Toward High-Performance Biosensing: Dual-Mode Detection of Biological Thiols via Synergistic Passivation of Perovskite Quantum Dots

Toward High-Performance Biosensing: Dual-Mode Detection of Biological Thiols via Synergistic Passivation of Perovskite Quantum Dots | 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 Toward High-Performance Biosensing: Dual-Mode Detection of Biological Thiols via Synergistic Passivation of Perovskite Quantum Dots Songbing Gao, Qianfeng Li, Haifa Zhai, Gongke Wang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9021008/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 23 Apr, 2026 Read the published version in Microchimica Acta → Version 1 posted 9 You are reading this latest preprint version Abstract Biological thiols (biothiols), such as cysteine (Cys), glutathione (GSH), and homocysteine (Hcy) are essential for maintaining life activities, and their abnormal concentrations are closely associated with various diseases. To overcome the drawbacks of existing detection methods, we developed a dual-mode sensor using synergistically passivated CsPbBr₃ quantum dots (QDs). By introducing the ligand sodium dodecyl sulfate (SDS) into CsPbBr₃ (QDs) and combining the specific recognition ability of 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) toward thiol groups (–SH), a dual-mode detection system was constructed. In the presence of biological thiols, their –SH react with DTNB to generate 2-nitro-5-thiobenzoic acid (TNB). A discernible color change of the solution from light green to yellow, along with fluorescence quenching of the CsPbBr₃@SDS QDs, was observed. This is attributed to the inner-filter effect (IFE), which is initiated by the overlap of the TNB absorption spectrum with the excitation spectrum of the QDs. This enables the dual-mode detection of target analytes via fluorescence and colorimetric signals. The sensor demonstrates high sensitivity toward Cys, GSH, and Hcy, with detection limits as low as 2.63 µM, 3.09 µM, and 2.15 µM, respectively, along with a wide linear range. The sensor also exhibits excellent selectivity and anti-interference capabilities. This work provides an effective strategy for biothiol detection, showing promising application prospects in biomedical diagnosis and environmental monitoring. Co-passivated perovskite quantum dots Dual-mode sensing Biological thiols Water stability Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction Bbiothiols constitute a class of crucial biological small-molecule antioxidants. They play vital supporting roles in numerous physiological processes and serve as indispensable components for ensuring normal biological functions and maintaining human health. These compounds are abundantly present in biological cells, wheat germ, and yeast [1–4]. Biothiols serve as key scavengers for reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂) and lipid peroxides, functioning as essential components within various antioxidant enzymes. They play crucial roles in cellular damage repair, the maintenance of vascular health, and the preservation of protein functional homeostasis [5,6]. The human body relies on exogenous precursors to synthesize biothiols, and these precursors must be obtained through dietary intake. Therefore, a balanced diet is crucial for maintaining good health. Abnormal biothiols concentrations can trigger various diseases. For example, Cys deficiency can lead to skin damage, lethargy, and reduced body fat [7], while elevated Hcy levels are associated with cardiovascular and Alzheimer's diseases. Imbalances in GSH levels may influence the development of cancer, aging, and heart diseases [8]. Currently, the primary methods for detecting biothiols include hydrophilic interaction chromatography coupled with electrospray tandem mass spectrometry (HILIC-MS/MS) [9], electrospray ionization tandem mass spectrometry (ESI-MS/MS) [10,11], and high-performance liquid chromatography (HPLC) [12,13]. Although these methods offer high precision and sensitivity, their complex operation, long processing times, and cumbersome sample preparation procedures limit their application in field testing. Additionally, 5,5'-dithiobis (2-nitrobenzoic acid) (DTNB) is employed for the colorimetric sensing of biothiols because of its specific recognition of –SH [14, 15], as demonstrated in the DTNB-gold nanoparticle (DTNB–AuNP) colorimetric sensor developed by Mustafa et al [14]. However, the aggregation of AuNPs in complex biological samples can lead to false positives, and their limited sensitivity hinders their practical application. Therefore, a convenient, highly accurate, and selective detection method for biothiols is urgently needed. All-inorganic perovskite quantum dots (CsPbX₃ QDs) serve as ideal fluorescent probes for the detection of biological thiols, owing to their high sensitivity, cost-effectiveness, strong selectivity, ease of operation, and non-destructive nature. However, CsPbX₃ QDs exhibit poor stability in polar media, particularly aqueous solutions, which limits their applications [16]. Although strategies such as the water emulsion method, ligand reconfiguration, and recrystallization have been employed to enhance their water solubility, challenges remain, including complex operations, the use of toxic reagents, and colloidal instability [17]. Therefore, exploring simple, green, and stable CsPbX3 QD-based sensing technologies remains a key focus of current research. To address these challenges, we designed a multi-ligand passivation strategy. In this study, multifunctional ligands were used to synergistically passivate CsPbX3. The introduction of 4-bromobutyric acid (BBA), oleylamine (OLA), and sodium dodecyl sulfate (SDS) ligands formed an external hydrophobic protective shell on the surface of the CsPbBr₃ QDs. This effectively inhibits the intrusion of water molecules and enhances their resistance to decomposition in aqueous environments, enabling stable emissions for up to 120 h. Therefore, a fluorescent sensor based on the CsPbBr₃@SDS QDs and DTNB composite system was constructed, as shown in Scheme 1 . CsPbBr₃@SDS QDs emit green light at 520 nm when excited at 365 nm, forming a stable fluorescent system upon complexation with DTNB. Leveraging the selective recognition of thiol groups by DTNB, biothiols induce fluorescence quenching in CsPbBr₃@SDS QDs via an inner-filter effect (IFE), accompanied by a color shift from light green to yellow in solution. This enables the dual-mode fluorescence–colorimetric detection of biothiols. The fluorescent sensor developed by our research institute exhibiteds high sensitivity and strong anti-interference capabilities. GSH, Cys, and HCy were successfully detected in biological samples (such as human blood serum), offering a promising exploratory approach for the application of CsPbX₃ QDs in the field of life sciences and health. 2. Experimental 2.1. Materials and reagents Chemical reagents were procured from two primary suppliers. Aladdin Biochemical Technology Co., Ltd. (Shanghai, China) provided the synthesis materials: lead bromide (PbBr₂, 98%), cesium bromide (CsBr, 99%), oleylamine (OLA, 90%), oleic acid (OA), 1-octadecene (ODE), as well as ligands and modifiers including sodium dodecyl sulfate (SDS), 4-bromobutyric acid (BBA), and (3-aminopropyl) trimethoxysilane (3-APTMS), alongside solvents (DMA, DMF) and hydrochloric acid (HCl). Glutathione, cysteine, homocysteine, and related amino acids were obtained from Macklin (Shanghai, China). All chemicals were utilized directly without additional purification steps. 2.2. Characterization The crystalline phases of the prepared samples were identified using a Panalytical X'Pert3 Powder X-ray diffractometer (XRD). XRD instrument employed graphite monochromatic Cu-Kα radiation (λ = 0.15418 nm) with a scan step size of 0.02° and a scan range from 10° to 80°. We employed two distinct spectrophotometers for optical analyses. A Beijing Purkinje TU-1810 UV–Vis spectrophotometer was used to measure sample absorption, and a Varian CARY Eclipse fluorescence spectrophotometer was utilized to acquire the steady-state photoluminescence (PL) spectra. All fluorescence spectra were recorded with the excitation and emission slit widths fixed at 5 nm. The transient fluorescence spectra were acquired using an Edinburgh Instruments FLS980 instrument. X-ray photoelectron spectroscopy (XPS) was performed using an ESCALAB 250Xi instrument (Thermo Fisher Scientific, USA). The Fourier transform infrared spectra (FT-IR) was performed using the KBr pellet technique in transmission mode over 4000–500 cm⁻¹ with a Bio-Rad (USA) instrument. Infrared spectra were obtained using a Bruker FTS-40 instrument. A JEM-2100 transmission electron microscope (JEOL, Tokyo, Japan) was employed for obtaining TEM images of the samples. The nanoparticle size was measured using a Zetasizer Pro (Malvern PANalytical Ltd.). 2.3. Preparation of CsPbBr₃ QDs The synthesis in this study was based on a ligand-assisted precipitation method reported in the literature, with appropriate modifications and improvements [18]. PbBr₂ (0.4 mmol) and CsBr (0.4 mmol) were successively dissolved in 10 mL of DMF in a transparent vial under constant temperature stirring for 1 h. Subsequently, OLA and BBA were sequentially injected rapidly into the above solution. The solution was then stirred under constant heating for 20 min to ensure complete reaction of the ligands. Subsequently, 2 mL of the precursor solution was added to 25 mL of the water solution. After the reaction, the mixture was centrifuged to remove the precipitate. The collected supernatant was subjected to high-speed centrifugation to obtain a clear solution. The final CsPbBr3@BBA QDs were stored at 4°C for future use. 2.4. Synthesis of CsPbBr₃@SDS QDs. Both PbBr₂ (146.8 mg) and CsBr (85.1 mg) were added to a glass reaction flask containing 10 mL of DMA solution. After mixing, constant stirring was maintained at a constant temperature in a water bath for 45 min. Under vigorous stirring, OLA (0.3 mL), BBA (0.3 mL), and a DMA solution containing the SDS ligand (2 mmol) were added. Stirring until a pale-yellow emulsion was formed. Subsequently, a small amount of the prepared emulsion was injected into pure water. The precipitate was removed by centrifugation. Finally, the supernatant was stored in a refrigerator for subsequent experiments. Air recrystallization was employed throughout the entire synthetic process, and no noble gas was introduced at any stage. 