Dissolved Bubble Microneedle Patches for Co-Delivery of Hydrophobic and Hydrophilic Drugs to Improve Acne Vulgaris Therapy

Dissolved Bubble Microneedle Patches for Co-Delivery of Hydrophobic and Hydrophilic Drugs to Improve Acne Vulgaris Therapy | 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 Article Dissolved Bubble Microneedle Patches for Co-Delivery of Hydrophobic and Hydrophilic Drugs to Improve Acne Vulgaris Therapy Can Yang Zhang, Xiaopeng Zhang, Xiaotong Zhao, Yiting Li, Wanyue Zhang, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7269052/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 24 Nov, 2025 Read the published version in Microsystems & Nanoengineering → Version 1 posted 11 You are reading this latest preprint version Abstract Acne vulgaris, a prevalent inflammatory skin disorder, poses significant clinical challenges due to its multifactorial pathogenesis involving P. acnes proliferation and chronic inflammation. Conventional therapies, including topical applications, oral medication, and laser treatments, face limitations in drug penetration, patient compliance, and therapy efficacy. Currently, the combined use of hydrophilic drugs and hydrophobic drugs is a commonly recommended clinical approach. However, conventional formulations struggle to effectively deliver and release both therapeutic agents synergistically at the affected site. To address these issues, we developed a kind of dissolved bubble microneedle patches (DBMNPs) for the co-delivery of hydrophilic (dipotassium glycyrrhizinate, DPG), hydrophobic (PIONIN) drugs, and alongside salicylic acid (SA) in a base layer. The DBMNPs, fabricated based on hyaluronic acid (HA), feature hollow bubble structures to encapsulate lipophilic agents, enabling spatially segregated and temporally controlled drug release. The patches exhibit good mechanical strength, excellent biocompatibility, and potent antimicrobial activity against P. acnes . In vivo studies confirmed their efficacy in treating acne vulgaris, offering a minimally invasive and clinically translatable approach to enhance therapeutic effect while minimizing systemic side effects. This study developed a MN platform that successfully addresses the key challenge of co-loading and co-delivering both hydrophilic and hydrophobic drugs, and are expected to be applied in the treatment of other diseases. Physical sciences/Engineering Physical sciences/Materials science Dissolved microneedle Bubble structure Drug delivery Acne vulgaris therapy Antimicrobial activity Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Acne vulgaris, a common dermatological condition, is characterized by chronic inflammation of the pilosebaceous unit 1 . It is particularly prevalent among adolescents and imposes a significant clinical burden globally, manifesting as erythematous papules, pustules, and other lesions 2 , 3 . Notably, acne vulgaris frequently results in long-term consequences, such as permanent scarring and psychological distress, which can severely affect patients’ appearance, mental health, and overall quality of life. 4 , 5 . The pathogenesis of acne vulgaris is multifactorial, involving excessive sebum production and proliferation of Propionibacterium acnes ( P. acnes ) 6 – 8 . Consequently, effective acne vulgaris management necessitates a multiple therapeutic approach combining localized antibacterial and anti-inflammatory strategies 9 , 10 . Current clinical interventions for the management of acne vulgaris include topical drug applications 11 , oral medication, and light-based therapies 12 , 13 . However, these approaches are fraught with several limitations, such as prolonged treatment durations, the emergence of antibiotic resistance, intolerable adverse effects, and poor patient compliance 14 . Namely, topical applications are obstructed by the stratum corneum barrier, drugs with a molecular weight exceeding 500 Daltons typically exhibit limited absorption 15 . As for oral medications, such as salicylic acid (SA), usually cause side effects including gastrointestinal reactions, liver and kidney damage 16 . Laser therapies can target sebaceous glands or bacterial populations but require multiple sessions. Their effectiveness for percutaneous varies across different skin types, and may cause transient erythema or hyperpigmentation 17 . Recently, the combined use of hydrophilic drugs and hydrophobic drugs is a commonly recommended clinical approach 18 . Notably, certain agents, such as Quaternium-73 (PIONIN), which exhibit superior safety and good antibacterial properties, are regarded as highly promising components for the treatment of acne vulgaris. However, their limited water solubility and low permeability substantially impede their commercial applicability 19 . Collectively, these challenges highlight the urgent need for drug delivery platforms that combine minimally invasive administration and enhanced drug penetration, especially for hydrophobic agents. Microneedles (MNs), a type of micrometer-sized needles typically less than 1000 µm in length, can penetrate the stratum corneum and deliver drugs directly into the dermis 20 , 21 . It enables efficient deliver both small molecules and macromolecules, offering a painless, minimally invasive, and high effective transdermal drug delivery strategy 22 . Additionally, MNs can achieve localized drug accumulation in deep lesion sites while avoiding systemic toxicity. Clinical trials have demonstrated that MN technology is well tolerated, easily usable and strongly accepted 23 , 24 . There are several types of MNs including solid MNs 25 , coated MNs 26 , dissolving MNs (DMNs) 27 , and swelling MNs 28 . Among them, DMNs are regarded as one of the most promising delivery platforms for clinical transformation due to their advantages such as good biocompatibility of materials, degradability, low risk of cross-infection, and flexible drug delivery 29 , 30 . Multiple studies have demonstrated the significant efficacy of DMNs in delivering antimicrobial peptides, anti-inflammatory molecules, or other agents in acne vulgaris treatment 31 , 32 . However, the matrix materials of DMNs are typically composed of water-soluble polymers such as polyvinyl alcohol (PVA) and hyaluronic acid (HA), inherently limiting the incorporation and stability of lipophilic agents and restricting their broader application in acne vulgaris therapy 33 , 34 . Therefore, enhancing the drug loading and co-delivery of hydrophilic and hydrophobic drugs remain key challenges for DMNs. Given these limitations and objectives, we designed and fabricated a dissolved bubble microneedle patches (DBMNPs) for the co-delivery of both hydrophilic and hydrophobic drugs to improve acne vulgaris therapy. Briefly, the DBMNPs were fabricated using hyaluronic acid (HA), with hollow bubble structures embedded within the MNs to encapsulate hydrophobic drugs (Fig. 1 ). The entire manufacturing process of DBMNPs is rapid and cost-effective. The patches facilitate the spatial segregation and temporally controlled release of three distinct therapeutics, including hydrophilic dipotassium glycyrrhizinate (DPG) loaded in the main body, hydrophobic PIONIN loaded in the bubbles, and salicylic acid (SA) loaded in the base layer. The prepared co-loaded DBMNPs showed high mechanical strength, good biocompatibility, and high antimicrobial properties against P. acnes. Moreover, animal studies demonstrated that the DBMNPs patches are highly effective in treating acne vulgaris. Results Fabrication and Characterization of DBMNPs The HA-based hydrophobic-hydrophilic drugs co-loaded DBMNPs are successfully fabricated via PDMS molds using micro-casting film-forming method (Fig. 2 a). The structure of the drugs co-loaded DBMNPs (10 × 10 array) are confirmed using scanning electron microscope (SEM, Fig. 2 b) and optical microscope (Fig. 2 c). Bubbles embedded in the DBMNPs are uniformly distributed within the MNs, with an average diameter of approximately 176 am and wall thickness of about 10 am (Fig. 2 b). The average height of MN is confirmed to be 500–550 mm, with a bottom diameter of approximately 300 my (Fig. 2 c). The tips of the MNs are sharp enough, making it easy to pierce into the skin. To further visually characterize the spatial distribution of the three drugs in the DBMNPs, a fluorescence labeling strategy and confocal laser scanning microscopy (CLSM) are utilized. Specifically, sulfonyl rhodamine B (SRB) is used to simulate hydrophilic DPG distribution in the main body of the MNs, FITC is used to simulate hydrophobic PIONIN distribution in the bubbles, and Cy5 is used to simulate SA distribution in the base layer. In detail, Z-stack scanning is performed along the axial direction of the MNs from the tip to the base, with a total scanning depth of 550 µm and an interlayer resolution of 50 µm. The 3D reconstruction results demonstrate that three drugs exhibit specific distributions within the MNs, as shown in Fig. 2 d. Namely, hydrophilic drug DPG was specifically localized at main body of the MNs (from Z = 0 µm to 500 µm), hydrophobic drug PIONIN is selectively distributed in the bubble region (from Z = 300 µm to 450 µm), and the hydrophilic drug SA is observed in the base layer (from Z = 400 µm to 500 µm). This drug distribution pattern highly aligned with the structural features of the MN designed in the earlier stage, confirming that the bubble MNs enable spatially controlled drug loading (Fig. 2 e). Summarily, the designed hydrophobic and hydrophilic drugs co-loaded DBMNPs were successfully fabricated based on HA matrix using micro-casting film-forming method