003cem\u003ehs\u003c/em\u003e × (\u003cem\u003eT\u003c/em\u003e\u003csub\u003emax of water\u003c/sub\u003e − \u003cem\u003eT\u003c/em\u003e\u003csub\u003esurr\u003c/sub\u003e), \u003cem\u003em\u003c/em\u003e was the mass of solution (g), \u003cem\u003ec\u003c/em\u003e was specific heat of water (J/g•°C), \u003cem\u003eI\u003c/em\u003e was laser power (W) and \u003cem\u003eA\u003c/em\u003e\u003csub\u003e808\u003c/sub\u003e was absorption at 808 nm.\u003c/p\u003e\n\u003cp\u003eCell culture\u003c/p\u003e\n\u003cp\u003eMurine breast cancer 4T1 cells and murine RAW264.7 macrophages were purchased from Type Culture Collection of the Chinese Academy of Sciences (Shanghai, China). 4T1 cells and RAW264.7 macrophage cells were cultured in DMEM medium supplemented with 10% FBS, penicillin (100 U/mL), and streptomycin (100 µg/mL) at 37°C in a 5% CO\u003csub\u003e2\u003c/sub\u003e incubator, respectively. M2 macrophages were obtained by stimulating RAW264.7 cells with IL-4 (20 ng/mL) for 24 h. Murine bone marrow-derived DCs (BMDCs) were obtained by culturing bone marrow cells in RPMI 1640 complete medium with addition of GM-CSF (10 ng/mL) and IL-4 (10 ng/mL) for 7 days.\u003c/p\u003e\n\u003cp\u003eCellular uptake assay\u003c/p\u003e\n\u003cp\u003eRAW264.7 cells were incubated with GFP-marked S-Te at the concentration of 20 µg/mL Te for 2 h to obtain RS-Te. Then, the cells were rinsed with PBS three times, fixed with 4% paraformaldehyde solution for 20 min, and stained with DAPI (1 µg/mL) for 5 min. The cells were observed by FV3000 CLSM. Preparation of RS-Te was further studied via TEM. The RS-Te were fixed with 2.5% glutaraldehyde solution, and collected for TEM sample preparation. The cells were observed by TEM.\u003c/p\u003e\n\u003cp\u003eWestern blot\u003c/p\u003e\n\u003cp\u003eBacteria and cells were harvested and disrupted using sonication and the supernatants were collected. All protein samples were subjected to 12% SDS-PAGE and transferred to polyvinylidene fluoride membranes.\u003c/p\u003e\n\u003cp\u003eCytotoxicity of RS-Te\u003c/p\u003e\n\u003cp\u003eTo evaluate the cytotoxicity of RS-Te \u003cem\u003ein vitro\u003c/em\u003e, 4T1 cells were treated with different conditions, including PBS, dead Sal, S-Te, RS-Te, and TeNPs with or without laser for 12 or 24 h. Then, the cell viability was measured by CCK-8 assay.\u003c/p\u003e\n\u003cp\u003eIn vitro macrophage analysis\u003c/p\u003e\n\u003cp\u003eRAW264.7 cells were seeds into 24-well culture plates at a density of 1×10\u003csup\u003e5\u003c/sup\u003e per well and incubated overnight at 37°C, followed by the treatment of IL-4 for 48 h to induce the M2 polarization. Then, M2 macrophages were treated with PBS, TeNPs, S-Te, RS-Te, dead Sal, and LPS (100 ng/mL) at the same concentration (Te concentration: 20 µg/mL). After incubation for 12 h, cells were harvested, and the expression of M1 macrophage-related marker CD86, MHC-II, and inflammation-related cytokines (TNF-α, IL-12, TGF-β, and IL-10) were analyzed.\u003c/p\u003e\n\u003cp\u003eIn vitro and in vivo DCs maturation\u003c/p\u003e\n\u003cp\u003e4T1 cells were treated with dead Sal, TeNRs, S-Te, and RS-Te at the same concentrations (Te concentration: 20 µg/mL) for 2 h. Then, the cells were treated with or without laser irradiation (808 nm, 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e, 5 min). The culture supernatants and debris of 4T1 cells in different groups were added into immature BMDCs, respectively. After incubation for another 24 h, the cells were collected, and stained with fluorescence-labeled anti-CD11b, anti-CD80, anti-CD86, anti-CD206, and anti-MHC-II antibodies. The stained cells were analyzed by FCM.\u003c/p\u003e\n\u003cp\u003eTranswell model was established to analyze the DCs maturation \u003cem\u003ein vitro\u003c/em\u003e. Murine BMDCs from marrow cavities of femurs and tibias of mice were cultivated in plates with a medium containing 20 ng/mL GM-CSF and 20 ng/mL IL-4 7 days after, BMDCs were seeded in the lower chamber of transwell plates at a density of 5×10\u003csup\u003e5\u003c/sup\u003e per well. 4T1 cells were seeded in the upper chamber of transwell plates at a density of 5×10\u003csup\u003e5\u003c/sup\u003e per well, following the treatment of PBS, LPS (100 ng/mL), RS-Te, or RS-Te plus laser (Te concentration: 20 µg/mL). After administration for 24 h, the BMDCs were collected, the TNF-α and IL-6 in supernatants were analyzed and BMDCs were suspended with PBS containing PE-conjugated anti-mouse CD80, PE-conjugated anti-mouse CD86, and PE-conjugated anti-mouse MHC-II by FCM.\u003c/p\u003e\n\u003cp\u003eFor \u003cem\u003ein vivo\u003c/em\u003e DCs stimulation experiments, female Balb/c mice were subcutaneously injected with PBS, S-Te, and RS-Te (\u003cem\u003en\u003c/em\u003e = 4, Te concentration: 20 µg/mL). At 24 h after administration, the mice were sacrificed, and cells were collected from the inguinal lymph nodes for analysis by staining with fluorescence-labeled anti-CD11b, anti-CD80, anti-CD86, anti-CD206, and anti-MHC-II antibodies.\u003c/p\u003e\n\u003cp\u003eIn vivo biosafety\u003c/p\u003e\n\u003cp\u003eThe mice (female, SPF, 5 weeks) were intravenously injected with Sal, S-Te, and RS-Te (Te concentration: 1 mg/kg), another RS-Te group was irradiated by laser, and PBS group as control. The body weight and temperature of mice were recorded every day for 24 days. Serum and anticoagulant blood were collected on days 0.5, 1, and 14 for blood biochemistry (ALT and AST for liver function, BUN and CREA for kidney function, and CRP for inflammation and infection) and blood routine examination (WBC, RBC, and PLT), respectively.\u003c/p\u003e\n\u003cp\u003eIn vivo photothermal performance and antitumor activity\u003c/p\u003e\n\u003cp\u003eWhen the tumor reached 90 mm\u003csup\u003e3\u003c/sup\u003e, 4T1 tumor-bearing Balb/c mice (5 weeks) were randomly divided into 4 groups (4 mice of each group), including: (I) PBS, intravenously injected with 200 µL of PBS; (II) PBS + L, intravenously injected with 200 µL of PBS, at 24 h post-administration, the tumors were irradiated with 808 nm laser for 10 min at power densities 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e; (III) RS-Te, intravenously injected with 200 µL of RS-Te suspension, (Te concentration: 1 mg/kg); (IV) RS-Te, intravenously injected with 200 µL of RS-Te suspension, (Te concentration: 1 mg/kg), at 24 h post-administration, the tumors were irradiated with 808 nm laser for 10 min at power densities 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e. The body weight of the mice and the length and width of the tumor were recorded every two days. The volume of tumor was monitored during the observation period as follows: \u003cem\u003eV\u003c/em\u003e = \u003cem\u003eW\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e×\u003cem\u003eL\u003c/em\u003e/2, where \u003cem\u003eW\u003c/em\u003e and \u003cem\u003eL\u003c/em\u003e were the length in minor and major axes, respectively. The mice were sacrificed on the 24th day, the tumors were harvested and weighed. The major tissues of mice were collected and stained by H\u0026amp;E.