2.5. Fluorescent detection of biothiols The experimental procedure in which the fluorescent sensor detects biothiols is as follows: first, 300 µL of target analyte solutions at different concentrations (Tris-HCl buffer, 0.01 M) or blank control solution was added to the reaction system. The reaction system was prepared by combining CsPbBr₃@SDS QDs (in Tris-HCl buffer) with 100 µL of 1 mM DTNB. The mixed solution was thoroughly shaken and incubatd at room temperature to ensure a complete reaction.A fluorescence spectrophotometer, with an excitation wavelength set at 365 nm, was employed to record the emission spectra of all samples, and both the excitation and emission slit widths were set to 5 nm. Simultaneously, a UV–Vis spectrophotometer measured the fluorescence absorption peaks before and after the addition the target analyte. 2.6. Selectivity and interference tests Anti-interference experiments were preformed to evaluate the applicability of the sensor in complex systems. The experiment selected several common amino acids (aspartic acid (Asp), histidine (His), serine (Ser), alanine (Ala), valine (Val), threonine (Thr), phenylalanine (Phe), isoleucine (Iso), and arginine (Arg)), along with inorganic ions (NO₃⁻, Cl⁻, SO₄²⁻, K⁺, Na⁺, Ca²⁺, Zn²⁺, and Mg²⁺) as potential interferents. The antioxidant vitamin C (VC) was also introduced to further investigate its effects. 2.7. Disposal of real samples Fluorescence and colorimetric methods employed in this study were used to detect biothiols in human blood serum samples. Healthy human blood serum samples (Solarbio Tech Co., Ltd.) were immediately frozen upon collection to maintain their stability and biological activity for experimental use. Before analysis, serum samples were diluted 1:30 with 0.01 M Tris-HCl buffer (pH = 7.0) to minimize matrix effects on the detection results. Subsequently, add 10, 20, and 30 µM biothiols standard solutions to the diluted serum. The samples were analyzed using a fluorescence detection method based on the IFE to evaluate the detection performance of the sensor. 3. Results and discussion 3.1. Characterization of CsPbBr3@SDS QDs Analysis was performed using multiple characterization methods, including fluorescence spectroscopy, UV–Vis spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy, the structure and optical properties of CsPbBr₃@SDS QDs were systematically investigated, confirming their successful preparation. TEM analysis (Fig. 1 a and 1 b) indicates that the obtained CsPbBr₃@SDS QDs exhibit good dispersion and size uniformity, with an average particle size of approximately 30.68 ± 3.18 nm. High-resolution TEM images clearly reveal lattice fringes with a spacing of 0.42 nm, corresponding to the [110] crystal plane of cubic CsPbBr₃ [19], indicating that aqueous-phase synthesis did not affect its intrinsic crystal structure. Furthermore, the introduction of SDS plays a crucial role in stabilizing CsPbBr₃ QDs. SDS-protected QDs (CsPbBr₃@SDS) retain excellent monodispersity and form aggregates composed of 7–9 CsPbBr₃ QDs, indicating that SDS maintains the crystal structure of CsPbBr₃ QDs even after encapsulation. The long carbon chains in SDS molecules aggregate CsPbBr₃ QDs through the hydrophobic effect, while the hydrophilic sulfate ester groups face the aqueous phase, inhibiting water molecule penetration. This enhances the physicochemical stability and anti-disintegration properties of CsPbBr₃@SDS QDs. XRD (Fig. 1 c) further confirmed the crystal structure of CsPbBr₃@SDS QDs. Their diffraction peaks perfectly matched the cubic perovskite structure of standard CsPbBr₃ (PDF#18–0364), indicating that SDS encapsulation did not alter its crystal phase. FT-IR spectroscopy (Fig. 1 d) detected an S = O stretching vibration peak at 1036 cm⁻¹, indicating that SDS molecules were successfully modified onto the surface of CsPbBr₃ QDs, participated in the formation of surface states, and effectively enhanced the stability of the QDs. XPS analysis further validated the surface modification effect of SDS on CsPbBr₃@SDS QDs. As shown in Fig. 1 e, the O 1s signal of CsPbBr₃@SDS QDs exhibited S-O-related peaks in the high-resolution O 1s spectrum, indicating chemical bonding between SDS molecules and CsPbBr₃ QDs. Compared with unmodified CsPbBr₃ QDs, the O-C-O and C-O binding energies in CsPbBr₃@SDS QDs exhibited shifts, further demonstrating the formation of stable coordination structures on the QD surface by SDS [20, 21]. The shift in the peak positions observed in the XPS spectrum (Fig. S1 ) further indicates an interaction between CsPbBr₃ QDs and SDS, in agreement with the work of Zhang et al [22]. Through multiple spectroscopic and structural characterization techniques, we verified the successful surface modification of SDS on CsPbBr₃ QDs, significantly enhancing their water stability and optical properties. This strategy provides an effective approach for preparing stable and efficient QDs in aqueous solutions. 3.2. Stability assessment of CsPbBr3@SDS QDs As shown in the UV-Vis and fluorescence spectra of CsPbBr₃ and CsPbBr₃@SDS QDs (Fig. 2 a), CsPbBr₃ QDs exhibit weak green fluorescence emission at 521 nm upon 365 nm excitation. However, the fluorescence intensity is significantly enhanced in aqueous solution upon modification with SDS ligands, indicating that SDS markedly optimizes the optical properties of CsPbBr₃ QDs. As shown in Fig. 2 b, compared with the slightly turbid solution formed by CsPbBr₃ QDs, the solution formed by CsPbBr₃@SDS QDs exhibits high transparency, indicating superior dispersibility and stability in aqueous environments. Further studies revealed that even after 120 h in the water solution, CsPbBr₃@SDS QDs retained strong green fluorescence (Fig. 2 c), demonstrating excellent water stability. This enhanced water solubility and degradation resistance likely stems from two mechanisms: (1) the oxygen atoms in the sulfate ester group of SDS molecules form coordination bonds with Pb²⁺ ions [23], effectively reducing surface vacancy defects and thereby enhancing the photostability of QDs and (2) the external hydrophobic shell formed by SDS on the CsPbBr₃ QD surface effectively inhibits water molecule intrusion, further strengthening the hydrolysis resistance of the material. The prepared CsPbBr₃@SDS QDs exhibit outstanding optical stability in aqueous environments, maintaining excellent fluorescence properties even under varying dilution conditions. Their robust resistance to degradation and environmental adaptability offer broad potential applications in aqueous detection, bioimaging, and other optical fields. 3.3. Feasibility analysis of biothiol detection and mechanism of fluorescence detection Figure 3 a shows that the excitation peak of CsPbBr₃@SDS QDs is located at 264 nm, with a fluorescence emission peak at 520 nm, while TNB exhibits a strong and broad absorption peak at 347 nm. Notably, the excitation peak of CsPbBr₃@SDS QDs overlaps to some extent with the absorption peak of TNB. The presence of Cys has a negligible impact on the fluorescence of CsPbBr₃@SDS QDs, as evidenced by their sustained strong green emission shown in Fig. 3 b. However, the addition of DTNB leads to a considerable drop in the fluorescence intensity exhibited by CsPbBr₃@SDS QDs, which may be attributed to the partial decomposition of DTNB into TNB. Further analysis revealed that when Cys was added to the CsPbBr₃@SDS QDs and DTNB mixture, –SH of Cys reacted with DTNB to form yellow TNB. Owing to the strong absorption of TNB at 347 nm and its ability to absorb the excitation light at 264 nm, this reaction triggers fluorescence quenching. As shown in Fig. 3 d, both CsPbBr₃@SDS QDs and TNB exhibit positive charges; thus, the conditions for electrostatic adsorption are not met and TNB is unable to bind to the QD surface. This excludes the possibility of a fluorescence resonance energy transfer (FRET) mechanism. The fluorescence lifetime analysis further confirmed the fluorescence quenching mechanism of the sensor. As shown in Fig. 3 c, the fluorescence lifetime of CsPbBr₃@SDS QDs was 138.81 ns, and no significant decay was observed after incubation with DTNB (136.57 ns) or DTNB/Cys (135.24 ns). This phenomenon indicates that CsPbBr₃@SDS QDs primarily undergo static quenching rather than dynamic quenching during the fluorescence quenching process [24, 25]. Therefore, the fluorescence quenching can be inferred to originate primarily from IFE rather than from FRET. These results demonstrate that the prepared sensor system can effectively detect biothiols and provide reliable theoretical support for the highly sensitive detection of biothiols. 3.4. Optimization of the detection system The effects of incubation time, temperature, and Tris-HCl buffer pH on the sensitivity and stability of the fluorescent sensor were systematically investigated to optimize its performance for biothiol detection. The influence of incubation time was assessed by monitoring the fluorescence intensity at 521 nm was evaluated, as shown in Fig. S2a, 2d and 2g. with incubation times ranging from 0 to 40 min. Following the introduction of the three biothiols, a rapid and notable fluorescence response ensued. After 1 min of incubation, the fluorescence intensity decreased significantly, and the signal stabilized within 5 min, indicating that the reaction had essentially reached equilibrium. Considering both the detection efficiency and experimental precision, 5 min was ultimately determined as the optimal incubation time to meet the rapid testing requirements. Fig. S2b, 2e and 2h illustrates the detection performance of the sensor was evaluated under different Tris-HCl buffer pH conditions. Within the pH range of 3.0–7.0, the fluorescence intensity gradually increased with increasing pH. Conversely, in the pH range of 7.0–9.0, the fluorescence intensity progressively decreased as the pH increased. The oxidation of biothiols under high pH conditions, along with alterations in the stability of the sensing system, may both contribute to this phenomenon. Based on this, the pH of the detection system was set to 7.0 for all subsequent experiments. Fig. S2c, 2f and 2i further illustrates the effect of different ambient temperatures on the detection performance of the sensor. The experimental results indicate that the fluorescence intensity exhibits the most pronounced variation at 25°C (room temperature). As the temperature increases, the fluorescence intensity of the sensing system gradually decreases, and the magnitude of the fluorescence intensity change diminishes upon target addition. This may be attributed to the enhanced non-radiative transitions of QDs at elevated temperatures, leading to intensified fluorescence quenching effects and consequently reduced detection sensitivity. Therefore, room temperature (25°C) was determined to be the optimal detection temperature for this sensing system to ensure its sensitivity and stability in practical applications. In summary, a pH = 7.0 aqueous environment, a 5-min incubation period, and detection at 25°C were established as the optimal experimental conditions for detecting biothiols. This optimization strategy not only enhances the sensitivity and stability of the sensor but also ensures its practical applicability in real-world scenarios, providing a reliable experimental foundation for further expanding its use in biomedical and environmental monitoring applications. 