and the three drugs are specifically loaded in the main body, bubbles, and base parts of the MNs for precise transdermal delivery. Moreover, the concentration of each drug for fabrication of DBMNPs were optimized based on their proximity to the minimum effective threshold required for complete inhibition of P. acnes , with 1% DPG, 1% SA, and 0.002% PIONIN demonstrating potent bactericidal properties (Fig. S1 ). Mechanical performance of DBMNPs Given the critical role of mechanical properties in effective transdermal delivery, the mechanical property of individual DBMNs was rigorously evaluated. Single-needle compression testing was performed using a microparticle strength tester (Fig. S2). Randomly select 50 MNs from the drug co-loaded DBMNPs to test the single-needle mechanical property. The force-displacement curves of DBMNPs clearly indicate that the force increased with the increase of displacement, and only the tip of the MN bends without breaking after compression test (Fig. 3 a). The average rupture force and Young’s modulus of single MN is 4.7 ± 0.9 MPa (Fig. 3 b) and 144.8 ± 44.8 MPa (Fig. 3 c), respectively. These results substantially surpass the reported minimum force required for MNs insertion into human skin 35 . Furthermore, insertion capability of the drugs co-loaded DBMNPs were assessed using porcine cadaver skin model. The results demonstrated that the DBMNPs consistently achieved an average insertion depth of approximately 350 µm (Fig. 3 d), confirming the existence of bubbles does not impair the penetration ability of MNs. Drug release of DBMNPs in vitro The dissolution property of DBMNPs were evaluated based on the pig cadaver skin. The MNs arranged on the DBMNPs initially maintained their structural integrity at 0 s, featuring sharp tips and uniformly distributed bubble cavities, and almost completely dissolved at 120 s (Fig. 4 a-b), which is particularly advantageous for patient compliance while ensuring prompt drug delivery. The drug release profiles of three therapeutic agents from DBMNPs were evaluated using the dialysis-bag method. The drug concentration was calculated based on a pre-validated standard curve (Fig. S3). The release results as illustrated in Fig. 4 c, an initial burst release was observed for SA, with over 50% of the payload released within the first 30 min (Fig. 4 c, inset) and the cumulative release amount reached approximately 95% at 6 h. As for DPG, localized at the main body of the DBMNPs, exhibited near-zero-order release kinetics during the initial 4 h, and approximately 70% was released at 6 h. In contrast, PIONIN, loaded within the bubble cavities, demonstrated significantly slower release due to its limited aqueous solubility, achieving about 50% cumulative release at the 6 h. The results indicated the DBMNPs enable the release of encapsulated therapeutics after application, ensuring substantial local drug availability at the target site. Biocompatibility and Antibacterial performance of DBMNPs in vitro The biocompatibility of DBMNPs was evaluated in 3T3 cells via CCK-8 assay. The results indicated that cell viability of remained above 80% across a broad concentration range (25–800 µg/mL), demonstrating good biocompatibility of the DBMNPs (Fig. 4 d). The antibacterial performance of three drugs co-loaded DBMNPs (D/P/S DBMNPs) was evaluated through agar plate assays. As shown in Fig. 4 e, both D/P/S DBMNPs and D/P/S solution group exhibited comparable antimicrobial efficacy against P. acnes , inducing severe morphological damage to bacterial cells such as membrane collapse and cytoplasmic leakage. In contrast, blank DBMNPs group showed limited antibacterial activity, as evidenced by incomplete colony reduction on agar plates and a small portion of the bacterial morphology ruptured in SEM images (Fig. 4 e). Quantitative assessment of antibacterial rates (Fig. 4 f) further confirmed the superior antimicrobial performance of three drugs co-loaded DBMNPs. These results collectively demonstrated that the antimicrobial mechanism of D/P/S DBMNPs is primarily mediated by the bioactive components released from the MNs rather than passive physical interactions. Evaluation of DBMNPs for acne vulgaris therapy in vivo Infection with P. acnes is a leading cause of acne vulgaris. To evaluate the in vivo efficacy of DBMNPs loaded with three drugs, an acne vulgaris model was established by intradermally injecting P. acnes into the right ear of BALB/c mice. Briefly, the mice were divided into five groups: untreated group (Health), untreated acne model group (Model), treated with a topical drug solution group (D/P/S Solution), treated with drug-free DBMNPs group (blank DBMNPs), and treated with drug-loaded DBMNPs group (D/P/S DBMNPs). Treatments were administered once daily for three consecutive days starting from day 0. Ear thickness was measured daily, and all mice were humanely euthanized on the third day for tissue collection (Fig. 5 a). It can be seen that the DBMNP needles almost completely dissolved within 5 min of insertion into the ear skin (Fig. S4). The therapeutic results are displayed in Fig. 5 b, after 72 h P. acnes injection, the right ears of all mice exhibited redness and swelling. Despite a three-day treatment, the symptoms persisted in the model group. Conversely, the redness and swelling symptoms in the groups treated with topical D/P/S solution, blank DBMNPs, and D/P/S DBMNPs showed a marked reduction, suggesting that all these groups are effective in treating acne vulgaris. Moreover, the symptoms of D/P/S DBMNPs group is superior to that of the blank DBMNPs group and D/P/S solution groups. This is because the DBMNPs effectively enhanced the transdermal absorption of three antimicrobial and anti-inflammatory agents with varying solubilities. Notably, although the D/P/S solution group was found to have the same antibacterial performance as D/P/S DBMNPs in vitro , it failed to relieve the symptoms due to insufficient transdermal penetration into the P. acnes rich pustular regions. The blank DBMNPs group demonstrated partial improvement in ear swelling, possibly attributable to the MNs create micropores, alleviating hypoxia in swollen regions and indirectly impairing the growth of anaerobic P. acnes . Simultaneously, we recorded the variations in ear thickness of mice during treatment. As shown in Fig. 5 c, after 72 h of P. acnes injection, the ear thickness of all mice increased from normal 0.2 mm to 0.6 mm or more. Mice treated with D/P/S DBMNPs exhibited a significant reduction in ear thickness over three days, indicating rapid resolution of swelling. In contrast, the model group and D/P/S Solution group showed similar increases in ear thickness, likely due to limited transdermal penetration of the topically applied solution. Next, the quantitative analysis of inflammatory cytokines demonstrated a significant reduction in pro-inflammatory IL-6 levels (Fig. 5 d) and a concurrent increase in anti-inflammatory IL-10 (Fig. 5 e) following treatment with D/P/S DBMNPs. Antimicrobial assessment via agar plate assays (Fig. S5) revealed nearly complete elimination of P. acnes colonies in the D/P/S DBMNPs treatment group. Histopathological examination (Fig. 5 f) further supported these observations, showing markedly reduced inflammatory cell infiltration and maintained epidermal integrity in D/P/S DBMNPs-treated specimens, in stark contrast to the extensive neutrophilic infiltration observed in both untreated and solution-treated control groups. Furthermore, the safety of DBMNPs were also evaluated according to body weight and skin recovery after administration. All treatment groups, including D/P/S DBMNPs, blank MNs, and D/P/S Solution, exhibited stable body weight throughout the therapy (Fig. S6). To further assess the safety of DBMNPs administration, we recorded the changes in the skin of healthy mice after the MNs were inserted into their right ears. The study found that the micropores created by the DBMNPs became virtually invisible to the naked eye within 5 min, and no abnormal symptoms such as redness or swelling occurred in the mice’s ears after the patch removed (Fig. S7). The results collectively validate the safety profile of the DBMNPs, emphasizing their suitability for co-delivery of both hydrophilic and hydrophobic drugs. Discussions In this study, we developed a novel DBMNPs capable of co-delivering hydrophilic and hydrophobic drugs. The successful fabrication of DBMNPs with embedded bubble structures represents a significant advancement in MN technology. Unlike DMNs, which are primarily limited to hydrophilic drug delivery, our design allows for the efficient encapsulation of hydrophobic agents within bubble cavities while maintaining the structural integrity of the MNs. To meet the treatment needs for acne, this study incorporated three antibacterial therapeutics (DPG, PIONIN, SA) with varying dissolution properties into the DBMNP. SEM and CLSM analyses confirmed the precise spatial distribution of the three therapeutics, hydrophilic drug DPG loaded in the main body of the MNs, hydrophobic PIONIN loaded in the bubbles, and drug SA loaded in the base layer. This compartmentalized loading strategy enhances therapeutic efficacy, addressing a critical limitation of conventional DMNs in the loading and delivery of hydrophobic agents. Mechanical characterization revealed that the DBMNPs possess sufficient strength (rupture stress: 4.7 ± 0.9 MPa) to penetrate the stratum corneum without fracture, achieving an insertion depth of ~ 350 µm in porcine skin. This ensures effective drug delivery to the pilosebaceous unit, the primary site