\u003c/p\u003e\n\u003cp\u003eIn vivo immune response\u003c/p\u003e\n\u003cp\u003e4T1 tumor-bearing mice (five weeks, female) were randomly divided into four groups (four mice/per group). The mice were intravenously injected with PBS, S-Te, and RS-Te, after 24 h postinjection, another group of RS-Te was treated with laser irradiation (1.5 W/cm2, 10 min). At 48 h post-administration, the mice were sacrificed, and Tumor-draining lymph nodes (DLNs) and tumors were harvested for analysis of immune responses. The tumors were cut into pieces and digested with DMEM medium containing 0.8 mg/mL collagenase I for 40 min at 37°C. The digested tumors were ground by a syringe plunger on a 40 µm cell strainer to generate single-cell suspensions. Single-cell suspensions of DLNs were directly obtained by mashing the tissues through a 40 µm cell strainer.\u003c/p\u003e\n\u003cp\u003eFor T cell analysis, the cells were stained with CD3, CD4, and CD8 antibodies. For Treg analysis, cells were stained with CD4 and Foxp3 antibodies. For M1 macrophages analysis, cells were stained with CD11b and CD86 antibodies. For M2 macrophages analysis, cells were stained with CD11b and CD206 antibodies. Then, stained cells were washed with PBS three times and measured by FCM.\u003c/p\u003e\n\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003eStatistical analysis\u003c/h2\u003e\n \u003cp\u003eStatistical analyses were conducted and the results were presented as mean ± standard deviation. 2-tailed Student's t-test or one-way analysis of variance was utilized to determine statistical significance between two or more groups, respectively. The significance of difference was indicated as (ns: no significance, * \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.05, ** \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.01, and *** \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001).\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results and discussion","content":"\u003cp\u003eFabrication and characterization of RS-Te\u003c/p\u003e\n\u003cp\u003eThe sodium tellurite (Na\u003csub\u003e2\u003c/sub\u003eTeO\u003csub\u003e3\u003c/sub\u003e) was added into the medium during the culture of Sal, and rod-like nanostructures were observed inside Sal by TEM (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eA). Meanwhile, the color of Sal suspension turned to black (Additional file 1: Fig. \u003cspan class=\"InternalRef\"\u003eS1\u003c/span\u003e), which may be attributed to the reduction of Te oxyanions via the intracellular glutathione (GSH), reduced nicotinamide dinucleotide phosphate and GSH reductase in Sal and the spontaneous decomposition of the obtained Te precursor (GSTeH) [\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e]. A large number of Sal could be found in the RAW264.7 cell by TEM after incubating the S-Te (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eB), and the TeNPs in the Sal could also be clearly observed through magnified TEM (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eC). The elements composition and distribution of RS-Te were analyzed by elemental mapping images, containing Te and elements from Sal (P, S, and N) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eD). After the macrophages and Sal with green fluorescent protein (GFP) were co-cultured, bright green fluorescence was observed in a large number of RAW264.7 cells, suggesting successful uptake of the Sal by the RAW264.7 cells (Additional file 1: Fig. S2). To further characterize the bacterial uptake behavior of macrophages, the RAW264.7 cell membrane was labeled with a red fluorescent dye (DiI), and the nucleus was located via 4',6-diamidino-2-phenylindole (DAPI, blue fluorescence). The GFP was visually observed in the RAW264.7 cells by CLSM (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eE), indicating that Sal was successfully taken up by RAW264.7 cells. The XRD pattern of Te from RS-Te matched well with the standard diffraction pattern (JCPDS No. 36-1452) of hexagonal Te, in which the diffraction peaks of Te could be indexed to (100), (101), (110), (201), and (113) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eF). The valence state of Te from RS-Te was analyzed by X-ray photoelectron spectroscopy. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eG, the characteristic peaks at binding energies of 572.9 and 583.0 eV were assigned to Te 3d\u003csub\u003e5/2\u003c/sub\u003e and Te 3d\u003csub\u003e3/2\u003c/sub\u003e of Te\u003csup\u003e0\u003c/sup\u003e, while the characteristic peaks at binding energies of 575.5 and 585.9 eV were assigned to Te 3d\u003csub\u003e5/2\u003c/sub\u003e and Te 3d\u003csub\u003e3/2\u003c/sub\u003e of tellurium oxide, which might be attributed to the easily-occurred tellurium oxide in natural environment [\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e]. Compared to the size of a single RAW264.7 cell, there was no significant change observed in the size of RS-Te (Additional file 1: Fig. S3A), and the surface charges of both the single RAW264.7 cell and RS-Te were found to be comparable (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eB). These findings suggest that RAW264.7 cells maintained their integrity after internalizing Sal-containing Te. In addition, SDS-PAGE (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003eH) analysis showed that RS-Te had similar protein bands compared with the profile of S-Te and single RAW264.7 cell, indicating that the surface proteins of the Sal were still present after the Sal were ingested by RAW264.7 cells. The result is helpful for the activation of the immune response \u003cem\u003ein vivo\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003eStudies have shown that tellurates and tellurites are toxic, and they could inhibit bacterial growth [\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e]. As demonstrated in Additional file 1: Fig. S4A, with the increase of Na\u003csub\u003e2\u003c/sub\u003eTeO\u003csub\u003e3\u003c/sub\u003e concentration, the absorption value (OD\u003csub\u003e600\u003c/sub\u003e) of Sal gradually decreased, and a concentration of 0.8 mM had a significant inhibitory effect on Sal growth. When the above samples were further diluted (1\u0026times;10\u003csup\u003e4\u003c/sup\u003e) and cultured on the solid LB plates, that the Sal multiplication ability was significantly inhibited compared with the untreated group (Additional file 1: Fig. S4B). These results showed that the mechanism of cytoplasmic synthesis of TeNPs in Sal might be related to the detoxification of tellurates and tellurites, by generating Te\u003csup\u003e0\u003c/sup\u003e and tellurium oxide with less toxicity. To balance high biomineralization efficiency and low proliferation rate, the 0.8 mM Na\u003csub\u003e2\u003c/sub\u003eTeO\u003csub\u003e3\u003c/sub\u003e was chosen for the preparation of the S-Te.\u003c/p\u003e\n\u003cp\u003ePhotothermal properties of RS-Te\u003c/p\u003e\n\u003cp\u003eRod-like TeNPs based on polypeptide-mineralization have shown to have excellent photothermal conversion and tumor ablation capabilities in our previous work [\u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e], and it was reported that PTT elicited immunogenic cell death (ICD) by inducing dying tumor cells to release damage-associated molecules [\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e]. The UV-vis-NIR absorption spectra of Te showed that Te presented a wide light absorption spectrum, which is positively correlated with the concentration of Te (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eA). To explore whether the biomineralized S-Te has acceptable photothermal properties, a thermal imager was introduced to record the temperature changes of the different concentrations of S-Te under NIR laser irradiation (808 nm, 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e). As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eB, Te concentrations in S-Te suspensions are positively correlated with temperature increases. The corresponding quantitative data are shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eC. Upon irradiation with an NIR laser, the temperature of S-Te suspension at Te concentration of 40 \u0026micro;g/mL increased by 35.8\u0026deg;C, while water only slightly increased by 4.3\u0026deg;C. Under NIR laser irradiation for 10 min, the temperature changes of S-Te (40 \u0026micro;g/mL) at different power densities (0.75, 1.0, and 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e) were measured to be 16.7, 23.4, and 33.8\u0026deg;C, respectively, suggesting a power density-dependent photothermal effect of S-Te (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eD). These obvious temperature changes provided favorable conditions for \u003cem\u003ein vivo\u003c/em\u003e applications of S-Te. In addition, S-Te exhibited a similar temperature rise as TeNPs from Sal at the same condition, while dead Sal and water showed negligible temperature changes. The results reveal the photothermal property from TeNPs rather than bacteria in photothermal heating of S-Te (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eE). It is worth noting that there was little difference between the temperature changes of the RS-Te and S-Te upon NIR laser irradiation (Te: 40 \u0026micro;g/mL, 808 nm, 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e), indicating that the double-camouflaged strategy had little effect on the photothermal properties of the delivery platform (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eF). It was found that the temperature curve was an inappreciable change after 5 repeated irradiation cycles, revealing the remarkable photothermal conversion stability of RS-Te (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eG). Moreover, the time constant (\u003cem\u003e\u0026tau;\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e) was measured to be 219.36 s, and photothermal conversion efficiency was calculated to be 33.8% (\u003cem\u003e\u0026eta;\u003c/em\u003e), which is higher than that of common photothermal nanoagents in the PTT (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eH, I), such as Au nanorods (22%), CuS nanoparticles (28.8%), and Pd nanosheets (30.9%) [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e]. Together, these results indicate the superior NIR photothermal performance and high photostability of RS-Te, implying its potential for PTT of tumors.\u003c/p\u003e\n\u003cp\u003eIn vitro immune stimulation performance induced by RS-Te-triggered PTT\u003c/p\u003e\n\u003cp\u003eAs one of the key immune cells involved in cancer immunity, macrophages are one of the most abundant circulating cells in the body [\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e]. To investigate whether biomineralized S-Te could polarize macrophages into M1 macrophage cells, FCM was introduced to analyze the ratio of M1 and M2 in macrophage samples after different treatments. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eA, an significant increase of the macrophages M1/M2 rations was found in raw macrophages incubated with S-Te, RS-Te, dead Sal, and LPS (the positive control), while the update in the TeNPs group was negligent comparing with the untreated group, which implies that the Sal played a key role in the polarization of macrophages. Furthermore, the proportional ratio increase of M1/M2 macrophages in the RS-Te group might be caused by secreting chemokines by RS-Te this chemokines induce macrophage polarization. To further investigate the effect of RS-Te on TAMs remodeling, IL-4-conditioned RAW264.7 cells (M2 macrophages) were incubated with PBS, TeNPs, RS-Te, S-Te, and LPS for 12 h (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eB). The proportion of M1/M2 was significantly increased in the S-Te, RS-Te, dead Sal, and LPS groups compared with the TeNPs and PBS groups. Correspondingly, the mean fluorescence intensity (MFI) of CD86\u003csup\u003e+\u003c/sup\u003e (M1 macrophage marker) significantly increased in S-Te, RS-Te, dead Sal, and Sal groups compared with PBS and TeNPs groups (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eC). Besides, the secretion of proinflammatory factors, such as TNF-\u0026alpha; and IL-12, markedly increased in IL-4-conditioned RAW264.7 cells (Additional file 1: Fig. S5A, B). The contents of M2 macrophage-related cytokines in the samples were also detected by FCM, such as TGF-\u0026beta; and IL-10. Moreover, their levels were found to be significantly decreased in the S-Te, RS-Te, dead Sal, and LPS groups (Additional file 1: Fig. S5C, D), suggesting an effective polarization from the M2 phenotype to the M1 phenotype.