3.5. Target detection After optimizing the detection conditions, the system was used to evaluate the performance of this fluorescent sensor in detecting biothiols. As shown in Fig. 4 a, the sensor exhibits distinct fluorescence emission peaks after incubation with different concentrations of Cys, and the fluorescence intensity gradually decreases as the Cys concentration increases. With the detection range spanning 0–100 µM. Figure 4 b further reveals a good linear relationship between the change in fluorescence intensity (ΔF) and Cys concentration, exhibiting high correlation (R² = 0.997) within the range of 0.05–40 µM ,with a detection limit of 2.63 µM. The linear regression equation is ΔF = 12.92CCys + 5.54, where ΔF represents the change in fluorescence intensity (ΔF = F (CsPbBr₃@SDS QDs/DTNB) – F (CsPbBr₃@SDS QDs/DTNB/analyte), and C denotes the Cys concentration (µM). The linear detection ranges for GSH and Hcy are 0.5–40 µM, with detection limits of 3.09 µM and 2.15 µM, respectively. This demonstrates that the sensor exhibits excellent sensitivity and stability when detecting different biothiols (Fig. 5 a, 5 b and Fig. 6 a, 6 b). To further investigate the detection mechanism, the UV–Vis absorption spectra of CsPbBr₃@SDS QDs/DTNB were analyzed at different Cys concentrations (0–100 µM) (Fig. 4 c). As the Cys concentration increases, the characteristic absorption peak at 412 nm gradually intensifies, exhibiting a good linear relationship within the range of 0–40 µM (R² = 0.996), with a detection limit of 0.92 µM (Fig. 4 d). Similarly, GSH exhibited a stable linear relationship within the range of 0–40 µM (R² = 0.991), with a detection limit of 0.74 µM (Fig. 5 c and 5 d), while Hcy also demonstrated a good linear response within 0.1–40 µM (R² = 0.991), with a detection limit of 0.82 µM (Fig. 6 c and 6 d). These results further validate the detection mechanism of the fluorescent sensor and demonstrate its feasibility for detecting biothiols. As shown in Table S1 , this sensor demonstrates superior performance in terms of sensitivity and detection limit compared to previously reported sensors. This exceptional detection capability is primarily attributed to the highly efficient reaction mechanism between the biothiols and DTNB. Furthermore, the optimized detection procedure and simplified operational steps further enhance its feasibility and stability in practical applications. Overall, this fluorescent sensor not only exhibits high sensitivity, rapid response, and excellent selectivity but also demonstrates significant advantages in detection reliability and application scalability, providing a flexible and efficient solution for the effective detection of biothiols. 3.6. Selective interference studies This study employed a fluorescence detection method to measure multiple common amino acids (aspartic acid (Asp), histidine (His), serine (Ser), alanine (Ala), valine (Val), threonine (Thr), phenylalanine (Phe), isoleucine (Iso), and arginine (Arg)), as well as inorganic ions (NO₃⁻, Cl⁻, SO₄²⁻, K⁺, Na⁺, Ca²⁺, Zn²⁺, and Mg²⁺). After incubating the CsPbBr₃@SDS QDs sensing system with different analytes for 5 min, the changes in the fluorescence intensity at 521 nm were measured. As shown in Fig. 7 a, Cys, GSH, and Hcy (40 µM) all significantly induce fluorescence quenching, while other potential interferents do not cause noticeable fluorescence changes even at higher concentrations (2 mM). This phenomenon is primarily attributed to the specific interaction between –SH in biothiols and DTNB, whereas other coexisting substances cannot participate in this reaction and thus do not affect the fluorescence signal. Figure 7 b demonstrates that the presence of biothiols does not affect the corresponding fluorescence changes of the CsPbBr₃@SDS QDs and DTNB mixture toward various analytes. This sensor exhibits exceptional selectivity toward biothiols and possesses outstanding interference resistance, providing reliable assurance for highly sensitive detection in complex biological systems. 3.7. Analysis of real samples Experimental results indicated excellent selectivity of the CsPbBr₃@SDS QDs and DTNB-based fluorescence sensor toward biothiols.To evaluate the detection performance and applicability of the sensor in complex biological samples, authentic human blood serum samples were tested. A fluorescence-based detection method utilizing IFE to quantitatively analyze the biothiol content was employed. To further validate the applicability of the sensor for complex biological samples, experiments were conducted using fluorescence and colorimetric methods to detect human blood serum samples spiked with various concentrations of Cys, GSH, and Hcy. The results are summarized in Table 1 and Table 2 . The detection method demonstrated high accuracy and stability, evidenced by sample recovery rates close to 100% and excellent reproducibility. Together, these data establish both the feasibility of biothiol analysis with the prepared fluorescent sensor and its capability for dual-mode detection. Table 1 Detection of Biothiols in Human Blood Serum Samples (n = 3, Fluorescence Method) Sample Added(µM) Found(µM) Recovery(%) RSD(%, n = 3) Cys 10.0 10.32 ± 0.40 99.22–107.16 1.47 20.0 20.76 ± 0.42 101.69–105.89 1.74 30.0 29.49 ± 0.14 97.84–98.78 0.92 GSH 10.0 10.13 ± 0.44 96.91–105.75 1.27 20.0 19.88 ± 0.68 96.02–102.78 2.70 30.0 30.77 ± 0.38 101.28–103.84 2.71 Hcy 10.0 9.98 ± 0.59 93.93–105.67 1.68 20.0 20.17 ± 0.32 99.24–102.48 1.31 30.0 29.93 ± 0.72 97.36–102.14 4.79 Table 2 Detection of Biothiols in Human Blood Serum Samples (n = 3, Colorimetric Method) Sample Added(µM) Found(µM) Recovery(%) RSD(%, n = 3) Cys 10.0 1047 ± 0.65 98.19–111.17 1.61 20.0 20.42 ± 0.37 100.25–103.99 0.75 30.0 29.95 ± 1.12 96.08–103.58 1.88 GSH 10.0 10.03 ± 0.37 96.6–104.1 0.94 20.0 19.77 ± 0.67 97.00–100.74 0.77 30.0 31.03 ± 0.42 102.18–104.68 0.62 Hcy 10.0 9.82 ± 0.65 94.43–101.93 1.64 20.0 20.21 ± 0.26 97.79–104.29 1.30 30.0 29.93 ± 0.72 99.83–104.15 1.08 4. Conclusion This study proposes a surface confinement strategy that effectively suppresses QD disintegration by encapsulating CsPbBr₃ QDs with SDS in an aqueous medium. The long flexible carbon chains of SDS form hydrophobic association structures around the QD, thereby constructing a stable hydrophobic encapsulation shell that effectively passivates surface defects and optimizes their local environment. Furthermore, the sulfate groups in SDS molecules further promote the modification of surface defects by forming coordination bonds with Pb²⁺ ions. This strategy significantly enhances the water stability of CsPbBr₃@SDS QDs while preserving their outstanding optical properties and high fluorescence quantum yield. We have successfully developed a bio-mercury-responsive fluorescent sensor based on the CsPbBr₃@SDS QDs and DTNB system, providing a novel research direction for the analytical application of perovskite nanocrystals in aqueous environments. The high sensitivity and selectivity of this sensor primarily stem from the specific reaction between –SH in the biothiols and DTNB. Capable of dual-mode detection via both fluorescence and colorimetric methods, the sensor demonstrates excellent repeatability, stability, and resistance to interference. This work established an effective strategy for the efficient detection of biothiols using the developed fluorescence-based sensor, with potential applications in fields such as bioanalysis, medical diagnostics, and environmental monitoring. Declarations Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Conflicts of Interest The authors declare no conflict interests. Funding This work was financially supported by the National Natural Science Foundation of China (No. 22573028) and Natural Science Foundation of Henan Province (No. 252300420250). Author Contribution **Songbing Gao** : Investigation, Writing-original draft, Data analysis. **Qianfeng Li** : Investigation, Software, Data curation. **Haifa Zhai** : Project administration, Validation, Formal analysis. **Gongke Wang** : Conceptualization, Methodology, Supervision, Writing–review & editing, Resources, Funding acquisition. Data Availability Data will be made available on request. References Zu Y (2009) Molecular and nanoparticle postcolumn reagents for assay of low-molecular-mass biothiols using high-performance liquid chromatography. J Chromatogr B 877:3358–3365. https://doi.org/10.1016/j.jchromb.2009.04.031 Isokawa M, Kanamori T, Funatsu T, Tsunoda M (2014) Analytical methods involving separation techniques for determination of low-molecular-weight biothiols in human plasma and blood. 