of P. acnes colonization and inflammation. Importantly, the presence of bubbles did not compromise the mechanical robustness of the MNs, validating their structural feasibility for transdermal applications. In vitro drug release studies demonstrated distinct kinetic profiles for the three loaded agents (Fig. 4 c). SA, localized in the base layer, exhibited rapid release (~ 95% within 6 h), facilitating immediate anti-inflammatory and keratolytic effects. In contrast, PIONIN, encapsulated in the hydrophobic bubbles, displayed sustained release (~ 50% at 6 h), prolonging its antibacterial activity against P. acnes . DPG, loaded in the hydrophilic HA matrix, followed near-zero-order kinetics, ensuring prolonged anti-inflammatory action. This sequential release profile is critical for synergistic acne therapy, as it combines rapid symptom relief with sustained antimicrobial effects. The therapy evaluations in P. acnes induced acne vulgaris model demonstrate the superior therapeutic efficacy of DBMNPs over conventional topical treatments. The results of the animal experiments indicate that this DBMNPs can enhance drug delivery, significantly reduce ear swelling, eliminate P. acnes , and regulate the levels of inflammatory cytokines. Histological analyses corroborate these findings, showing minimal inflammatory infiltration and preserved tissue architecture in D/P/S DBMNPs treated group. Moreover, safety assessments further supported the clinical translatability of DBMNPs. No significant cytotoxicity was observed in 3T3 cells, and in vivo studies confirmed rapid skin recovery post-application without irritation. The absence of systemic toxicity, coupled with the patch’s painless and minimally invasive nature, positions DBMNPs as a patient-friendly alternative to oral or invasive therapies. In conclusion, this study demonstrates a novel MN platform that successfully addresses the key challenge of co-loading and co-delivering both hydrophilic and hydrophobic drugs. The unique bubble structure embedded within the MNs provides a loading space for hydrophobic agents while maintaining excellent mechanical strength and biocompatibility. The results confirmed its superior therapeutic efficacy against P. acnes infection and associated inflammation compared to conventional topical treatments. These findings position DBMNPs as a promising clinical solution for enhance acne vulgaris therapy. Future efforts will focus on optimizing the fabrication process to enhance the uniformity of bubbles, ensuring each one is precisely calibrated for optimal performance. This meticulous attention to detail aims to improve the consistency and reliability of the treatment, making it more effective for long-term applicability in addressing acne or other dermatological conditions. Materials And Methods Materials Low molecular weight sodium hyaluronate (HA-TLM, MW 10~100 kDa, Bloomage Biotechnology Corporation Limited, Cosmetic Grade), Low molecular weight sodium hyaluronate (HA-TLM, MW 200~400 KDa, Bloomage Biotechnology Corporation Limited, Cosmetic Grade), Sulfonyl rhodamine B (SRB, Shanghai Yuanye Bio-Technology Co., Ltd, BS), Dipotassium Glycyrrhetate (DPG, Gansu Fanzhi Pharmaceutical Co.,Ltd, ≥96%), Quaternium-73 (PIONIN, Chengdu Youngshe Chemical Co.,Ltd, 98%), Salicylic acid (SA, Shanghai Aladdin Biochemical Technology Co., Ltd, ≥99%). Mouse IL-6 Uncoated ELISA kit and Mouse IL-10 Uncoated ELISA kit were purchased from Invitrogen. Fabrication of DBMNPs The DBMNPs were fabricated via two-step polymer solution casting method. Specifically, HA (MW 10 -100 kDa) and HA (MW 200 - 400 kDa) were mixed at a 1:1 mass ratio and dissolved in deionized water to prepare a 10% (w/v) polymer solution. DPG and SA were mixed with the HA polymer solution (10%) to prepare 1 % (w/v) DPG-HA solution and 1 % (w/v) SA-HA solution, respectively. PIONIN was dissolved in anhydrous ethanol to prepare 0.002% (w/v) PIONIN-ethanol solution. The mixture was stirred vigorously to ensure complete dissolution and then centrifuged at 3500 rpm for 5 min to remove bubbles. First, the DPG-HA solution was cast onto a polydimethylsiloxane (PDMS) mold to form MNs tip under vacuum for 45 min and then removed excess solution. The mold was dried at room temperature for 30 min, and then PIONIN-ethanol solution (10 μL) was added to the mold under vacuum for 2 min. Secondly, SA-HA solution (300 μL) was added as MNs base and dried at room temperature for 24 h. Finally, the drugs loaded DBMNPs were obtained after carefully demolding them from the PDMS molds with an adhesive plate. In addition, blank DBMNPs without drugs were also prepared. Characterization of morphology The morphology of DBMNPs was analyzed using optical microscopy (SZXI2, SOPTOP, China), Confocal Laser Scanning Microscope (FV 3000, Olympus, Japan) and scanning electron microscopy (SEM, SU8010, Hitachi, Japan). For SEM imaging, DBMNPs samples were sputter-coated with a 5 nm gold layer under vacuum to enhance conductivity. In order to analyze the interface structure of the bubble, we firstly observed the overall morphology of the MN under an optical microscope, and the position of the maximum diameter of the bubble was located. Subsequently, a precision cutting blade was used to perform cross-sectional cutting at this position to obtain a sample containing the maximum cross-sectional area of the bubble. The samples after cutting were characterized using SEM to analyze the bubble structure. Moreover, to visualizes drug distribution and 3D structure, MNs were labeled with three fluorescent dyes including SRB (main body), FITC (bubble regions), and Cy5 (basement). Sequential Z-stack acquisition (step size 50 μm, total depth 550 μm) was performed using a laser scanning confocal microscope. 3D reconstructions were generated using NIS-Elements Viewer (V. 5.21.00). Characterization of mechanical properties The mechanical properties of individual MNs on the patch were evaluated using a microparticle strength tester (Microforce Measurement LTD, UK, MF-WSF1/Type1) (Fig. S2). A 10×10 MN array was prepared, and 50 randomly selected MNs were subjected to single-needle mechanical testing. The probe of the tester was aligned with the tip of a single MNs and compressed vertically at a constant speed of 20 μm/s until the maximum force the probe can withstand. Stress-strain curves were recorded to analyze the compressive strength and elasticity of the MNs. For the insertion test, the main body of DBMNPs were loaded with SRB dye (0.2% w/v) dissolved in deionized water, subsequently inserted into cadaver porcine skin samples and maintained in position for 5 min. Following removal, the skin specimens were sectioned along the penetration axis using a surgical scalpel. The insertion depth and dye distribution patterns were analyzed through optical microscopy (SZXI2, SOPTOP, China). Dissolving property of DBMNPs in vitro Cadaver porcine skin samples were mounted on glass slides prior to experimentation. DBMNPs were initially examined under optical microscopy (SZXI2, SOPTOP, China) prior to skin insertion, designated as the 0 s timepoint. Subsequently, the MNs were vertically inserted into the skin samples and removed after predetermined intervals (10 s, 20 s, 30 s, 60 s, 120 s). The residual tip length of retrieved MNs was quantitatively analyzed through optical microscopy imaging. Cytotoxicity evaluation The cytotoxicity of MN extracts was assessed using the CCK-8 assay with 3T3 fibroblast cells. Cells were cultured in 1640 medium and divided into five groups, including blank DBMNPs, SA loaded DBMNPs, loaded DBMNPs, loaded DBMNPs, and D/P/S loaded DBMNPs. The concentrations range of the MN matrix from 25 μg/mL to 800 μg/mL in a geometric gradient. After 24 hours of incubation, cell viability was calculated using the formula: Where A treated , A blank , and A 0 represent the absorbance values of treated wells (cells + CCK-8 + MN extract), blank wells (medium + CCK-8 without cells), and control wells (medium + cells + CCK-8 without MN extract), respectively. Drug release of DBMNPs in vitro The release profile of DPG, PIONIN and SA from DBMNPs was determined using the dialysis-bag method. For DPG and SA, three pieces of drug-loaded DBMNPs were inserted into a pre-treated dialysis bag (MWCO 3.5 kDa), the air was gently expelled and the bag was sealed. The dialysis bag was then immersed in 9 mL of PBS (pH 7.4) and shaken at 300 rpm in a 37 °C water bath. At 1, 2, 3, 5, 10, 15, 20, 30, 60, 120, 240 and 360 min, 300 µL aliquots were withdrawn and immediately replaced with the same volume of fresh pre-warmed medium. The samples were filtered through a 0.22 µm membrane and analyzed by HPLC. DPG was separated on a C18 column (250 mm × 4.6 mm, 5 µm) using a gradient of methanol (Table S1) and 0.06 % phosphoric acid at 1.0 mL/min, 25 °C, injection volume 20 µL and detection at 250 nm. SA was analyzed under the same chromatographic conditions except that a 30:70 (v/v) mixture of methanol and 0.1 mol/L NaH₂PO₄ was used as the mobile phase, injection volume was 10 µL and detection wavelength was 231 nm. For PIONIN, the release solvent consists of 1×PBS, ethyl alcohol, and Tween-80 in a ratio of 79:19:2 (v/v/v). And the drug-loaded DBMNPs were then sealed in a similarly pre-treated dialysis bag (MWCO 3.5 kDa) and immersed in 8 mL of the solvent. The system was agitated at 300 rpm and 100 µL samples were collected at the same time points, each replaced with an equal volume of fresh pre-warmed solvent. PIONIN concentration was determined by measuring absorbance at 411 nm with a microplate reader. Antibacterial activities P. acnes (ATCC 6919) were selected for antibacterial testing. Bacterial colonies were streaked onto modified reinforced clostridial agar and incubated anaerobically at 37°C for 48 hours. Single colonies were transferred to modified reinforced clostridial broth and cultured to the logarithmic growth phase (~1×10 7 CFU/mL). The bacterial suspension was diluted and co-cultured with MNs (200 μL per well) under anaerobic conditions at 37°C for 24 hours. Test groups included control, D/P/S solution, Blank DBMNPs, and D/P/S DBMNPs. Post-incubation, bacterial viability was assessed via agar plate coating and SEM imaging of morphological changes. Morphological changes of bacteria Scanning electron microscopy (SEM) was used to observe the morphological changes of bacteria incubated with dissolved bubble MN patches. The bacterial samples were subjected to gradient dehydration using 15%, 30%, 45%, 60%, 75%, 90%, and 100% ethanol (15 min per step), followed by fixation with 4% paraformaldehyde at 4°C overnight. Fixed specimens were mounted on silicon wafers, air-dried, and imaged using SEM. Animals study Six-week-old male BALB/c mice were obtained from the Charles River Laboratories (Beijing Vitong Lihua Experimental Animal Technology Co., Ltd., Beijing, China). All the experimental procedures were conducted and the animals were treated according to the Guide for the Care and Use of Laboratory Animals published by the Institutional Animal Care and Use Committee (IACUC), which had been approved by the Animal Ethics Committee of Tsinghua University (Approval ID: F124). Acne model was induced via intradermal injection of a P. acnes suspension (20 μL per mouse, total dose ~1×10 7 CFU) into the right ear pinna. Mice were divided into five groups (n=3 per group), including untreated group (Health), acne model without any treatment group (Model), the group treated with a topical drug solution (D/P/S Solution), the group treated with drug free DBMNPs (blank DBMNPs), and the group treated with DBMNPs loaded with drugs (D/P/S DBMNPs). Treatments were administered once daily for three consecutive days starting from day 0. Ear thickness measurements were recorded daily, and all mice were euthanized on day 3 for tissue harvest. Inflammatory response and histological analysis in vivo The inflammatory response was quantitatively assessed by measuring interleukin-6 (IL-6) and interleukin-10 (IL-10) levels in ear tissue homogenates. Briefly, homogenized tissues were centrifuged at 8000 rpm for 20 min at 4°C, and cytokine concentrations in the supernatants were determined using enzyme-linked immunosorbent assay (ELISA) kits following the manufacturer’s protocols. Absorbance values at 450 nm were measured with a microplate reader (Synergy H1, BioTek, USA) to calculate cytokine concentrations. For histological evaluation, excised ear tissues were fixed in 4% paraformaldehyde, embedded in paraffin, and sectioned into 5 μm slices. Hematoxylin and eosin (H&E) staining was performed to analyze tissue morphology and inflammatory infiltration. Statistical analysis Data were expressed as mean ± standard deviation (SD) from triplicate experiments. Measurements were standardized using ImageJ software (NIH, USA). Statistical significance between groups was analyzed using one-way analysis of variance (ANOVA) with Tukey’s post hoc test. All statistical calculations and data visualization were performed using Origin Pro 2022 (Origin Lab Corporation, USA). Significance levels were defined as *p < 0.05, **p < 0.01, and ***p < 0.001. Declarations Competing interests: The authors declare no competing interests. Data and materials availability All data are available in the main text or the supplementary materials. Author contributions: Oversaw the research: C.Y. Zhang, Designed the research strategy: X. Zhang, X. Zhao and Y. Li, Prepared MNPs and test strip: Y. Li, X. Zhao, W. Zhang and X. Zhang, Performance characterization: X. Zhang, Y. Chen and H. Jia, Conceptualization: Y. Li, X. Zhang, Z. Zhang and H. Jia, Writing—original draft: X. Zhang and X. Zhao, Writing—review & editing: Z. Zhang and C.Y. Zhang. Acknowledgments The authors greatly acknowledge the Key Research and Development Program of the Ministry of Science and Technology [2023YFA0914300 (2023YFA0914304)], fund from Shanghai Jahwa United Co., Ltd., National Natural Science Foundation of China (22278242), Guangdong Innovative and Entrepreneurial Research Team Program (2023ZT10C040), Shenzhen Technology and Innovation Commission (KCXFZ20230731094459001, KCXFZ20240903093102004), Shenzhen International Graduate School at Tsinghua University (HW2023009, JC2021011). References Tuchayi, S. M. et al. Acne vulgaris. Nature Reviews Disease Primers 1, 15029 (2015). Rajput, I. & Anjankar, V. P. Side effects of treating acne vulgaris with isotretinoin: A systematic review. Cureus 16, e55946 (2024). O’Neill, A. M. et al. 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Ultrasound-triggered interfacial engineering-based microneedle for bacterial infection acne treatment. Science Advances 9, eadf0854 (2023). Jan D. Bos, M. M. H. M. M. The 500 dalton rule for the skin penetration of chemical compounds and drugs. Experimental Dermatology 9, 165–169 (2000). Zhang, T. et al. Active pharmaceutical ingredient poly(ionic liquid)-based microneedles for the treatment of skin acne infection. Acta Biomaterialia 115, 136–147 (2020). Seok, J. et al. Effects of intradermal radiofrequency treatment and intense pulsed light therapy in an acne-induced rabbit ear model. Scientific Reports 9, 5056 (2019). Reynolds, R. V. et al. Guidelines of care for the management of acne vulgaris. Journal of the American Academy of Dermatology 90, 1006.e1001-1006.e1030 (2024). Jamaledin, R. et al. Advances in antimicrobial microneedle patches for combating infections. Advanced Materials 32, 2002129 (2020). Ertas, Y. N. et al. Diagnostic, therapeutic, and theranostic multifunctional microneedles. Small 20, e2308479 (2024). Liu, Z. et al. Multichannel microneedle dry electrode patches for minimally invasive transdermal recording of electrophysiological signals. Microsystems & Nanoengineering 10, 92 (2024). Jin, C. et al. A wearable self-aid microneedle chip based on actively transdermal delivery of epinephrine. Microsystems & Nanoengineering 11, 72 (2025). Sartawi, Z., Blackshields, C. & Faisal, W. Dissolving microneedles: Applications and growing therapeutic potential. Journal of Controlled Release 348, 186–205 (2022). Arya, J. et al. Tolerability, usability and acceptability of dissolving microneedle patch administration in human subjects. Biomaterials 128, 1–7 (2017). Bhadale, R. S. & Londhe, V. Y. Solid microneedle assisted transepidermal delivery of iloperidone loaded film: Characterization and skin deposition studies. Journal of Drug Delivery Science and Technology 79, 104028 (2023). Zhang, L. et al. Coated porous microneedles for effective intradermal immunization with split influenza vaccine. Acs Biomaterials Science & Engineering 9, 6880–6890 (2023). Zhang, Z., Du, G., Sun, X. & Zhang, Z. Viscoelastic properties of polymeric microneedles determined by micromanipulation measurements and mathematical modelling. Materials 16, 1769 (2023). Laszlo, E., De Crescenzo, G., Nieto-Arguello, A., Banquy, X. & Brambilla, D. Superswelling microneedle arrays for dermal interstitial fluid (prote)omics. Advanced Functional Materials 31, 2106061 (2021). Xing, M. et al. Preparation and evaluation of dissolving microneedle loaded with azelaic acid for acne vulgaris therapy. Journal of Drug Delivery Science and Technology 75, 103667 (2022). Thantaviriya, S. et al. Efficacy and safety of detachable microneedle patch containing triamcinolone acetonide in the treatment of inflammatory acne. Clinical Cosmetic and Investigational Dermatology 16, 1431–1441 (2023). Wang, Q. et al. Dissolving hyaluronic acid-based microneedles to transdermally deliver eugenol combined with photothermal therapy for acne vulgaris treatment. Acs Applied Materials & Interfaces 16, 21595–21609 (2024). Zhang, J. et al. A novel natural polysaccharide dissolving microneedle capable of adsorbing pus to load egcg for the treatment of acne vulgaris. Materials & Design 238 (2024). Zheng, M., Sheng, T., Yu, J., Gu, Z. & Xu, C. Microneedle biomedical devices. Nature Reviews Bioengineering 2, 324–342 (2024). Yin, Y., Wu, A., Zhou, H., Huang, Z. & Zang, H. Azelaic acid/β-cyclodextrin loaded hyaluronic acid-based dissolving microneedle for anti-acne application. Colloids and Surfaces A: Physicochemical and Engineering Aspects 707, 135890 (2025). Davis, S. P., Landis, B. J., Adams, Z. H., Allen, M. G. & Prausnitz, M. R. Insertion of microneedles into skin: Measurement and prediction of insertion force and needle fracture force. Journal of Biomechanics 37, 1155–1163 (2004). Additional Declarations There is no conflict of interest Supplementary Files SupplementaryMaterial.docx Supplementary materials for the submission Cite Share Download PDF Status: Published Journal Publication published 24 Nov, 2025 Read the published version in Microsystems & Nanoengineering → Version 1 posted Editorial decision: revise 27 Aug, 2025 Review # 1 received at journal 25 Aug, 2025 Review # 2 received at journal 23 Aug, 2025 Review # 3 received at journal 19 Aug, 2025 Reviewer # 3 agreed at journal 12 Aug, 2025 Reviewer # 2 agreed at journal 05 Aug, 2025 Reviewer # 1 agreed at journal 04 Aug, 2025 Reviewers invited by journal 04 Aug, 2025 Submission checks completed at journal 04 Aug, 2025 Editor assigned by journal 01 Aug, 2025 First submitted to journal 01 Aug, 2025 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. 