\u003c/p\u003e\n\u003cp\u003eAntigen-presenting cells (APCs) play a key role in the initiation and regulation of innate and adaptive immune responses. Once exposed to antigens, the immature DCs transform into maturation for antigen processing and presenting [\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e]. Therefore, DCs maturation induced by RS-Te was analyzed by FCM to measure the expression levels of co-stimulatory molecules (CD80, CD86, and MHC-II). Compared with the PBS group, the expression levels of CD80\u003csup\u003e+\u003c/sup\u003e CD86\u003csup\u003e+\u003c/sup\u003e in BMDCs incubated with dead Sal and S-Te increased 2.52 and 2.47 times, respectively. However, no obvious change was found when BMDCs incubated with TeNPs, indicating that it was Sal in S-Te that promoted the maturation of DCs \u003cem\u003ein vitro\u003c/em\u003e (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eD). It is worth noting that the expression levels of CD80\u003csup\u003e+\u003c/sup\u003e CD86\u003csup\u003e+\u003c/sup\u003e in the RS-Te group were 1.67 times higher than that of the S-Te group, which might be due to the fact that RS-Te enriched with more Sal and that the polarized RS-Te further matured the BMDCs by secreting related cytokines. The expression levels of MHC-II also presented a similar trend in BMDCs with different treatments (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eE). To investigate whether RS-Te-trigged PTT maturate DCs \u003cem\u003ein vitro\u003c/em\u003e, supernatants and 4T1 cell debris after various treatments were collected and incubated with BMDCs for 12 h. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eF, G, compared with the control group, supernatants and 4T1 cell debris incubated with either S-Te or RS-Te could induce higher expression of CD80\u003csup\u003e+\u003c/sup\u003e CD86\u003csup\u003e+\u003c/sup\u003e and MHC-II of BMDCs, whether plus or not. These results indicate that the bacteria and M1 macrophage could act as immune adjuvant for DC maturation induction. For all groups with laser irradiation, DC maturation could be further promoted. In particular, BMDCs in 4T1\u0026thinsp;+\u0026thinsp;RS-Te\u0026thinsp;+\u0026thinsp;Laser group exhibited the highest expression of CD80\u003csup\u003e+\u003c/sup\u003e CD86\u003csup\u003e+\u003c/sup\u003e and MHC-II among all groups, indicating that ICD induced by photothermal was another major player for DCs maturation. Moreover, the transwell models were established to simulate RS-Te-triggered PTT in TME. 4T1 cells were cultured in the upper chamber and BMDCs were cultured in the bottom chamber (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eH). Then, the upper chamber was separately treated with PBS, LPS, RS-Te, and RS-Te\u0026thinsp;+\u0026thinsp;Laser. The FCM assay results show that RS-Te, and RS-Te\u0026thinsp;+\u0026thinsp;Laser treated BMDCs significantly increased the expression of costimulatory molecules, including CD86 and MHC-II (Additional file 1: Fig. S6A, B). Correspondingly, the secretion of proinflammatory factors, such as TNF-\u0026alpha; and IL-6, also increased (Additional file 1: Fig. S6C, D). In particular, after NIR laser irradiation, the levels of TNF-\u0026alpha; and IL-6 in the RS-Te\u0026thinsp;+\u0026thinsp;Laser group were 2.18 and 2.33 times higher than that of the RS-Te group, respectively. Considering the importance of the role of MHC molecules in antigen presentation and impressive ICD induced by RS-Te, RS-Te-triggered PTT has a great advantage in synergistically enhancing tumor immunotherapy. To further explore whether RS-Te could stimulate DCs maturation \u003cem\u003ein vivo\u003c/em\u003e, the inguinal lymph nodes from healthy mice are collected after 24 h subcutaneous injection of RS-Te. The percentages of mature DCs in inguinal lymph nodes showed a significant elevation compared with the control group (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eA, B), which confirms the ability of RS-Te to stimulate DCs maturation \u003cem\u003ein vivo\u003c/em\u003e. All of the results imply that RS-Te could transform M2 macrophages into M1 macrophages, and has the potential to remodel the immunosuppressive TME and promote antitumor immune responses.\u003c/p\u003e\n\u003cp\u003eAntitumor effects and immune responses of RS-Te-mediated photothermal immunotherapy in vitro\u003c/p\u003e\n\u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eD, E, RAW264.7 remained active after incubating the S-Te. The live/dead cells were respectively stained by calcein-AM (green fluorescence) and PI (red fluorescence) to evaluate the viability of RAW264.7 cells, untead RAW264.7 cells as a control (RAW), macrophages were incubated with Sal, S-Te, and LPS as RS, RS-Te, and RL groups, respectively. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eC, no red fluorescence was observed after different treatments, confirm the specificity of RS-Te. After incubating the above supernatant with 4T1 cells, the results of the CCK-8 experiment showed that the cell viability decreased to a certain extent in RS, RS-Te, and RL groups compared with the PBS and RAW groups, suggesting RS-Te secretion had tumor cells killing effect (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eD). Follow more, RS-Te was examined \u003cem\u003ein vitro\u003c/em\u003e. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003eE, 4T1 cell viabilities decreased to 73.8% after incubation with RS-Te for 24 h, compared with the 4T1 cells incubated S-Te. The results show that RS-Te could retain its normal activity and kill cancer cells, which is consistent with the previous results (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eD, E). 4T1 cells exhibited high viabilities after incubation with TeNPs, Dead\u0026thinsp;+\u0026thinsp;Sal, Dead\u0026thinsp;+\u0026thinsp;Sal\u0026thinsp;+\u0026thinsp;laser, and S-Te, while 4T1 cell viabilities significantly decreased at TeNRs plus laser, S-Te plus laser, and RS-Te plus laser groups for 24 h (Te concentration: 30 \u0026micro;g/mL). The results indicate that it was the photothermal conversion ability of TeNPs that caused the temperature hike, led to cell death. Especially, compared with the S-Te\u0026thinsp;+\u0026thinsp;laser group, the 4T1 cell viability decreased to 8.03% after 4T1 cells were incubated with RS-Te plus laser for 24 h. These results show the prominent photothermal therapeutic efficacy of RS-Te under NIR irradiation.