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Nat Energy 8:372–380. https://doi.org/10.1038/s41560-023-01220-z Li Q, Sun J, Li X, et al (2024) Fluorescent nanosensor platform based on CdTe QDs-aptamer probe and MoS2 nanosheets for detection of silver(Ⅰ) ions. Microchem J 206:111376. https://doi.org/10.1016/j.microc.2024.111376 Yang J, Wu H, Yang P, et al (2018) A high performance N-doped carbon quantum dots/5,5′-dithiobis-(2-nitrobenzoic acid) fluorescent sensor for biothiols detection. Sens Actuators B Chem 255:3179–3186. https://doi.org/10.1016/j.snb.2017.09.143 Scheme Scheme 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Supplementary.docx graphicalabstract.png Scheme 1. Schematic illustration of the synthesis of CsPbBr₃@SDS QDs and the dual-mode detection mechanism of the biothiol sensing system. Cite Share Download PDF Status: Published Journal Publication published 23 Apr, 2026 Read the published version in Microchimica Acta → Version 1 posted Editorial decision: Revision requested 01 Apr, 2026 Reviews received at journal 01 Apr, 2026 Reviewers agreed at journal 17 Mar, 2026 Reviews received at journal 11 Mar, 2026 Reviewers agreed at journal 09 Mar, 2026 Reviewers invited by journal 09 Mar, 2026 Editor assigned by journal 05 Mar, 2026 Submission checks completed at journal 05 Mar, 2026 First submitted to journal 03 Mar, 2026 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. 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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-9021008","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":604525302,"identity":"9134aceb-d503-4fae-8327-b49da9540aca","order_by":0,"name":"Songbing Gao","email":"","orcid":"","institution":"Henan Normal University","correspondingAuthor":false,"prefix":"","firstName":"Songbing","middleName":"","lastName":"Gao","suffix":""},{"id":604525303,"identity":"cf717d81-2dbc-4a47-b551-229c46c974cf","order_by":1,"name":"Qianfeng Li","email":"","orcid":"","institution":"Henan Normal University","correspondingAuthor":false,"prefix":"","firstName":"Qianfeng","middleName":"","lastName":"Li","suffix":""},{"id":604525304,"identity":"ac158023-271f-43ac-bbf2-f52c7d778461","order_by":2,"name":"Haifa Zhai","email":"","orcid":"","institution":"Henan Normal University","correspondingAuthor":false,"prefix":"","firstName":"Haifa","middleName":"","lastName":"Zhai","suffix":""},{"id":604525305,"identity":"8a415a25-f973-4c13-9253-dbda4d2b1e48","order_by":3,"name":"Gongke Wang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2ElEQVRIiWNgGAWjYDADCQbmAwc+VJCmhS3x4IwzpGnhMT7M20KESoPjZw+//FJxx25me8+HA7wNDPL8YgcIaDmTl2Ytc+ZZ8myesxsOSO5gMJw5OwG/FrMDOWbGkm2Hk+UkcjccMDzDkGBwm5CW82+gWuTfPDiQ2EaMlhs5xg8/th22k5bgYThwkBgt9jfemDEznDmcINmTZnCw4YwEYb9I9ucYf/xRcdhe4vjhx5//VNjI80sT0AIEbNI8DAyJDRCOBEHlIMD88QfQgUQpHQWjYBSMgpEJAN3wTiTtBmiiAAAAAElFTkSuQmCC","orcid":"","institution":"Henan Normal University","correspondingAuthor":true,"prefix":"","firstName":"Gongke","middleName":"","lastName":"Wang","suffix":""}],"badges":[],"createdAt":"2026-03-03 13:55:56","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9021008/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9021008/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00604-026-08085-5","type":"published","date":"2026-04-23T15:59:31+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":104520211,"identity":"a29f275b-9d58-40a1-9df0-d3923b52b3c6","added_by":"auto","created_at":"2026-03-12 19:20:07","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":152823,"visible":true,"origin":"","legend":"\u003cp\u003e(a) TEM image of CsPbBr₃@SDS QDs, with an inset showing the lattice spacing and corresponding crystal plane of CsPbBr₃@SDS QDs; (b) size distribution of CsPbBr₃@SDS QDs; (c) XRD pattern of CsPbBr₃@SDS QDs and its corresponding PDF plot; (d) FTIR spectrum of CsPbBr₃@SDS QDs; (e) XPS O 1s spectra of CsPbBr₃@SDS QDs and CsPbBr₃ QDs.\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9021008/v1/930b0dd9fbc80c73c0c0e462.jpg"},{"id":104520216,"identity":"9da8682a-4594-48b5-9642-eb59c3a92a70","added_by":"auto","created_at":"2026-03-12 19:20:07","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":104796,"visible":true,"origin":"","legend":"\u003cp\u003e(a) TEM image of CsPbBr₃@SDS QDs, with an inset showing the lattice spacing and corresponding crystal plane of CsPbBr₃@SDS QDs; (b) size distribution of CsPbBr₃@SDS QDs; (c) XRD pattern of CsPbBr₃@SDS QDs and its corresponding PDF plot; (d) FTIR spectrum of CsPbBr₃@SDS QDs; (e) XPS O 1s spectra of CsPbBr₃@SDS QDs and CsPbBr₃ QDs.\u003c/p\u003e","description":"","filename":"Picture2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9021008/v1/9079c12943cd1a431c20007e.jpg"},{"id":104520214,"identity":"3223308c-8a2d-42e2-97b6-8a309889f749","added_by":"auto","created_at":"2026-03-12 19:20:07","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":136868,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Fluorescence excitation and emission spectra of CsPbBr₃@BBA QDs, and absorption spectrum of TNB; (b) Fluorescence spectra of CsPbBr₃@BBA QDs and CsPbBr₃@BBA QDs incubated with Cys, DTNB, and mixtures of Cys and DTNB. Inset: fluorescence images of the CsPbBr₃@BBA QDs/DTNB mixture before and after incubation with Cys; (c) Fluorescence lifetimes of CsPbBr₃@BBA QDs, CsPbBr₃@BBA QDs/DTNB, and CsPbBr₃@BBA QDs/DTNB/Cys; (d) Zeta potential profiles of composite materials: CsPbBr₃@BBA QDs, CsPbBr₃@BBA QDs/DTNB, Cys/DTNB, and CsPbBr₃@BBA QDs/Cys/DTNB.\u003c/p\u003e","description":"","filename":"Picture3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9021008/v1/7bcf5a09dcc5d4b979fe639d.jpg"},{"id":104520212,"identity":"fe5720d6-766e-4907-8a76-af55ddf20bba","added_by":"auto","created_at":"2026-03-12 19:20:07","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":146721,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Fluorescence emission spectra of CsPbBr₃@SDS QDs in the presence of different concentrations of Cys (0–100 μM); (b) Changes in the fluorescence intensity of CsPbBr₃@SDS QDs mixed with DTNB after incubation with different Cys concentrations; inset: linear region of the curve; (c) UV–Vis spectra of CsPbBr₃@SDS QDs/DTNB in the presence of different Cys concentrations (0–100 μM); (d) Absorbance at 412 nm of CsPbBr₃@SDS QDs/DTNB incubated with different Cys concentrations; inset: linear region of the curve.\u003c/p\u003e","description":"","filename":"Picture4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9021008/v1/009e2d77b65384980ee47d93.jpg"},{"id":104520219,"identity":"94d3c294-c5ce-4a27-8996-6a9a7093b885","added_by":"auto","created_at":"2026-03-12 19:20:07","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":147640,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Fluorescence emission spectra of CsPbBr₃@SDS QDs in the presence of different GSH concentrations (0–100 μM); (b) Changes in the fluorescence intensity of CsPbBr₃@SDS QDs mixed with DTNB after incubation with different GSH concentrations; inset: linear region of the curve; (c) UV–Vis spectra of CsPbBr₃@SDS QDs/DTNB in the presence of GSH at different concentrations (0–100 μM); (d) Changes in absorbance at 412 nm of CsPbBr₃@SDS QDs/DTNB incubated with different concentrations of GSH; inset: linear region of the curve.\u003c/p\u003e","description":"","filename":"Picture5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9021008/v1/b79c8b62e387254ab9fb4ed0.jpg"},{"id":104520213,"identity":"0ce522c3-9a0c-4fd2-8c6b-70df539de722","added_by":"auto","created_at":"2026-03-12 19:20:07","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":138550,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Fluorescence emission spectra of CsPbBr₃@SDS QDs in the presence of different Hcy concentrations (0–100 μM); (b) Changes in the fluorescence intensity of CsPbBr₃@SDS QDs mixed with DTNB after incubation with different Hcy concentrations; inset: linear region of the curve; (c) UV–Vis spectra of CsPbBr₃@SDS QDs/DTNB in the presence of different Hcy concentrations (0–100 μM); (d) Changes in absorbance at 412 nm of CsPbBr₃@SDS QDs/DTNB incubated with different Hcy concentrations; inset: linear region of the curve.\u003c/p\u003e","description":"","filename":"Picture6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9021008/v1/06b1207438a648af307fa89e.jpg"},{"id":104780775,"identity":"199a9ff6-34ff-49ae-b953-873eb8bee444","added_by":"auto","created_at":"2026-03-17 07:53:54","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":160650,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Corresponding fluorescence changes of the CsPbBr₃@SDS QDs/DTNB mixture toward various analytes; (b) Corresponding fluorescence changes of the CsPbBr₃@SDS QDs/DTNB mixture for various analytes after adding the biothiols target (40 μM); (c) Photographs of the CsPbBr₃@SDS QDs/DTNB mixture and various analytes under UV light at 365 nm.\u003c/p\u003e","description":"","filename":"Picture7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9021008/v1/5950bdbe69b7c132f0589913.jpg"},{"id":107928568,"identity":"55d94c6f-319e-43aa-b43a-8ce874b60e41","added_by":"auto","created_at":"2026-04-27 16:11:21","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1238126,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9021008/v1/764db935-7b48-43d5-8698-bd9a7c1b4184.pdf"},{"id":104520218,"identity":"538e7bca-bc30-4845-ba94-8c14733f7597","added_by":"auto","created_at":"2026-03-12 19:20:07","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":240025,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementary.docx","url":"https://assets-eu.researchsquare.com/files/rs-9021008/v1/8519587f1bbc6422324bd8d3.docx"},{"id":104520217,"identity":"42b4f1bc-0f40-415d-bac8-60763e5c4c17","added_by":"auto","created_at":"2026-03-12 19:20:07","extension":"png","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":1092036,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme 1.\u003c/strong\u003e Schematic illustration of the synthesis of CsPbBr₃@SDS QDs and the dual-mode detection mechanism of the biothiol sensing system.\u003c/p\u003e","description":"","filename":"graphicalabstract.png","url":"https://assets-eu.researchsquare.com/files/rs-9021008/v1/b418c3c6f9a7584b4f119512.