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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-7269052","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":495344744,"identity":"a7782045-08b8-4d4b-ad00-cff6c6d582ff","order_by":0,"name":"Can Yang Zhang","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0002-6975-5781","institution":"Tsinghua University","correspondingAuthor":true,"prefix":"","firstName":"Can","middleName":"Yang","lastName":"Zhang","suffix":""},{"id":495344745,"identity":"1d7a69fb-7ae7-4b7b-a372-549301b41ef8","order_by":1,"name":"Xiaopeng Zhang","email":"","orcid":"","institution":"Tsinghua University","correspondingAuthor":false,"prefix":"","firstName":"Xiaopeng","middleName":"","lastName":"Zhang","suffix":""},{"id":495344746,"identity":"5e7da746-9c59-4848-8043-f1c5ef1f2c12","order_by":2,"name":"Xiaotong Zhao","email":"","orcid":"","institution":"Tsinghua university","correspondingAuthor":false,"prefix":"","firstName":"Xiaotong","middleName":"","lastName":"Zhao","suffix":""},{"id":495344747,"identity":"f362ae19-590f-49cf-9dcb-7168943c9b23","order_by":3,"name":"Yiting Li","email":"","orcid":"","institution":"Tsinghua University","correspondingAuthor":false,"prefix":"","firstName":"Yiting","middleName":"","lastName":"Li","suffix":""},{"id":495344748,"identity":"7315da8a-3ce5-4eb8-a4c5-c5278068beae","order_by":4,"name":"Wanyue Zhang","email":"","orcid":"","institution":"Tsinghua University","correspondingAuthor":false,"prefix":"","firstName":"Wanyue","middleName":"","lastName":"Zhang","suffix":""},{"id":495344749,"identity":"35f64dc6-cef1-4253-9a02-dd2c13d16bf1","order_by":5,"name":"Yuanyuan Chen","email":"","orcid":"","institution":"Shanghai Jahwa United Co. Ltd.","correspondingAuthor":false,"prefix":"","firstName":"Yuanyuan","middleName":"","lastName":"Chen","suffix":""},{"id":495344750,"identity":"39def264-bc52-4b36-b691-49802c6a3e96","order_by":6,"name":"Haidong Jia","email":"","orcid":"","institution":"Shanghai Jahwa United Co. Ltd.","correspondingAuthor":false,"prefix":"","firstName":"Haidong","middleName":"","lastName":"Jia","suffix":""},{"id":495344751,"identity":"c986c3a0-9864-42d7-bb67-2cd714d82f54","order_by":7,"name":"Zhibing Zhang","email":"","orcid":"","institution":"University of Birmingham","correspondingAuthor":false,"prefix":"","firstName":"Zhibing","middleName":"","lastName":"Zhang","suffix":""}],"badges":[],"createdAt":"2025-08-01 08:26:05","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7269052/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7269052/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41378-025-01079-y","type":"published","date":"2025-11-24T05:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":88502657,"identity":"7a5ac95c-d65f-425a-933e-720f22ada683","added_by":"auto","created_at":"2025-08-07 06:59:45","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":499051,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic illustration of DBMNPs for acne treatment. (DBMNPs, dissolved bubble microneedle patches; HA, hyaluronic acid; SA, Salicylic acid; DPG, Dipotassium glycyrrhizinate.)\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-7269052/v1/9cf006d7d3ce8011d593d033.png"},{"id":88500423,"identity":"8bf2a56f-e337-415f-852e-881e3e8336b4","added_by":"auto","created_at":"2025-08-07 06:51:46","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":669716,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Schematic of fabrication process of drugs co-loaded DBMNPs. (b) SEM images of three drugs co-loaded DBMNPs. (c) Optical microscope images and (d) 3D reconstruction images of three drugs co-loaded DBMNPs. (e) Typical CLSM images of three drugs co-loaded DBMNPs (main body, bubble, and base were stained with SRB, FITC, and Cy5, respectively), scale: 200 µm.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-7269052/v1/688151e0a0a7c2c0ffed76f1.png"},{"id":88500421,"identity":"e6462af2-a176-42dc-8277-45e564841edf","added_by":"auto","created_at":"2025-08-07 06:51:46","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":740313,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Force-displacement curves obtained from the compression of single MN (n= 50). Inset: different status of single MN during compression by microparticle strength tester. (b) Rupture stress and (c) Young’s modulus of the DBMNPs calculated based on force-displacement curves using Microneedle Strength Analysis Software. (d) Optical microscope image of cadaver porcine skin after insertion by DBMNPs (stained with SRB) and enlarged cross-sectional images.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-7269052/v1/9a2a8886f5fa83e1fb396405.png"},{"id":88500419,"identity":"b21c5786-5808-46e3-9591-dd086933fea1","added_by":"auto","created_at":"2025-08-07 06:51:45","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":890354,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Optical microscope images and (b) Remaining height ratio of DBMNPs after penetration into cadaver porcine skin at different time points (0, 10, 20, 30, 60, 120 s). (c) Cumulative release of drugs loaded in DBMNPs using dialysis method. Inset: cumulative release in the first 30 minutes. (d) Cytotoxicity of DBMNPs extract in 3T3 cells. (e) Agar plate coating results of \u003cem\u003eP. acnes \u003c/em\u003eafter co-culture with each group. (f) \u003cem\u003eIn\u003c/em\u003e \u003cem\u003evitro\u003c/em\u003e inhibition of \u003cem\u003eP. acnes \u003c/em\u003ein each group. (D/P/S solution: solution containing DPG, PIONIN, and SA; D/P/S DBMNPs: DBMNPs containing DPG, PIONIN, and SA, n = 3 for each group.). All calculated data are presented as mean ± standard deviation. Statistical significance between the antibacterial rate in each group was calculated. The significance levels were analyzed by using one-way analysis of variance (ANOVA). ***p \u0026lt; 0.001; ns: p \u0026gt; 0.05, not significant difference.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-7269052/v1/cd0b69eaee8c70771056c90f.png"},{"id":88500432,"identity":"ca899896-44b7-4684-a1b4-e593b87d4579","added_by":"auto","created_at":"2025-08-07 06:51:46","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":743949,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Schematic description and timeline for the animal experiment. (b) Appearance changes in the right ear of mice in different treatment groups. (c) Thickness of the right ear of mice in each group during therapy. (d) Quantitative analysis of IL-6 levels and (e) IL-10 levels in the right ear tissue after therapy. (f) Photomicrographs of right ear tissue stained with H\u0026amp;E in each group after therapy, black arrows mark inflammatory cells. n = 3 for each group. All calculated data are presented as mean ± standard deviation. The significance levels were analyzed by using one-way analysis of variance (ANOVA). **p ≤ 0.01; ***p ≤ 0.001; ****p ≤ 0.0001; ns: p \u0026gt; 0.05, no significant difference.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-7269052/v1/e74aaca583ff05746faee029.png"},{"id":96699941,"identity":"c37ce048-fa96-41d1-a07a-e20d87269bba","added_by":"auto","created_at":"2025-11-25 08:17:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4483669,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7269052/v1/ad6c3516-a338-43dc-b90f-c7ab9e8b3047.pdf"},{"id":88500426,"identity":"b3be6242-3557-45e7-81cd-b13072766248","added_by":"auto","created_at":"2025-08-07 06:51:46","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":4302573,"visible":true,"origin":"","legend":"Supplementary materials for the submission","description":"","filename":"SupplementaryMaterial.docx","url":"https://assets-eu.researchsquare.com/files/rs-7269052/v1/5d2bac883f9e33634e694c0f.docx"}],"financialInterests":"There is no conflict of interest","formattedTitle":"Dissolved Bubble Microneedle Patches for Co-Delivery of Hydrophobic and Hydrophilic Drugs to Improve Acne Vulgaris Therapy","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAcne vulgaris, a common dermatological condition, is characterized by chronic inflammation of the pilosebaceous unit\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u003c/sup\u003e. It is particularly prevalent among adolescents and imposes a significant clinical burden globally, manifesting as erythematous papules, pustules, and other lesions\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e,\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. Notably, acne vulgaris frequently results in long-term consequences, such as permanent scarring and psychological distress, which can severely affect patients\u0026rsquo; appearance, mental health, and overall quality of life.