\u003c/p\u003e\n\u003cp\u003eIn vivo tumor targeting and biodistribution of RS-Te\u003c/p\u003e\n\u003cp\u003eTo validate the tumor-homing ability of RS-Te, subcutaneous 4T1 tumor-bearing mice models were established, and the NIR fluorescence dye Cy5.5-labeled RS-Te was employed for the real-time fluorescence monitoring of \u003cem\u003ein vivo\u003c/em\u003e biodistribution and metabolism for a long time. The corresponding results are illustrated in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eA. After intravenous injection of the RS-Te (Te concentration: 1.0 mg/kg), the fluorescence signal of the tumor site gradually increased, and reached to peak at 24 h, showing the excellent tumor retention capacity of RS-Te. The fluorescence signal quantization results of the tumor site in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eB are consistent with those observed above. Blood samples were then collected at different time points, and Te concentrations were measured to determine how the RS-Te metabolized \u003cem\u003ein vivo\u003c/em\u003e over time. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eC, less RS-Te accumulated in the heart, which avoided the risk of acute toxicity by Te [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e]. Especially, a fairly high concentration of Te was detected at the tumor site, verifying that RS-Te administered systemically could efficiently accumulate and retain in tumors. These data verified that the prepared RS-Te possessed high tumor-homing ability. Thanks to gratifying enrichment ability, the \u003cem\u003ein vivo\u003c/em\u003e photothermal properties of RS-Te were verified by NIR laser irradiation at the tumor site after 24 h intravenous injection of RS-Te and PBS. The thermal imaging data (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eD) revealed that a significant temperature increase of the tumor site could be observed after NIR laser irradiation for 10 min (808 nm, 1.5 W/cm\u003csup\u003e2\u003c/sup\u003e). The temperature changes in the tumor site are recorded (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eE), the temperature of the tumor site rose rapidly within 4 min and reached 59.3\u0026deg;C after 10 min irradiation with NIR laser, indicating RS-Te possessed excellent photothermal conversion properties \u003cem\u003ein vivo\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003eEnhanced biosafety of RS-Te\u003c/p\u003e\n\u003cp\u003eTo assess the biocompatibility and biosafety of RS-Te, the physiological and biochemical changes were monitored in healthy mice by intravenously injecting RS-Te at a Te concentration of 1.0 mg/kg. As demonstrated in Additional file 1: Fig. S7A, administration of S-Te, RS-Te, and RS-Te\u0026thinsp;+\u0026thinsp;Laser induced slight weight loss and the weight loss was gradually recovery in 14 days, while all mice receiving the Sal all died within 48 h. This is possibly due to the rapid proliferation of Sal in the body. The body temperature of the mice treated with S-Te, RS-Te, and RS-Te\u0026thinsp;+\u0026thinsp;Laser slightly dropped and back to normal within 4 h, while the Sal-treated mice showed a significant decrease in body temperature (Additional file 1: Fig. S7B). Moreover, blood biochemistry and routine examinations were carried out at 0.5, 1, and 14 days after intravenous injection. The mice in the Sal group had died after 1 day, so the data were no longer recorded (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e). Following the injection of S-Te, there was a sharp increase of liver function marker ALT and AST and kidney function marker BUN and CRE in the serum levels on the 1st day (Additional file 1: Fig. S9B-E). Also, a spike of CRP concentration was detected on the 1st day after treatment with S-Te, manifesting the occurrence of inflammation or infection (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eF). Compared to the PBS group, these markers were slightly elevated in the RS-Te group and gradually backed to normal within 14 days, this could be an indicator that the macrophage modification strategy greatly reduced the risk of bacterial infection and significantly improved the biosafety of the delivery vector. The trend of blood biochemistry and routine indexes change in RS-Te\u0026thinsp;+\u0026thinsp;Laser were similar to that of the RS-Te group, indicating that laser treatment did not cause serious body damage. Overall, the system of S-Te delivery by RS-Te significantly enhanced the safety and potential for \u003cem\u003ein vivo\u003c/em\u003e applications.\u003c/p\u003e\n\u003cp\u003eAntitumor effects and immune responses of RS-Te-mediated photothermal immunotherapy in vivo\u003c/p\u003e\n\u003cp\u003eSpurred by the prominent photothermal conversion and immune response feature of RS-Te \u003cem\u003ein vitro\u003c/em\u003e, the \u003cem\u003ein vivo\u003c/em\u003e antitumor effects of intravenously injected RS-Te upon NIR irradiation were evaluated. 4T1 tumor-bearing mice (5 weeks, female) were randomly divided into 4 groups (4 mice/per group). At 24 h post systemic administration of PBS or RS-Te via tail vein, the mice were illuminated with or without NIR laser irradiation (1.5 W/cm\u003csup\u003e2\u003c/sup\u003e, 10 min), and the 4 groups were denoted as PBS, PBS\u0026thinsp;+\u0026thinsp;Laser (PBS\u0026thinsp;+\u0026thinsp;L), RS-Te, and RS-Te\u0026thinsp;+\u0026thinsp;Laser (RS-Te\u0026thinsp;+\u0026thinsp;L) groups, respectively. Tumor growth was barely inhibited in the PBS and PBS\u0026thinsp;+\u0026thinsp;L groups (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eA). Although tumor growth was slower in the RS-Te group compared with the PBS and PBS\u0026thinsp;+\u0026thinsp;L groups, the tumor volume reached to 659.87 cm\u003csup\u003e3\u003c/sup\u003e during the observation period. On the contrary, after NIR laser treatment, tumors in the RS-Te\u0026thinsp;+\u0026thinsp;L group were almost eliminated. The tumor growth status is shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eB. On day 24, all mice were euthanized, and the tumors were collected and photographed (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eC). The mean tumor weight in each group was calculated (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eD). The tumor volume and weight were comparable with monitoring data. Moreover, the H\u0026amp;E, Ki67, and TUNEL staining showed that the RS-Te\u0026thinsp;+\u0026thinsp;L group initialized the most potent apoptosis effect and the lowest proliferation of tumor cells (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eE). Those results indicated that the RS-Te had excellent PTT ability. The other groups showed a slight body weight loss within two days of different treatments except for the PBS group. This may be explained by mice's excessive stress response, and the body weight of mice gradually recovered and gained a slight amount of weight (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eF). At the end of treatment, the major organs of mice were sectioned and analyzed (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eG). The tissue structure of the PBS, RS-Te, and RS-Te\u0026thinsp;+\u0026thinsp;L groups was similar to that of the PBS group, and no obvious structural damage was observed, which confirms the safety of the RS-Te. Since tumor nodules were found in the PBS group but not in the RS-Te\u0026thinsp;+\u0026thinsp;L group, we further carred out H\u0026amp;E staining for the lungs tissue of each group (Additional file 1: Fig. S8). Compared with the large number of tumor nodules in the lungs in the PBS group, the tumor nodules were significantly smaller after intravenous injection of RS-Te and NIR laser irradiation, indicated that RS-Te plus laser treatment possessed strong anti-tumor metastasis potential.\u003c/p\u003e\n\u003cp\u003eTo elucidate the mechanism of tumor elimination and anti-tumor metastasis triggered by RS-Te-based phototherapy, 4T1 tumor-bearing mice (five weeks, female) were randomly divided into 4 groups (4 mice/per group). The mice were intravenously injected with PBS, S-Te, and RS-Te, after 24 h post injection. Another group of RS-Te was treated with laser irradiation (1.5 W/cm\u003csup\u003e2\u003c/sup\u003e, 10 min), denoted as PBS, S-Te, RS-Te, and RS-Te\u0026thinsp;+\u0026thinsp;L groups, respectively. DLNs and tumors of mice were collected and analyzed by FCM at 48 h after administration. It is shown that intravenous administration of RS-Te induced the more pronounced proliferation of DCs maturation in DLNs compared with administration of S-Te, indicating that the delivery system of macrophages carrying mineralized bacteria had a stronger immune activation capacity than that of bacterial vectors alone (Additional file 1: Fig. S9). More importantly, RS-Te plus laser treatment led to further DC maturation, and a similar trend of mature DC proportion was observed in tumors of each group, illustrating that the combination of Te-based photothermal killing and biomimetic strategy could synergistically contribute to DC maturation (Additional file 1: Fig. S10). The population of tumor-infiltrating effector T lymphocytes (CD3\u003csup\u003e+\u003c/sup\u003e CD4\u003csup\u003e+\u003c/sup\u003e T cells and CD3\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003e T cells) in total T cells and Tregs in the tumor tissues after treatments were measured. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eH, although the level of CD3\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003eT cells in S-Te group was elevated relative to the PBS group, the level of CD3\u003csup\u003e+\u003c/sup\u003e CD8\u003csup\u003e+\u003c/sup\u003eT cells increase was more significant in RS-Te and RS-Te\u0026thinsp;+\u0026thinsp;L groups, where the level of CD3\u003csup\u003e+\u003c/sup\u003eCD8\u003csup\u003e+\u003c/sup\u003eT cells in RS-Te\u0026thinsp;+\u0026thinsp;L group was 4.84, 2.54, and 1.32 times higher than that of the PBS, S-Te, and RS-Te groups, respectively. A similar change trend of CD3\u003csup\u003e+\u003c/sup\u003eCD4\u003csup\u003e+\u003c/sup\u003eT cells in tumor tissues was also found (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eI). In contrast, Tregs that play an important role in immune suppression showed a 5.64-fold reduction relative to the PBS group (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eJ). Moreover, the level of TAMs in tumors was confirmed by measuring the protein markers from macrophage cell surfaces, including CD80\u003csup\u003e+\u003c/sup\u003e CD86\u003csup\u003e+\u003c/sup\u003e and CD80\u003csup\u003e+\u003c/sup\u003e CD206\u003csup\u003e+\u003c/sup\u003e. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eK, L, RS-Te treating boosted the percentage of CD80\u003csup\u003e+\u003c/sup\u003e CD86\u003csup\u003e+\u003c/sup\u003e with a rate of 17.03%, which was 12.05% in the PBS group and 14.69% in the S-Te group. It is also observed that RS-Te plus NIR laser treatment caused the highest proportion (22.98%) of CD80\u003csup\u003e+\u003c/sup\u003e CD86\u003csup\u003e+\u003c/sup\u003e, which might be Sal, such as by carrying shRNA against a critical gene of metastasis or upregulating tumor genes, expressing effector proteins, such as IFN-\u0026gamma; [\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e]. The IFN-\u0026gamma; was subsequently examined, and the level of IFN-\u0026gamma; obviously increased in the RS-Te\u0026thinsp;+\u0026thinsp;laser group (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eM). In addition, the serum levels of TNF-\u0026alpha; and IL-6 in the RS-Te\u0026thinsp;+\u0026thinsp;laser group were also remarkably aggrandized (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eN, O), which are consistent with the \u003cem\u003ein vitro\u003c/em\u003e results. All these results verify that RS-Te could efficiently reprogram the immunosuppressive TME and induce strong CD8\u003csup\u003e+\u003c/sup\u003e and CD4\u003csup\u003e+\u003c/sup\u003e T cells immune response, attributing to the significantly augmented macrophage polarization, \u003cem\u003ein situ\u003c/em\u003e tumor-associated antigens (TAAs) release and presentation, and pro-inflammatory factor regulation, and these responses were further reinforced under NIR laser irradiation.