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"Toward High-Performance Biosensing: Dual-Mode Detection of Biological Thiols via Synergistic Passivation of Perovskite Quantum Dots","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eBbiothiols constitute a class of crucial biological small-molecule antioxidants. They play vital supporting roles in numerous physiological processes and serve as indispensable components for ensuring normal biological functions and maintaining human health. These compounds are abundantly present in biological cells, wheat germ, and yeast [1\u0026ndash;4]. Biothiols serve as key scavengers for reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂) and lipid peroxides, functioning as essential components within various antioxidant enzymes. They play crucial roles in cellular damage repair, the maintenance of vascular health, and the preservation of protein functional homeostasis [5,6]. The human body relies on exogenous precursors to synthesize biothiols, and these precursors must be obtained through dietary intake. Therefore, a balanced diet is crucial for maintaining good health. Abnormal biothiols concentrations can trigger various diseases. For example, Cys deficiency can lead to skin damage, lethargy, and reduced body fat [7], while elevated Hcy levels are associated with cardiovascular and Alzheimer's diseases. Imbalances in GSH levels may influence the development of cancer, aging, and heart diseases [8].\u003c/p\u003e \u003cp\u003eCurrently, the primary methods for detecting biothiols include hydrophilic interaction chromatography coupled with electrospray tandem mass spectrometry (HILIC-MS/MS) [9], electrospray ionization tandem mass spectrometry (ESI-MS/MS) [10,11], and high-performance liquid chromatography (HPLC) [12,13]. Although these methods offer high precision and sensitivity, their complex operation, long processing times, and cumbersome sample preparation procedures limit their application in field testing. Additionally, 5,5'-dithiobis (2-nitrobenzoic acid) (DTNB) is employed for the colorimetric sensing of biothiols because of its specific recognition of \u0026ndash;SH [14, 15], as demonstrated in the DTNB-gold nanoparticle (DTNB\u0026ndash;AuNP) colorimetric sensor developed by Mustafa et al [14]. However, the aggregation of AuNPs in complex biological samples can lead to false positives, and their limited sensitivity hinders their practical application. Therefore, a convenient, highly accurate, and selective detection method for biothiols is urgently needed. All-inorganic perovskite quantum dots (CsPbX₃ QDs) serve as ideal fluorescent probes for the detection of biological thiols, owing to their high sensitivity, cost-effectiveness, strong selectivity, ease of operation, and non-destructive nature.\u003c/p\u003e \u003cp\u003eHowever, CsPbX₃ QDs exhibit poor stability in polar media, particularly aqueous solutions, which limits their applications [16]. Although strategies such as the water emulsion method, ligand reconfiguration, and recrystallization have been employed to enhance their water solubility, challenges remain, including complex operations, the use of toxic reagents, and colloidal instability [17]. Therefore, exploring simple, green, and stable CsPbX3 QD-based sensing technologies remains a key focus of current research.\u003c/p\u003e \u003cp\u003eTo address these challenges, we designed a multi-ligand passivation strategy. In this study, multifunctional ligands were used to synergistically passivate CsPbX3. The introduction of 4-bromobutyric acid (BBA), oleylamine (OLA), and sodium dodecyl sulfate (SDS) ligands formed an external hydrophobic protective shell on the surface of the CsPbBr₃ QDs. This effectively inhibits the intrusion of water molecules and enhances their resistance to decomposition in aqueous environments, enabling stable emissions for up to 120 h. Therefore, a fluorescent sensor based on the CsPbBr₃@SDS QDs and DTNB composite system was constructed, as shown in Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. CsPbBr₃@SDS QDs emit green light at 520 nm when excited at 365 nm, forming a stable fluorescent system upon complexation with DTNB. Leveraging the selective recognition of thiol groups by DTNB, biothiols induce fluorescence quenching in CsPbBr₃@SDS QDs via an inner-filter effect (IFE), accompanied by a color shift from light green to yellow in solution. This enables the dual-mode fluorescence\u0026ndash;colorimetric detection of biothiols. The fluorescent sensor developed by our research institute exhibiteds high sensitivity and strong anti-interference capabilities. GSH, Cys, and HCy were successfully detected in biological samples (such as human blood serum), offering a promising exploratory approach for the application of CsPbX₃ QDs in the field of life sciences and health.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Materials and reagents\u003c/h2\u003e \u003cp\u003eChemical reagents were procured from two primary suppliers. Aladdin Biochemical Technology Co., Ltd. (Shanghai, China) provided the synthesis materials: lead bromide (PbBr₂, 98%), cesium bromide (CsBr, 99%), oleylamine (OLA, 90%), oleic acid (OA), 1-octadecene (ODE), as well as ligands and modifiers including sodium dodecyl sulfate (SDS), 4-bromobutyric acid (BBA), and (3-aminopropyl) trimethoxysilane (3-APTMS), alongside solvents (DMA, DMF) and hydrochloric acid (HCl). Glutathione, cysteine, homocysteine, and related amino acids were obtained from Macklin (Shanghai, China). All chemicals were utilized directly without additional purification steps.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Characterization\u003c/h2\u003e \u003cp\u003eThe crystalline phases of the prepared samples were identified using a Panalytical X'Pert3 Powder X-ray diffractometer (XRD). XRD instrument employed graphite monochromatic Cu-Kα radiation (λ\u0026thinsp;=\u0026thinsp;0.15418 nm) with a scan step size of 0.02\u0026deg; and a scan range from 10\u0026deg; to 80\u0026deg;. We employed two distinct spectrophotometers for optical analyses. A Beijing Purkinje TU-1810 UV\u0026ndash;Vis spectrophotometer was used to measure sample absorption, and a Varian CARY Eclipse fluorescence spectrophotometer was utilized to acquire the steady-state photoluminescence (PL) spectra. All fluorescence spectra were recorded with the excitation and emission slit widths fixed at 5 nm. The transient fluorescence spectra were acquired using an Edinburgh Instruments FLS980 instrument. X-ray photoelectron spectroscopy (XPS) was performed using an ESCALAB 250Xi instrument (Thermo Fisher Scientific, USA). The Fourier transform infrared spectra (FT-IR) was performed using the KBr pellet technique in transmission mode over 4000\u0026ndash;500 cm⁻\u0026sup1; with a Bio-Rad (USA) instrument. Infrared spectra were obtained using a Bruker FTS-40 instrument. A JEM-2100 transmission electron microscope (JEOL, Tokyo, Japan) was employed for obtaining TEM images of the samples. The nanoparticle size was measured using a Zetasizer Pro (Malvern PANalytical Ltd.).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Preparation of CsPbBr₃ QDs\u003c/h2\u003e \u003cp\u003eThe synthesis in this study was based on a ligand-assisted precipitation method reported in the literature, with appropriate modifications and improvements [18]. PbBr₂ (0.4 mmol) and CsBr (0.4 mmol) were successively dissolved in 10 mL of DMF in a transparent vial under constant temperature stirring for 1 h. Subsequently, OLA and BBA were sequentially injected rapidly into the above solution. The solution was then stirred under constant heating for 20 min to ensure complete reaction of the ligands. Subsequently, 2 mL of the precursor solution was added to 25 mL of the water solution. After the reaction, the mixture was centrifuged to remove the precipitate. The collected supernatant was subjected to high-speed centrifugation to obtain a clear solution. The final CsPbBr3@BBA QDs were stored at 4\u0026deg;C for future use.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Synthesis of CsPbBr₃@SDS QDs.\u003c/h2\u003e \u003cp\u003eBoth PbBr₂ (146.8 mg) and CsBr (85.1 mg) were added to a glass reaction flask containing 10 mL of DMA solution. After mixing, constant stirring was maintained at a constant temperature in a water bath for 45 min. Under vigorous stirring, OLA (0.3 mL), BBA (0.3 mL), and a DMA solution containing the SDS ligand (2 mmol) were added. Stirring until a pale-yellow emulsion was formed. Subsequently, a small amount of the prepared emulsion was injected into pure water. The precipitate was removed by centrifugation. Finally, the supernatant was stored in a refrigerator for subsequent experiments. Air recrystallization was employed throughout the entire synthetic process, and no noble gas was introduced at any stage.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5. Fluorescent detection of biothiols\u003c/h2\u003e \u003cp\u003eThe experimental procedure in which the fluorescent sensor detects biothiols is as follows: first, 300 \u0026micro;L of target analyte solutions at different concentrations (Tris-HCl buffer, 0.01 M) or blank control solution was added to the reaction system. The reaction system was prepared by combining CsPbBr₃@SDS QDs (in Tris-HCl buffer) with 100 \u0026micro;L of 1 mM DTNB. The mixed solution was thoroughly shaken and incubatd at room temperature to ensure a complete reaction.A fluorescence spectrophotometer, with an excitation wavelength set at 365 nm, was employed to record the emission spectra of all samples, and both the excitation and emission slit widths were set to 5 nm. Simultaneously, a UV\u0026ndash;Vis spectrophotometer measured the fluorescence absorption peaks before and after the addition the target analyte.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.6. Selectivity and interference tests\u003c/h2\u003e \u003cp\u003eAnti-interference experiments were preformed to evaluate the applicability of the sensor in complex systems. The experiment selected several common amino acids (aspartic acid (Asp), histidine (His), serine (Ser), alanine (Ala), valine (Val), threonine (Thr), phenylalanine (Phe), isoleucine (Iso), and arginine (Arg)), along with inorganic ions (NO₃⁻, Cl⁻, SO₄\u0026sup2;⁻, K⁺, Na⁺, Ca\u0026sup2;⁺, Zn\u0026sup2;⁺, and Mg\u0026sup2;⁺) as potential interferents. The antioxidant vitamin C (VC) was also introduced to further investigate its effects.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.7. Disposal of real samples\u003c/h2\u003e \u003cp\u003eFluorescence and colorimetric methods employed in this study were used to detect biothiols in human blood serum samples. Healthy human blood serum samples (Solarbio Tech Co., Ltd.) were immediately frozen upon collection to maintain their stability and biological activity for experimental use. Before analysis, serum samples were diluted 1:30 with 0.01 M Tris-HCl buffer (pH\u0026thinsp;=\u0026thinsp;7.0) to minimize matrix effects on the detection results. Subsequently, add 10, 20, and 30 \u0026micro;M biothiols standard solutions to the diluted serum. The samples were analyzed using a fluorescence detection method based on the IFE to evaluate the detection performance of the sensor.