\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. The pathogenesis of acne vulgaris is multifactorial, involving excessive sebum production and proliferation of Propionibacterium acnes (\u003cem\u003eP. acnes\u003c/em\u003e)\u003csup\u003e\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. Consequently, effective acne vulgaris management necessitates a multiple therapeutic approach combining localized antibacterial and anti-inflammatory strategies\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e,\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eCurrent clinical interventions for the management of acne vulgaris include topical drug applications\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e, oral medication, and light-based therapies\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e,\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. However, these approaches are fraught with several limitations, such as prolonged treatment durations, the emergence of antibiotic resistance, intolerable adverse effects, and poor patient compliance\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. Namely, topical applications are obstructed by the stratum corneum barrier, drugs with a molecular weight exceeding 500 Daltons typically exhibit limited absorption\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. As for oral medications, such as salicylic acid (SA), usually cause side effects including gastrointestinal reactions, liver and kidney damage\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e. Laser therapies can target sebaceous glands or bacterial populations but require multiple sessions. Their effectiveness for percutaneous varies across different skin types, and may cause transient erythema or hyperpigmentation\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. Recently, the combined use of hydrophilic drugs and hydrophobic drugs is a commonly recommended clinical approach\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. Notably, certain agents, such as Quaternium-73 (PIONIN), which exhibit superior safety and good antibacterial properties, are regarded as highly promising components for the treatment of acne vulgaris. However, their limited water solubility and low permeability substantially impede their commercial applicability\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. Collectively, these challenges highlight the urgent need for drug delivery platforms that combine minimally invasive administration and enhanced drug penetration, especially for hydrophobic agents.\u003c/p\u003e\u003cp\u003eMicroneedles (MNs), a type of micrometer-sized needles typically less than 1000 \u0026micro;m in length, can penetrate the stratum corneum and deliver drugs directly into the dermis\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e,\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e. It enables efficient deliver both small molecules and macromolecules, offering a painless, minimally invasive, and high effective transdermal drug delivery strategy\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. Additionally, MNs can achieve localized drug accumulation in deep lesion sites while avoiding systemic toxicity. Clinical trials have demonstrated that MN technology is well tolerated, easily usable and strongly accepted \u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. There are several types of MNs including solid MNs\u003csup\u003e\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e\u003c/sup\u003e, coated MNs\u003csup\u003e\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e, dissolving MNs (DMNs)\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e, and swelling MNs\u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e\u003c/sup\u003e. Among them, DMNs are regarded as one of the most promising delivery platforms for clinical transformation due to their advantages such as good biocompatibility of materials, degradability, low risk of cross-infection, and flexible drug delivery\u003csup\u003e\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e,\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. Multiple studies have demonstrated the significant efficacy of DMNs in delivering antimicrobial peptides, anti-inflammatory molecules, or other agents in acne vulgaris treatment\u003csup\u003e\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e,\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e\u003c/sup\u003e. However, the matrix materials of DMNs are typically composed of water-soluble polymers such as polyvinyl alcohol (PVA) and hyaluronic acid (HA), inherently limiting the incorporation and stability of lipophilic agents and restricting their broader application in acne vulgaris therapy\u003csup\u003e\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e,\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e. Therefore, enhancing the drug loading and co-delivery of hydrophilic and hydrophobic drugs remain key challenges for DMNs.\u003c/p\u003e\u003cp\u003eGiven these limitations and objectives, we designed and fabricated a dissolved bubble microneedle patches (DBMNPs) for the co-delivery of both hydrophilic and hydrophobic drugs to improve acne vulgaris therapy. Briefly, the DBMNPs were fabricated using hyaluronic acid (HA), with hollow bubble structures embedded within the MNs to encapsulate hydrophobic drugs (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The entire manufacturing process of DBMNPs is rapid and cost-effective. The patches facilitate the spatial segregation and temporally controlled release of three distinct therapeutics, including hydrophilic dipotassium glycyrrhizinate (DPG) loaded in the main body, hydrophobic PIONIN loaded in the bubbles, and salicylic acid (SA) loaded in the base layer. The prepared co-loaded DBMNPs showed high mechanical strength, good biocompatibility, and high antimicrobial properties against \u003cem\u003eP. acnes.\u003c/em\u003e Moreover, animal studies demonstrated that the DBMNPs patches are highly effective in treating acne vulgaris.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cb\u003eFabrication and Characterization of DBMNPs\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe HA-based hydrophobic-hydrophilic drugs co-loaded DBMNPs are successfully fabricated \u003cem\u003evia\u003c/em\u003e PDMS molds using micro-casting film-forming method (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). The structure of the drugs co-loaded DBMNPs (10 \u0026times; 10 array) are confirmed using scanning electron microscope (SEM, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb) and optical microscope (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec). Bubbles embedded in the DBMNPs are uniformly distributed within the MNs, with an average diameter of approximately 176 am and wall thickness of about 10 am (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). The average height of MN is confirmed to be 500\u0026ndash;550 mm, with a bottom diameter of approximately 300 my (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec). The tips of the MNs are sharp enough, making it easy to pierce into the skin. To further visually characterize the spatial distribution of the three drugs in the DBMNPs, a fluorescence labeling strategy and confocal laser scanning microscopy (CLSM) are utilized. Specifically, sulfonyl rhodamine B (SRB) is used to simulate hydrophilic DPG distribution in the main body of the MNs, FITC is used to simulate hydrophobic PIONIN distribution in the bubbles, and Cy5 is used to simulate SA distribution in the base layer. In detail, Z-stack scanning is performed along the axial direction of the MNs from the tip to the base, with a total scanning depth of 550 \u0026micro;m and an interlayer resolution of 50 \u0026micro;m. The 3D reconstruction results demonstrate that three drugs exhibit specific distributions within the MNs, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed. Namely, hydrophilic drug DPG was specifically localized at main body of the MNs (from Z\u0026thinsp;=\u0026thinsp;0 \u0026micro;m to 500 \u0026micro;m), hydrophobic drug PIONIN is selectively distributed in the bubble region (from Z\u0026thinsp;=\u0026thinsp;300 \u0026micro;m to 450 \u0026micro;m), and the hydrophilic drug SA is observed in the base layer (from Z\u0026thinsp;=\u0026thinsp;400 \u0026micro;m to 500 \u0026micro;m). This drug distribution pattern highly aligned with the structural features of the MN designed in the earlier stage, confirming that the bubble MNs enable spatially controlled drug loading (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ee). Summarily, the designed hydrophobic and hydrophilic drugs co-loaded DBMNPs were successfully fabricated based on HA matrix using micro-casting film-forming method and the three drugs are specifically loaded in the main body, bubbles, and base parts of the MNs for precise transdermal delivery. Moreover, the concentration of each drug for fabrication of DBMNPs were optimized based on their proximity to the minimum effective threshold required for complete inhibition of \u003cem\u003eP. acnes\u003c/em\u003e, with 1% DPG, 1% SA, and 0.002% PIONIN demonstrating potent bactericidal properties (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eMechanical performance of DBMNPs\u003c/b\u003e\u003c/p\u003e\u003cp\u003eGiven the critical role of mechanical properties in effective transdermal delivery, the mechanical property of individual DBMNs was rigorously evaluated. Single-needle compression testing was performed using a microparticle strength tester (Fig. S2). Randomly select 50 MNs from the drug co-loaded DBMNPs to test the single-needle mechanical property. The force-displacement curves of DBMNPs clearly indicate that the force increased with the increase of displacement, and only the tip of the MN bends without breaking after compression test (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea). The average rupture force and Young\u0026rsquo;s modulus of single MN is 4.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9 MPa (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb) and 144.8\u0026thinsp;\u0026plusmn;\u0026thinsp;44.8 MPa (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec), respectively. These results substantially surpass the reported minimum force required for MNs insertion into human skin\u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. Furthermore, insertion capability of the drugs co-loaded DBMNPs were assessed using porcine cadaver skin model. The results demonstrated that the DBMNPs consistently achieved an average insertion depth of approximately 350 \u0026micro;m (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed), confirming the existence of bubbles does not impair the penetration ability of MNs.