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn our study, RAW264.7 cells served as a carrier for Sal, providing protection against the host immune system and facilitating targeted delivery of Sal to the tumor core. Additionally, macrophage-camouflaged bacteria effectively evaded adverse immune reactions that would occur with bacteria alone. TeNPs were mineralized within Sal, thereby inhibiting bacterial proliferation and reducing potential safety hazards associated with bacterial multiplication. Moreover, TeNPs exhibited excellent photothermal conversion properties and enabled effective photothermal elimination of tumors. \u003cem\u003eIn vivo\u003c/em\u003e experiments demonstrated that this double-camouflaged delivery system exposed TAAs through NIR-triggered PTT, stimulated DCs maturation using TAAs, Sal, and M1 macrophages, promoted cytotoxic T cell priming and infiltration into tumors, reprogrammed TAMs, reversed the immunosuppressive tumor microenvironment to antitumor immunity. This RS-Te delivery platform achieved a perfect balance between safety and therapeutic efficacy by utilizing an autogenous vector for the bacterial immune adjuvant. Overall, the RS-Te platform enhanced tumor targeting efficiency and therapeutic effects while improving safety aspects in cancer treatment through synergistic interactions among immune cells, bacteria, and inorganic nanomaterials.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll animal experiments were approved by the Animal Experimental Ethics Committee of Hubei University of Chinese Medicine (SYXK 2023-0067).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors agree to publish this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analyzed during this study were included in this published article (and its additional files).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCL designed and carried out the experiments. LY carried out the characterization of materials. BZ performed cell extraction and culture in vitro. JL touched up the picture. BC analyzed the radiographic and histological data. WN interpreted the experimental data. GZ provided financial support and examined manuscripts.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing financial interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the project funded by China Postdoctoral Science Foundation (2023M731042) and Knowledge Innovation Project in Wuhan, Hubei Province, China (2023020201020472).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003ePan W, Liu C, Li YH, Yang YH, Li WL, Feng C, Li LJ. Ultrathin tellurium nanosheets for simultaneous cancer thermo-chemotherapy. Bioact Mater. 2022; 13: 96-104.\u003c/li\u003e\n\u003cli\u003eLi CQ, Hou XL, Jiang DX, Zhang B, Ma MW, Xie XT, Zhao YD, Liu TC, Liu B. Binary Pt/Te nanoheterostructures with high photothermal conversion efficiency and anti-inflammatory action for enhanced photothermal therapy of 4T1 breast tumors guided by photoacoustic imaging. ACS Sustainable Chem Eng\u003cem\u003e.\u003c/em\u003e 2022; 10: 16598-610.\u003c/li\u003e\n\u003cli\u003eHuang XH, Pan JM, Xu FN, Shao BF, Wang Y, Guo X, Zhou SB. Bacteria-based cancer immunotherapy. Adv Sci. 2021; 8: 2003572.\u003c/li\u003e\n\u003cli\u003eFan JX, Niu MT, Qin YT, Sun YX, Zhang XZ. Progress of engineered bacteria for tumor therapy. Adv Drug Deliver Rev. 2022; 185: 114296.\u003c/li\u003e\n\u003cli\u003eChen QW, Liu XH, Fan JX, Peng SY, Wang JW, Wang XN, Zhang C, Liu CJ, Zhang XZ. Self-mineralized photothermal bacteria hybridizing with mitochondria-targeted metal-organic frameworks for augmenting photothermal tumor therapy. Adv Mater. 2020; 30: 1909806.\u003c/li\u003e\n\u003cli\u003eTian Lj, Min Y, Li WW, Chen JJ, Zhou NQ, Zhu TT, Li DB, Ma JY, An PF, Zheng LR, Huang H, Liu YZ, Yu HQ. Substrate metabolism-driven assembly of high-quality CdS\u003csub\u003ex\u003c/sub\u003eSe\u003csub\u003e1-x\u003c/sub\u003e quantum dots in escherichia coli: molecular mechanisms and bioimaging application. ACS Nano\u003cem\u003e \u003c/em\u003e2019; 13: 5841-51.\u003c/li\u003e\n\u003cli\u003eBeatriz GG, Mario CR, Ma TPC, J\u0026ouml;rg B, Mar\u0026iacute;a MB, Yolanda M. Combined single cell and single particle ICP-TQ-MS analysis to quantitatively evaluate the uptake and biotransformation of tellurium nanoparticles in bacteria. Anal Chim Acta 2020; 1128: 116-28.\u003c/li\u003e\n\u003cli\u003eGuo YX, Chen Y, Liu XQ, Min JJ, Tan WZ, Zheng JH. Targeted cancer immunotherapy with genetically engineered oncolytic salmonella typhimurium. Cancer Lett 2020; 469: 102-10.\u003c/li\u003e\n\u003cli\u003eLuzuriaga MA, Herbert FC, Brohlin OR, Gadhvi J, Howlett T, Shahrivarkevishahi A, Wijesundara YH, Venkitapathi S, Veera K, Ehrman R, Benjamin CE, Popal S, Burton MD, Ingersoll MA, Nisco NJD, Gassensmith JJ. Metal-organic framework encapsulated whole-cell vaccines enhance humoral immunity against bacterial infection. ACS Nano 2021; 15: 17426-438.\u003c/li\u003e\n\u003cli\u003eCao ZP, Cheng SS, Wang XY, Pang Y, Liu JY. Camouflaging bacteria by wrapping with cell membranes. Nat Commun. 2019; 10: 3452.\u003c/li\u003e\n\u003cli\u003eLi CQ, Ma MW, Zhang B, Chen W, Yin ZY, Xie XT, Hou XL, Zhao YD, Liu B. A Self-assembled nanoplatform based on Ag\u003csub\u003e2\u003c/sub\u003eS quantum dots and tellurium nanorods for combined chemo-photothermal therapy guided by H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e-activated near-infrared-II fluorescence imaging. Acta Biomater. 2022; 140: 547-60.\u003c/li\u003e\n\u003cli\u003eOved JH, Barrett DM, Teachey DT. Cellular therapy: immune-related complications. Immunol Rev. 2019; 290: 114-26.\u003c/li\u003e\n\u003cli\u003eRezvani K. Adoptive cell therapy using engineered natural killer cells. Bone Marrow Transpl. 2019; 54: 785-88.\u003c/li\u003e\n\u003cli\u003eWang C, Wang YL, Zhang LL, Miron RJ, Liang JF, Shi MS, Mo WT, Zheng SH, Zhao YB, Zhang YF. Pretreated macrophage-membrane-coated gold nanocages for precise drug delivery for treatment of bacterial infections. Adv Mater. 2018; 30: 1804023.\u003c/li\u003e\n\u003cli\u003eOved JH, Barrett DM, Teachey DT. Cellular therapy: immune-related complications. Immunol Rev. 2019; 290: 114-26.\u003c/li\u003e\n\u003cli\u003eXiong LH, Cui, R.; Zhang ZL, Cui R, Shi YB, Pang DW. Harnessing intracellular biochemical pathways for \u003cem\u003ein vitro \u003c/em\u003esynthesis of designer tellurium nanorods. Small 2015; 11: 5416-22.\u003c/li\u003e\n\u003cli\u003ePeng J.; Pan Y, Yu Z, Wu JC, Zhou Y, Guo YQ, Wu XJ, Wu CZ, Xie Y. Two-dimensional tellurium nanosheets exhibiting an anomalous switchable photoresponse with thickness dependence. Angew Chem Int Ed. 2018; 57: 13533-537.\u003c/li\u003e\n\u003cli\u003eTurner R, Borghese R, Zannoni D. Microbial processing of tellurium as a tool in biotechnology. Biotechnol Adv. 2012; 30: 954-63.