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Characterization of CsPbBr3@SDS QDs\u003c/h2\u003e \u003cp\u003eAnalysis was performed using multiple characterization methods, including fluorescence spectroscopy, UV\u0026ndash;Vis spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy, the structure and optical properties of CsPbBr₃@SDS QDs were systematically investigated, confirming their successful preparation. TEM analysis (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea and \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb) indicates that the obtained CsPbBr₃@SDS QDs exhibit good dispersion and size uniformity, with an average particle size of approximately 30.68\u0026thinsp;\u0026plusmn;\u0026thinsp;3.18 nm. High-resolution TEM images clearly reveal lattice fringes with a spacing of 0.42 nm, corresponding to the [110] crystal plane of cubic CsPbBr₃ [19], indicating that aqueous-phase synthesis did not affect its intrinsic crystal structure. Furthermore, the introduction of SDS plays a crucial role in stabilizing CsPbBr₃ QDs. SDS-protected QDs (CsPbBr₃@SDS) retain excellent monodispersity and form aggregates composed of 7\u0026ndash;9 CsPbBr₃ QDs, indicating that SDS maintains the crystal structure of CsPbBr₃ QDs even after encapsulation. The long carbon chains in SDS molecules aggregate CsPbBr₃ QDs through the hydrophobic effect, while the hydrophilic sulfate ester groups face the aqueous phase, inhibiting water molecule penetration. This enhances the physicochemical stability and anti-disintegration properties of CsPbBr₃@SDS QDs. XRD (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec) further confirmed the crystal structure of CsPbBr₃@SDS QDs. Their diffraction peaks perfectly matched the cubic perovskite structure of standard CsPbBr₃ (PDF#18\u0026ndash;0364), indicating that SDS encapsulation did not alter its crystal phase. FT-IR spectroscopy (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed) detected an S\u0026thinsp;=\u0026thinsp;O stretching vibration peak at 1036 cm⁻\u0026sup1;, indicating that SDS molecules were successfully modified onto the surface of CsPbBr₃ QDs, participated in the formation of surface states, and effectively enhanced the stability of the QDs. XPS analysis further validated the surface modification effect of SDS on CsPbBr₃@SDS QDs. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ee, the O 1s signal of CsPbBr₃@SDS QDs exhibited S-O-related peaks in the high-resolution O 1s spectrum, indicating chemical bonding between SDS molecules and CsPbBr₃ QDs. Compared with unmodified CsPbBr₃ QDs, the O-C-O and C-O binding energies in CsPbBr₃@SDS QDs exhibited shifts, further demonstrating the formation of stable coordination structures on the QD surface by SDS [20, 21]. The shift in the peak positions observed in the XPS spectrum (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e) further indicates an interaction between CsPbBr₃ QDs and SDS, in agreement with the work of Zhang et al [22]. Through multiple spectroscopic and structural characterization techniques, we verified the successful surface modification of SDS on CsPbBr₃ QDs, significantly enhancing their water stability and optical properties. This strategy provides an effective approach for preparing stable and efficient QDs in aqueous solutions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Stability assessment of CsPbBr3@SDS QDs\u003c/h2\u003e \u003cp\u003eAs shown in the UV-Vis and fluorescence spectra of CsPbBr₃ and CsPbBr₃@SDS QDs (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea), CsPbBr₃ QDs exhibit weak green fluorescence emission at 521 nm upon 365 nm excitation. However, the fluorescence intensity is significantly enhanced in aqueous solution upon modification with SDS ligands, indicating that SDS markedly optimizes the optical properties of CsPbBr₃ QDs. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb, compared with the slightly turbid solution formed by CsPbBr₃ QDs, the solution formed by CsPbBr₃@SDS QDs exhibits high transparency, indicating superior dispersibility and stability in aqueous environments. Further studies revealed that even after 120 h in the water solution, CsPbBr₃@SDS QDs retained strong green fluorescence (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec), demonstrating excellent water stability. This enhanced water solubility and degradation resistance likely stems from two mechanisms: (1) the oxygen atoms in the sulfate ester group of SDS molecules form coordination bonds with Pb\u0026sup2;⁺ ions [23], effectively reducing surface vacancy defects and thereby enhancing the photostability of QDs and (2) the external hydrophobic shell formed by SDS on the CsPbBr₃ QD surface effectively inhibits water molecule intrusion, further strengthening the hydrolysis resistance of the material. The prepared CsPbBr₃@SDS QDs exhibit outstanding optical stability in aqueous environments, maintaining excellent fluorescence properties even under varying dilution conditions. Their robust resistance to degradation and environmental adaptability offer broad potential applications in aqueous detection, bioimaging, and other optical fields.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Feasibility analysis of biothiol detection and mechanism of fluorescence detection\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea shows that the excitation peak of CsPbBr₃@SDS QDs is located at 264 nm, with a fluorescence emission peak at 520 nm, while TNB exhibits a strong and broad absorption peak at 347 nm. Notably, the excitation peak of CsPbBr₃@SDS QDs overlaps to some extent with the absorption peak of TNB. The presence of Cys has a negligible impact on the fluorescence of CsPbBr₃@SDS QDs, as evidenced by their sustained strong green emission shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb. However, the addition of DTNB leads to a considerable drop in the fluorescence intensity exhibited by CsPbBr₃@SDS QDs, which may be attributed to the partial decomposition of DTNB into TNB. Further analysis revealed that when Cys was added to the CsPbBr₃@SDS QDs and DTNB mixture, \u0026ndash;SH of Cys reacted with DTNB to form yellow TNB. Owing to the strong absorption of TNB at 347 nm and its ability to absorb the excitation light at 264 nm, this reaction triggers fluorescence quenching. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed, both CsPbBr₃@SDS QDs and TNB exhibit positive charges; thus, the conditions for electrostatic adsorption are not met and TNB is unable to bind to the QD surface. This excludes the possibility of a fluorescence resonance energy transfer (FRET) mechanism. The fluorescence lifetime analysis further confirmed the fluorescence quenching mechanism of the sensor. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec, the fluorescence lifetime of CsPbBr₃@SDS QDs was 138.81 ns, and no significant decay was observed after incubation with DTNB (136.57 ns) or DTNB/Cys (135.24 ns). This phenomenon indicates that CsPbBr₃@SDS QDs primarily undergo static quenching rather than dynamic quenching during the fluorescence quenching process [24, 25]. Therefore, the fluorescence quenching can be inferred to originate primarily from IFE rather than from FRET. These results demonstrate that the prepared sensor system can effectively detect biothiols and provide reliable theoretical support for the highly sensitive detection of biothiols.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.4. Optimization of the detection system\u003c/h2\u003e \u003cp\u003eThe effects of incubation time, temperature, and Tris-HCl buffer pH on the sensitivity and stability of the fluorescent sensor were systematically investigated to optimize its performance for biothiol detection. The influence of incubation time was assessed by monitoring the fluorescence intensity at 521 nm was evaluated, as shown in Fig. S2a, 2d and 2g. with incubation times ranging from 0 to 40 min. Following the introduction of the three biothiols, a rapid and notable fluorescence response ensued. After 1 min of incubation, the fluorescence intensity decreased significantly, and the signal stabilized within 5 min, indicating that the reaction had essentially reached equilibrium. Considering both the detection efficiency and experimental precision, 5 min was ultimately determined as the optimal incubation time to meet the rapid testing requirements. Fig. S2b, 2e and 2h illustrates the detection performance of the sensor was evaluated under different Tris-HCl buffer pH conditions. Within the pH range of 3.0\u0026ndash;7.0, the fluorescence intensity gradually increased with increasing pH. Conversely, in the pH range of 7.0\u0026ndash;9.0, the fluorescence intensity progressively decreased as the pH increased. The oxidation of biothiols under high pH conditions, along with alterations in the stability of the sensing system, may both contribute to this phenomenon. Based on this, the pH of the detection system was set to 7.0 for all subsequent experiments. Fig. S2c, 2f and 2i further illustrates the effect of different ambient temperatures on the detection performance of the sensor. The experimental results indicate that the fluorescence intensity exhibits the most pronounced variation at 25\u0026deg;C (room temperature). As the temperature increases, the fluorescence intensity of the sensing system gradually decreases, and the magnitude of the fluorescence intensity change diminishes upon target addition. This may be attributed to the enhanced non-radiative transitions of QDs at elevated temperatures, leading to intensified fluorescence quenching effects and consequently reduced detection sensitivity. Therefore, room temperature (25\u0026deg;C) was determined to be the optimal detection temperature for this sensing system to ensure its sensitivity and stability in practical applications. In summary, a pH\u0026thinsp;=\u0026thinsp;7.0 aqueous environment, a 5-min incubation period, and detection at 25\u0026deg;C were established as the optimal experimental conditions for detecting biothiols. This optimization strategy not only enhances the sensitivity and stability of the sensor but also ensures its practical applicability in real-world scenarios, providing a reliable experimental foundation for further expanding its use in biomedical and environmental monitoring applications.