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eDrug release of DBMNPs\u003c/b\u003e \u003cb\u003ein vitro\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe dissolution property of DBMNPs were evaluated based on the pig cadaver skin. The MNs arranged on the DBMNPs initially maintained their structural integrity at 0 s, featuring sharp tips and uniformly distributed bubble cavities, and almost completely dissolved at 120 s (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea-b), which is particularly advantageous for patient compliance while ensuring prompt drug delivery. The drug release profiles of three therapeutic agents from DBMNPs were evaluated using the dialysis-bag method. The drug concentration was calculated based on a pre-validated standard curve (Fig. S3). The release results as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec, an initial burst release was observed for SA, with over 50% of the payload released within the first 30 min (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec, inset) and the cumulative release amount reached approximately 95% at 6 h. As for DPG, localized at the main body of the DBMNPs, exhibited near-zero-order release kinetics during the initial 4 h, and approximately 70% was released at 6 h. In contrast, PIONIN, loaded within the bubble cavities, demonstrated significantly slower release due to its limited aqueous solubility, achieving about 50% cumulative release at the 6 h. The results indicated the DBMNPs enable the release of encapsulated therapeutics after application, ensuring substantial local drug availability at the target site.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eBiocompatibility and Antibacterial performance of DBMNPs\u003c/b\u003e \u003cb\u003ein vitro\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe biocompatibility of DBMNPs was evaluated in 3T3 cells \u003cem\u003evia\u003c/em\u003e CCK-8 assay. The results indicated that cell viability of remained above 80% across a broad concentration range (25\u0026ndash;800 \u0026micro;g/mL), demonstrating good biocompatibility of the DBMNPs (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed). The antibacterial performance of three drugs co-loaded DBMNPs (D/P/S DBMNPs) was evaluated through agar plate assays. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ee, both D/P/S DBMNPs and D/P/S solution group exhibited comparable antimicrobial efficacy against \u003cem\u003eP. acnes\u003c/em\u003e, inducing severe morphological damage to bacterial cells such as membrane collapse and cytoplasmic leakage. In contrast, blank DBMNPs group showed limited antibacterial activity, as evidenced by incomplete colony reduction on agar plates and a small portion of the bacterial morphology ruptured in SEM images (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ee). Quantitative assessment of antibacterial rates (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ef) further confirmed the superior antimicrobial performance of three drugs co-loaded DBMNPs. These results collectively demonstrated that the antimicrobial mechanism of D/P/S DBMNPs is primarily mediated by the bioactive components released from the MNs rather than passive physical interactions.\u003c/p\u003e\u003cp\u003e\u003cb\u003eEvaluation of DBMNPs for acne vulgaris therapy\u003c/b\u003e \u003cb\u003ein vivo\u003c/b\u003e\u003c/p\u003e\u003cp\u003eInfection with \u003cem\u003eP. acnes\u003c/em\u003e is a leading cause of acne vulgaris. To evaluate the in vivo efficacy of DBMNPs loaded with three drugs, an acne vulgaris model was established by intradermally injecting \u003cem\u003eP. acnes\u003c/em\u003e into the right ear of BALB/c mice. Briefly, the mice were divided into five groups: untreated group (Health), untreated acne model group (Model), treated with a topical drug solution group (D/P/S Solution), treated with drug-free DBMNPs group (blank DBMNPs), and treated with drug-loaded DBMNPs group (D/P/S DBMNPs). Treatments were administered once daily for three consecutive days starting from day 0. Ear thickness was measured daily, and all mice were humanely euthanized on the third day for tissue collection (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea). It can be seen that the DBMNP needles almost completely dissolved within 5 min of insertion into the ear skin (Fig. S4). The therapeutic results are displayed in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb, after 72 h \u003cem\u003eP. acnes\u003c/em\u003e injection, the right ears of all mice exhibited redness and swelling. Despite a three-day treatment, the symptoms persisted in the model group. Conversely, the redness and swelling symptoms in the groups treated with topical D/P/S solution, blank DBMNPs, and D/P/S DBMNPs showed a marked reduction, suggesting that all these groups are effective in treating acne vulgaris. Moreover, the symptoms of D/P/S DBMNPs group is superior to that of the blank DBMNPs group and D/P/S solution groups. This is because the DBMNPs effectively enhanced the transdermal absorption of three antimicrobial and anti-inflammatory agents with varying solubilities. Notably, although the D/P/S solution group was found to have the same antibacterial performance as D/P/S DBMNPs \u003cem\u003ein vitro\u003c/em\u003e, it failed to relieve the symptoms due to insufficient transdermal penetration into the \u003cem\u003eP. acnes\u003c/em\u003e rich pustular regions. The blank DBMNPs group demonstrated partial improvement in ear swelling, possibly attributable to the MNs create micropores, alleviating hypoxia in swollen regions and indirectly impairing the growth of anaerobic \u003cem\u003eP. acnes\u003c/em\u003e. Simultaneously, we recorded the variations in ear thickness of mice during treatment. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec, after 72 h of \u003cem\u003eP. acnes\u003c/em\u003e injection, the ear thickness of all mice increased from normal 0.2 mm to 0.6 mm or more. Mice treated with D/P/S DBMNPs exhibited a significant reduction in ear thickness over three days, indicating rapid resolution of swelling. In contrast, the model group and D/P/S Solution group showed similar increases in ear thickness, likely due to limited transdermal penetration of the topically applied solution.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eNext, the quantitative analysis of inflammatory cytokines demonstrated a significant reduction in pro-inflammatory IL-6 levels (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ed) and a concurrent increase in anti-inflammatory IL-10 (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ee) following treatment with D/P/S DBMNPs. Antimicrobial assessment \u003cem\u003evia\u003c/em\u003e agar plate assays (Fig. S5) revealed nearly complete elimination of \u003cem\u003eP. acnes\u003c/em\u003e colonies in the D/P/S DBMNPs treatment group. Histopathological examination (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ef) further supported these observations, showing markedly reduced inflammatory cell infiltration and maintained epidermal integrity in D/P/S DBMNPs-treated specimens, in stark contrast to the extensive neutrophilic infiltration observed in both untreated and solution-treated control groups. Furthermore, the safety of DBMNPs were also evaluated according to body weight and skin recovery after administration. All treatment groups, including D/P/S DBMNPs, blank MNs, and D/P/S Solution, exhibited stable body weight throughout the therapy (Fig. S6). To further assess the safety of DBMNPs administration, we recorded the changes in the skin of healthy mice after the MNs were inserted into their right ears. The study found that the micropores created by the DBMNPs became virtually invisible to the naked eye within 5 min, and no abnormal symptoms such as redness or swelling occurred in the mice\u0026rsquo;s ears after the patch removed (Fig. S7). The results collectively validate the safety profile of the DBMNPs, emphasizing their suitability for co-delivery of both hydrophilic and hydrophobic drugs.\u003c/p\u003e"},{"header":"Discussions","content":"\u003cp\u003eIn this study, we developed a novel DBMNPs capable of co-delivering hydrophilic and hydrophobic drugs. The successful fabrication of DBMNPs with embedded bubble structures represents a significant advancement in MN technology. Unlike DMNs, which are primarily limited to hydrophilic drug delivery, our design allows for the efficient encapsulation of hydrophobic agents within bubble cavities while maintaining the structural integrity of the MNs. To meet the treatment needs for acne, this study incorporated three antibacterial therapeutics (DPG, PIONIN, SA) with varying dissolution properties into the DBMNP. SEM and CLSM analyses confirmed the precise spatial distribution of the three therapeutics, hydrophilic drug DPG loaded in the main body of the MNs, hydrophobic PIONIN loaded in the bubbles, and drug SA loaded in the base layer. This compartmentalized loading strategy enhances therapeutic efficacy, addressing a critical limitation of conventional DMNs in the loading and delivery of hydrophobic agents.\u003c/p\u003e\u003cp\u003eMechanical characterization revealed that the DBMNPs possess sufficient strength (rupture stress: 4.