\u003c/li\u003e\n\u003cli\u003eLi CQ, Zhao DH, Hou XL, Zhang B, Song LB, Jin RM, Zhao YD, Liu B. In situ synthesis of multifunctional tellurium nanorods stabilized by polypeptide-engineered for photothermal-sonodynamic combination therapy of tumors. Chem Eng J\u003cem\u003e.\u003c/em\u003e 2021; 417: 127989. \u003c/li\u003e\n\u003cli\u003eSweeney E, Cano-Mejia J, Fernandes R. Photothermal therapy generates a thermal window of immunogenic cell death in neuroblastoma. Small 2018; 14: 1800678.\u003c/li\u003e\n\u003cli\u003eCheng L, Wang C, Feng LZ, Yang K, Liu Z. Functional nanomaterials for phototherapies of cancer. Chem Rev. 2014; 114: 10869-939.\u003c/li\u003e\n\u003cli\u003eZeng J, Goldfeld D, Xia YN. A Plasmon-assisted optofluidic (PAOF) system for measuring the photothermal conversion efficiencies of gold nanostructures and controlling an electrical switch. Angew Chem Int Ed. 2013; 52: 4169-73.\u003c/li\u003e\n\u003cli\u003eLi SS Gu K, Wang H, Xu BL, Li HW, Shi XH, Huang ZJ, Liu HY. Degradable holey palladium nanosheets with highly active 1D nanoholes for synergetic phototherapy of hypoxic tumors. J Am Chem Soc\u003cem\u003e.\u003c/em\u003e 2020; 142: 5649-56.\u003c/li\u003e\n\u003cli\u003eGuo Q, Li XW, Zhou WX, Chu YC, Chen QJ, Zhang YW, Li C, Chen HY, Liu PX, Zhao ZH. Wang Y, Zhou Z, Luo YF, Li CF, You HY, Song HL, Su BY, Zhang TY, Sun T, Jiang Chen. Sequentially triggered bacterial outer membrane vesicles for macrophage metabolism modulation and tumor metastasis suppression. ACS Nano\u003cem\u003e \u003c/em\u003e2021; 15: 13826-38.\u003c/li\u003e\n\u003cli\u003eYue WW, Chen L, Yu LD, Zhou BG, Yin HH, Ren WW, Liu C, Guo LH, Zhang YF, Sun LP, Zhang K, Xu HX, Chen Y. Checkpoint blockade and nanosonosensitizer-augmented noninvasive sonodynamic therapy combination reduces tumor growth and metastases in mice. Nat Commun. 2019; 10: 2025.\u003c/li\u003e\n\u003cli\u003eBa L, D\u0026ouml;ring M, Jamier V, Jacob C. Tellurium: An element with great biological potency and potential. Org. Biomol Chem. 2010; 8: 4203-16.\u003c/li\u003e\n\u003cli\u003eSylvestre M, Crane A, Pun S. Progress on modulating tumor-associated macrophages with biomaterials. Adv Mater. 2020; 32: 1902007.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Scheme","content":"\u003cp\u003eScheme 1 is available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-nanobiotechnology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jnan","sideBox":"Learn more about [Journal of Nanobiotechnology](http://jnanobiotechnology.biomedcentral.com)","snPcode":"12951","submissionUrl":"https://submission.nature.com/new-submission/12951/3","title":"Journal of Nanobiotechnology","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Tellurium nanoparticles, Biomineralization, Biomimetic delivery vector, Macrophages-mediated immunotherapy, Photothermal therapy","lastPublishedDoi":"10.21203/rs.3.rs-4097182/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4097182/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe photothermal conversion properties of tellurium (Te) nanoparticles have been extensively investigated, rendering them a promising candidate for tumor photothermal therapy. However, there is still room for improvement in the development of efficient Te-based drug delivery systems. Here, Te nanoparticles are mineralized with bioactive molecules within attenuated \u003cem\u003eSalmonella\u003c/em\u003e (S-Te), which are subsequently taken up by macrophages (RAW264.7) to construct a double-camouflaged delivery platform (RS-Te). Remarkably, RS-Te retains superior photothermal properties under near-infrared irradiation. The mineralization process eliminates bacterial proliferation potential, thereby mitigating the risk of excessive bacterial growth \u003cem\u003ein vivo\u003c/em\u003e. Furthermore, the uptake of bacteria by macrophages not only polarizes them into M1 macrophages to induce an anti-tumor immune response but also circumvents any adverse effects caused by complex antigens on the bacterial surface. The results show that RS-Te can effectively accumulate and retain in tumors. RS-Te-mediated photothermal immunotherapy largely promotes the maturation of dendritic cells and priming of cytotoxic T cells induced by near-infrared laser irradiation. Moreover, RS-Te can switch the activation of macrophages from an immunosuppressive M2 phenotype to a more inflammatory M1 state. The double-camouflaged delivery system may offer highly efficient and safe cancer treatment.\u003c/p\u003e","manuscriptTitle":"Double-camouflaged tellurium nanoparticles for enhanced photothermal immunotherapy of tumor","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-21 15:01:43","doi":"10.21203/rs.3.rs-4097182/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-06-02T16:19:53+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-04-17T08:42:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"d5c178d0-cd47-466e-a744-91fb263e44c0","date":"2024-04-04T11:19:40+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-04-02T08:45:39+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-03-18T13:58:02+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-03-16T12:50:18+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Nanobiotechnology","date":"2024-03-14T04:22:46+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-nanobiotechnology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jnan","sideBox":"Learn more about [Journal of Nanobiotechnology](http://jnanobiotechnology.biomedcentral.com)","snPcode":"12951","submissionUrl":"https://submission.nature.com/new-submission/12951/3","title":"Journal of Nanobiotechnology","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"6d824ff8-e68e-4ab6-8452-1041d7412987","owner":[],"postedDate":"March 21st, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-10-14T15:59:37+00:00","versionOfRecord":{"articleIdentity":"rs-4097182","link":"https://doi.org/10.1186/s12951-024-02853-2","journal":{"identity":"journal-of-nanobiotechnology","isVorOnly":false,"title":"Journal of Nanobiotechnology"},"publishedOn":"2024-10-08 15:57:06","publishedOnDateReadable":"October 8th, 2024"},"versionCreatedAt":"2024-03-21 15:01:43","video":"","vorDoi":"10.1186/s12951-024-02853-2","vorDoiUrl":"https://doi.org/10.1186/s12951-024-02853-2","workflowStages":[]},"version":"v1","identity":"rs-4097182","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4097182","identity":"rs-4097182","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}