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.5. Target detection\u003c/h2\u003e \u003cp\u003eAfter optimizing the detection conditions, the system was used to evaluate the performance of this fluorescent sensor in detecting biothiols. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea, the sensor exhibits distinct fluorescence emission peaks after incubation with different concentrations of Cys, and the fluorescence intensity gradually decreases as the Cys concentration increases. With the detection range spanning 0\u0026ndash;100 \u0026micro;M. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb further reveals a good linear relationship between the change in fluorescence intensity (ΔF) and Cys concentration, exhibiting high correlation (R\u0026sup2; = 0.997) within the range of 0.05\u0026ndash;40 \u0026micro;M ,with a detection limit of 2.63 \u0026micro;M. The linear regression equation is ΔF\u0026thinsp;=\u0026thinsp;12.92CCys\u0026thinsp;+\u0026thinsp;5.54, where ΔF represents the change in fluorescence intensity (ΔF\u0026thinsp;=\u0026thinsp;F (CsPbBr₃@SDS QDs/DTNB) \u0026ndash; F (CsPbBr₃@SDS QDs/DTNB/analyte), and C denotes the Cys concentration (\u0026micro;M). The linear detection ranges for GSH and Hcy are 0.5\u0026ndash;40 \u0026micro;M, with detection limits of 3.09 \u0026micro;M and 2.15 \u0026micro;M, respectively. This demonstrates that the sensor exhibits excellent sensitivity and stability when detecting different biothiols (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea, \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb and Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea, \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb). To further investigate the detection mechanism, the UV\u0026ndash;Vis absorption spectra of CsPbBr₃@SDS QDs/DTNB were analyzed at different Cys concentrations (0\u0026ndash;100 \u0026micro;M) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec). As the Cys concentration increases, the characteristic absorption peak at 412 nm gradually intensifies, exhibiting a good linear relationship within the range of 0\u0026ndash;40 \u0026micro;M (R\u0026sup2; = 0.996), with a detection limit of 0.92 \u0026micro;M (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed). Similarly, GSH exhibited a stable linear relationship within the range of 0\u0026ndash;40 \u0026micro;M (R\u0026sup2; = 0.991), with a detection limit of 0.74 \u0026micro;M (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec and \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ed), while Hcy also demonstrated a good linear response within 0.1\u0026ndash;40 \u0026micro;M (R\u0026sup2; = 0.991), with a detection limit of 0.82 \u0026micro;M (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ec and \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ed). These results further validate the detection mechanism of the fluorescent sensor and demonstrate its feasibility for detecting biothiols. As shown in Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e, this sensor demonstrates superior performance in terms of sensitivity and detection limit compared to previously reported sensors. This exceptional detection capability is primarily attributed to the highly efficient reaction mechanism between the biothiols and DTNB. Furthermore, the optimized detection procedure and simplified operational steps further enhance its feasibility and stability in practical applications. Overall, this fluorescent sensor not only exhibits high sensitivity, rapid response, and excellent selectivity but also demonstrates significant advantages in detection reliability and application scalability, providing a flexible and efficient solution for the effective detection of biothiols.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.6. Selective interference studies\u003c/h2\u003e \u003cp\u003eThis study employed a fluorescence detection method to measure multiple common amino acids (aspartic acid (Asp), histidine (His), serine (Ser), alanine (Ala), valine (Val), threonine (Thr), phenylalanine (Phe), isoleucine (Iso), and arginine (Arg)), as well as inorganic ions (NO₃⁻, Cl⁻, SO₄\u0026sup2;⁻, K⁺, Na⁺, Ca\u0026sup2;⁺, Zn\u0026sup2;⁺, and Mg\u0026sup2;⁺). After incubating the CsPbBr₃@SDS QDs sensing system with different analytes for 5 min, the changes in the fluorescence intensity at 521 nm were measured. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea, Cys, GSH, and Hcy (40 \u0026micro;M) all significantly induce fluorescence quenching, while other potential interferents do not cause noticeable fluorescence changes even at higher concentrations (2 mM). This phenomenon is primarily attributed to the specific interaction between \u0026ndash;SH in biothiols and DTNB, whereas other coexisting substances cannot participate in this reaction and thus do not affect the fluorescence signal. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb demonstrates that the presence of biothiols does not affect the corresponding fluorescence changes of the CsPbBr₃@SDS QDs and DTNB mixture toward various analytes. This sensor exhibits exceptional selectivity toward biothiols and possesses outstanding interference resistance, providing reliable assurance for highly sensitive detection in complex biological systems.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e3.7. Analysis of real samples\u003c/h2\u003e \u003cp\u003eExperimental results indicated excellent selectivity of the CsPbBr₃@SDS QDs and DTNB-based fluorescence sensor toward biothiols.To evaluate the detection performance and applicability of the sensor in complex biological samples, authentic human blood serum samples were tested. A fluorescence-based detection method utilizing IFE to quantitatively analyze the biothiol content was employed. To further validate the applicability of the sensor for complex biological samples, experiments were conducted using fluorescence and colorimetric methods to detect human blood serum samples spiked with various concentrations of Cys, GSH, and Hcy. The results are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The detection method demonstrated high accuracy and stability, evidenced by sample recovery rates close to 100% and excellent reproducibility. Together, these data establish both the feasibility of biothiol analysis with the prepared fluorescent sensor and its capability for dual-mode detection.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDetection of Biothiols in Human Blood Serum Samples (n\u0026thinsp;=\u0026thinsp;3, Fluorescence Method)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAdded(\u0026micro;M)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFound(\u0026micro;M)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRecovery(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRSD(%, n\u0026thinsp;=\u0026thinsp;3)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eCys\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e10.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.22\u0026ndash;107.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.47\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e20.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e101.69\u0026ndash;105.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.74\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e29.49\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e97.84\u0026ndash;98.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eGSH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e10.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e96.91\u0026ndash;105.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e19.88\u0026thinsp;\u0026plusmn;\u0026thinsp;0.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e96.02\u0026ndash;102.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.70\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e30.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e101.28\u0026ndash;103.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e2.71\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eHcy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e9.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e93.93\u0026ndash;105.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.68\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e20.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.24\u0026ndash;102.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.31\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e29.93\u0026thinsp;\u0026plusmn;\u0026thinsp;0.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e97.36\u0026ndash;102.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4.79\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDetection of Biothiols in Human Blood Serum Samples (n\u0026thinsp;=\u0026thinsp;3, Colorimetric Method)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAdded(\u0026micro;M)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFound(\u0026micro;M)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRecovery(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRSD(%, n\u0026thinsp;=\u0026thinsp;3)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eCys\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1047\u0026thinsp;\u0026plusmn;\u0026thinsp;0.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e98.19\u0026ndash;111.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.61\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e20.42\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100.25\u0026ndash;103.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.75\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e29.95\u0026thinsp;\u0026plusmn;\u0026thinsp;1.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e96.08\u0026ndash;103.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.88\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eGSH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e10.03\u0026thinsp;\u0026plusmn;\u0026thinsp;0.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e96.6\u0026ndash;104.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e19.77\u0026thinsp;\u0026plusmn;\u0026thinsp;0.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e97.00\u0026ndash;100.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.77\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e31.03\u0026thinsp;\u0026plusmn;\u0026thinsp;0.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e102.18\u0026ndash;104.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.62\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eHcy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e9.82\u0026thinsp;\u0026plusmn;\u0026thinsp;0.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e94.43\u0026ndash;101.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.64\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e20.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e97.79\u0026ndash;104.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e29.93\u0026thinsp;\u0026plusmn;\u0026thinsp;0.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e99.83\u0026ndash;104.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.08\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThis study proposes a surface confinement strategy that effectively suppresses QD disintegration by encapsulating CsPbBr₃ QDs with SDS in an aqueous medium. The long flexible carbon chains of SDS form hydrophobic association structures around the QD, thereby constructing a stable hydrophobic encapsulation shell that effectively passivates surface defects and optimizes their local environment. Furthermore, the sulfate groups in SDS molecules further promote the modification of surface defects by forming coordination bonds with Pb\u0026sup2;⁺ ions. This strategy significantly enhances the water stability of CsPbBr₃@SDS QDs while preserving their outstanding optical properties and high fluorescence quantum yield. We have successfully developed a bio-mercury-responsive fluorescent sensor based on the CsPbBr₃@SDS QDs and DTNB system, providing a novel research direction for the analytical application of perovskite nanocrystals in aqueous environments. The high sensitivity and selectivity of this sensor primarily stem from the specific reaction between \u0026ndash;SH in the biothiols and DTNB. Capable of dual-mode detection via both fluorescence and colorimetric methods, the sensor demonstrates excellent repeatability, stability, and resistance to interference. This work established an effective strategy for the efficient detection of biothiols using the developed fluorescence-based sensor, with potential applications in fields such as bioanalysis, medical diagnostics, and environmental monitoring.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eDeclaration of Competing Interest\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eConflicts of Interest\u003c/h2\u003e \u003cp\u003eThe authors declare no conflict interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work was financially supported by the National Natural Science Foundation of China (No. 22573028) and Natural Science Foundation of Henan Province (No. 252300420250).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003e**Songbing Gao** : Investigation, Writing-original draft, Data analysis. **Qianfeng Li** : Investigation, Software, Data curation. **Haifa Zhai** : Project administration, Validation, Formal analysis. **Gongke Wang** : Conceptualization, Methodology, Supervision, Writing\u0026ndash;review \u0026amp;amp; editing, Resources, Funding acquisition.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eData will be made available on request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eZu Y (2009) Molecular and nanoparticle postcolumn reagents for assay of low-molecular-mass biothiols using high-performance liquid chromatography. J Chromatogr B 877:3358–3365. https://doi.org/10.1016/j.jchromb.2009.04.031\u003c/li\u003e\n\u003cli\u003eIsokawa M, Kanamori T, Funatsu T, Tsunoda M (2014) Analytical methods involving separation techniques for determination of low-molecular-weight biothiols in human plasma and blood. J Chromatogr B 964:103–115. https://doi.org/10.1016/j.jchromb.2013.12.041\u003c/li\u003e\n\u003cli\u003eLabib M, Sargent EH, Kelley SO (2016) Electrochemical methods for the analysis of clinically relevant biomolecules. Chem Rev 116:9001–9090. https://doi.org/10.1021/acs.chemrev.6b00220\u003c/li\u003e\n\u003cli\u003eHe L, Yang X, Xu K, Lin W (2017) Improved Aromatic Substitution–Rearrangement-Based Ratiometric Fluorescent Cysteine-Specific Probe and Its Application of Real-Time Imaging under Oxidative Stress in Living Zebrafish. Anal Chem 89:9567–9573. https://doi.org/10.1021/acs.analchem.7b02649\u003c/li\u003e\n\u003cli\u003eUlrich K, Jakob U (2019) The role of thiols in antioxidant systems. Free Radic Biol Med 140:14–27. https://doi.org/10.1016/j.freeradbiomed.2019.05.035\u003c/li\u003e\n\u003cli\u003eShi S, Shen R, Mi L, et al (2025) A red fluorescent probe with new recognition site for tracking the fluctuation of biothiol in drug-induced liver injury model. Anal Chim Acta 1369:344364. https://doi.org/10.1016/j.aca.2025.344364\u003c/li\u003e\n\u003cli\u003eSharifi E, Salimi A, Shams E (2012) DNA/nickel oxide nanoparticles/osmium(III)-complex modified electrode toward selective oxidation of l-cysteine and simultaneous detection of l-cysteine and homocysteine. Bioelectrochemistry 86:9–21. https://doi.org/10.1016/j.bioelechem.2011.12.013\u003c/li\u003e\n\u003cli\u003eGupta A, Verma NC, Khan S, Nandi CK (2016) Carbon dots for naked eye colorimetric ultrasensitive arsenic and glutathione detection. 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Sens Actuators B Chem 255:3179–3186. https://doi.org/10.1016/j.snb.2017.09.143\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":"microchimica-acta","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"miac","sideBox":"Learn more about [Microchimica Acta](https://link.springer.com/journal/604)","snPcode":"604","submissionUrl":"https://submission.springernature.com/new-submission/604/3","title":"Microchimica Acta","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Co-passivated perovskite quantum dots, Dual-mode sensing, Biological thiols, Water stability","lastPublishedDoi":"10.21203/rs.3.rs-9021008/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9021008/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eBiological thiols (biothiols), such as cysteine (Cys), glutathione (GSH), and homocysteine (Hcy) are essential for maintaining life activities, and their abnormal concentrations are closely associated with various diseases. To overcome the drawbacks of existing detection methods, we developed a dual-mode sensor using synergistically passivated CsPbBr₃ quantum dots (QDs). By introducing the ligand sodium dodecyl sulfate (SDS) into CsPbBr₃ (QDs) and combining the specific recognition ability of 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) toward thiol groups (\u0026ndash;SH), a dual-mode detection system was constructed. In the presence of biological thiols, their \u0026ndash;SH react with DTNB to generate 2-nitro-5-thiobenzoic acid (TNB). A discernible color change of the solution from light green to yellow, along with fluorescence quenching of the CsPbBr₃@SDS QDs, was observed. This is attributed to the inner-filter effect (IFE), which is initiated by the overlap of the TNB absorption spectrum with the excitation spectrum of the QDs. This enables the dual-mode detection of target analytes via fluorescence and colorimetric signals. The sensor demonstrates high sensitivity toward Cys, GSH, and Hcy, with detection limits as low as 2.63 \u0026micro;M, 3.09 \u0026micro;M, and 2.15 \u0026micro;M, respectively, along with a wide linear range. The sensor also exhibits excellent selectivity and anti-interference capabilities. This work provides an effective strategy for biothiol detection, showing promising application prospects in biomedical diagnosis and environmental monitoring.\u003c/p\u003e","manuscriptTitle":"Toward High-Performance Biosensing: Dual-Mode Detection of Biological Thiols via Synergistic Passivation of Perovskite Quantum Dots","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-12 19:20:01","doi":"10.21203/rs.3.rs-9021008/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-01T18:05:26+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-01T14:10:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"28463032375582798881234599412575786244","date":"2026-03-17T14:31:25+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-11T14:34:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"314823061950801590303658749512667955335","date":"2026-03-09T22:15:40+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-09T21:15:04+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-05T23:29:18+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-05T23:28:19+00:00","index":"","fulltext":""},{"type":"submitted","content":"Microchimica Acta","date":"2026-03-03T13:50:02+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"microchimica-acta","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"miac","sideBox":"Learn more about [Microchimica Acta](https://link.springer.com/journal/604)","snPcode":"604","submissionUrl":"https://submission.springernature.com/new-submission/604/3","title":"Microchimica Acta","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"d232df45-22c4-436b-b990-ba2feb8ae6c3","owner":[],"postedDate":"March 12th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-04-27T16:09:21+00:00","versionOfRecord":{"articleIdentity":"rs-9021008","link":"https://doi.org/10.1007/s00604-026-08085-5","journal":{"identity":"microchimica-acta","isVorOnly":false,"title":"Microchimica Acta"},"publishedOn":"2026-04-23 15:59:31","publishedOnDateReadable":"April 23rd, 2026"},"versionCreatedAt":"2026-03-12 19:20:01","video":"","vorDoi":"10.1007/s00604-026-08085-5","vorDoiUrl":"https://doi.org/10.1007/s00604-026-08085-5","workflowStages":[]},"version":"v1","identity":"rs-9021008","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9021008","identity":"rs-9021008","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}