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9 MPa) to penetrate the stratum corneum without fracture, achieving an insertion depth of ~\u0026thinsp;350 \u0026micro;m in porcine skin. This ensures effective drug delivery to the pilosebaceous unit, the primary site of \u003cem\u003eP. acnes\u003c/em\u003e colonization and inflammation. Importantly, the presence of bubbles did not compromise the mechanical robustness of the MNs, validating their structural feasibility for transdermal applications.\u003c/p\u003e\u003cp\u003eIn vitro drug release studies demonstrated distinct kinetic profiles for the three loaded agents (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec). SA, localized in the base layer, exhibited rapid release (~\u0026thinsp;95% within 6 h), facilitating immediate anti-inflammatory and keratolytic effects. In contrast, PIONIN, encapsulated in the hydrophobic bubbles, displayed sustained release (~\u0026thinsp;50% at 6 h), prolonging its antibacterial activity against \u003cem\u003eP. acnes\u003c/em\u003e. DPG, loaded in the hydrophilic HA matrix, followed near-zero-order kinetics, ensuring prolonged anti-inflammatory action. This sequential release profile is critical for synergistic acne therapy, as it combines rapid symptom relief with sustained antimicrobial effects.\u003c/p\u003e\u003cp\u003eThe therapy evaluations in \u003cem\u003eP. acnes\u003c/em\u003e induced acne vulgaris model demonstrate the superior therapeutic efficacy of DBMNPs over conventional topical treatments. The results of the animal experiments indicate that this DBMNPs can enhance drug delivery, significantly reduce ear swelling, eliminate \u003cem\u003eP. acnes\u003c/em\u003e, and regulate the levels of inflammatory cytokines. Histological analyses corroborate these findings, showing minimal inflammatory infiltration and preserved tissue architecture in D/P/S DBMNPs treated group. Moreover, safety assessments further supported the clinical translatability of DBMNPs. No significant cytotoxicity was observed in 3T3 cells, and \u003cem\u003ein vivo\u003c/em\u003e studies confirmed rapid skin recovery post-application without irritation. The absence of systemic toxicity, coupled with the patch\u0026rsquo;s painless and minimally invasive nature, positions DBMNPs as a patient-friendly alternative to oral or invasive therapies.\u003c/p\u003e\u003cp\u003eIn conclusion, this study demonstrates a novel MN platform that successfully addresses the key challenge of co-loading and co-delivering both hydrophilic and hydrophobic drugs. The unique bubble structure embedded within the MNs provides a loading space for hydrophobic agents while maintaining excellent mechanical strength and biocompatibility. The results confirmed its superior therapeutic efficacy against \u003cem\u003eP. acnes\u003c/em\u003e infection and associated inflammation compared to conventional topical treatments. These findings position DBMNPs as a promising clinical solution for enhance acne vulgaris therapy. Future efforts will focus on optimizing the fabrication process to enhance the uniformity of bubbles, ensuring each one is precisely calibrated for optimal performance. This meticulous attention to detail aims to improve the consistency and reliability of the treatment, making it more effective for long-term applicability in addressing acne or other dermatological conditions.\u003c/p\u003e"},{"header":"Materials And Methods","content":"\u003cp\u003e\u003cstrong\u003eMaterials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eLow molecular weight sodium hyaluronate (HA-TLM, MW 10~100 kDa, Bloomage Biotechnology Corporation Limited, Cosmetic Grade), Low molecular weight sodium hyaluronate (HA-TLM, MW 200~400 KDa, Bloomage Biotechnology Corporation Limited, Cosmetic Grade), Sulfonyl rhodamine B (SRB, Shanghai Yuanye Bio-Technology Co., Ltd, BS), Dipotassium Glycyrrhetate (DPG, Gansu Fanzhi Pharmaceutical Co.,Ltd, \u0026ge;96%), Quaternium-73 (PIONIN, Chengdu Youngshe Chemical Co.,Ltd, 98%), Salicylic acid (SA, Shanghai Aladdin Biochemical Technology Co., Ltd, \u0026ge;99%). Mouse IL-6 Uncoated ELISA kit and Mouse IL-10 Uncoated ELISA kit were purchased from Invitrogen.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFabrication of DBMNPs\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe DBMNPs were fabricated \u003cem\u003evia\u003c/em\u003e two-step polymer solution casting method. Specifically, HA (MW 10 -100 kDa) and HA (MW 200 - 400 kDa) were mixed at a 1:1 mass ratio and dissolved in deionized water to prepare a 10% (w/v) polymer solution. DPG and SA were mixed with the HA polymer solution (10%) to prepare 1 % (w/v) DPG-HA solution and 1 % (w/v) SA-HA solution, respectively. PIONIN was dissolved in anhydrous ethanol to prepare 0.002% (w/v) PIONIN-ethanol solution. The mixture was stirred vigorously to ensure complete dissolution and then centrifuged at 3500 rpm for 5 min to remove bubbles. First, the DPG-HA solution was cast onto a polydimethylsiloxane (PDMS) mold to form MNs tip under vacuum for 45 min and then removed excess solution. The mold was dried at room temperature for 30 min, and then PIONIN-ethanol solution (10 \u0026mu;L) was added to the mold under vacuum for 2 min. Secondly, SA-HA solution (300 \u0026mu;L) was added as MNs base and dried at room temperature for 24 h. Finally, the drugs loaded DBMNPs were obtained after carefully demolding them from the PDMS molds with an adhesive plate. In addition, blank DBMNPs without drugs were also prepared.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCharacterization of morphology\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe morphology of DBMNPs was analyzed using optical microscopy (SZXI2, SOPTOP, China), Confocal Laser Scanning Microscope (FV 3000, Olympus, Japan) and scanning electron microscopy (SEM, SU8010, Hitachi, Japan). For SEM imaging, DBMNPs samples were sputter-coated with a 5 nm gold layer under vacuum to enhance conductivity. In order to analyze the interface structure of the bubble, we firstly observed the overall morphology of the MN under an optical microscope, and the position of the maximum diameter of the bubble was located. Subsequently, a precision cutting blade was used to perform cross-sectional cutting at this position to obtain a sample containing the maximum cross-sectional area of the bubble. The samples after cutting were characterized using SEM to analyze the bubble structure. Moreover, to visualizes drug distribution and 3D structure, MNs were labeled with three fluorescent dyes including SRB (main body), FITC (bubble regions), and Cy5 (basement). Sequential Z-stack acquisition (step size 50 \u0026mu;m, total depth 550 \u0026mu;m) was performed using a laser scanning confocal microscope. 3D reconstructions were generated using NIS-Elements Viewer (V. 5.21.00).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCharacterization of mechanical properties\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe mechanical properties of individual MNs on the patch were evaluated using a microparticle strength tester (Microforce Measurement LTD, UK, MF-WSF1/Type1) (Fig. S2). A 10\u0026times;10 MN array was prepared, and 50 randomly selected MNs were subjected to single-needle mechanical testing. The probe of the tester was aligned with the tip of a single MNs and compressed vertically at a constant speed of 20 \u0026mu;m/s until the maximum force the probe can withstand. Stress-strain curves were recorded to analyze the compressive strength and elasticity of the MNs. For the insertion test, the main body of DBMNPs were loaded with SRB dye (0.2% w/v) dissolved in deionized water, subsequently inserted\u0026nbsp;into\u0026nbsp;cadaver porcine skin\u0026nbsp;samples and maintained in position for 5 min. Following removal, the skin specimens were sectioned along the penetration axis using a surgical scalpel. The insertion depth and dye distribution patterns were analyzed through optical microscopy (SZXI2, SOPTOP, China).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDissolving property of DBMNPs \u003cem\u003ein vitro\u003c/em\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCadaver porcine skin\u0026nbsp;samples were mounted on glass slides prior to experimentation. DBMNPs were initially examined under optical microscopy (SZXI2, SOPTOP, China) prior to skin insertion, designated as the 0 s timepoint. Subsequently, the MNs were vertically inserted into the skin samples and removed after predetermined intervals (10 s, 20 s, 30 s, 60 s, 120 s). The residual tip length of retrieved MNs was quantitatively analyzed through optical microscopy imaging.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCytotoxicity evaluation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe cytotoxicity of MN extracts was assessed using the CCK-8 assay with 3T3 fibroblast cells. Cells were cultured in 1640 medium and divided into five groups, including blank DBMNPs, SA loaded DBMNPs, loaded DBMNPs, loaded DBMNPs, and D/P/S loaded DBMNPs. The concentrations range of the MN matrix from 25 \u0026mu;g/mL to 800 \u0026mu;g/mL in a geometric gradient. After 24 hours of incubation, cell viability was calculated using the formula:\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\" width=\"322\" height=\"40\"\u003e\u003c/p\u003e\n\u003cp\u003eWhere A\u003csub\u003etreated\u003c/sub\u003e, A\u003csub\u003eblank\u003c/sub\u003e, and A\u003csub\u003e0\u003c/sub\u003e represent the absorbance values of treated wells (cells + CCK-8 + MN extract), blank wells (medium + CCK-8 without cells), and control wells (medium + cells + CCK-8 without MN extract), respectively.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDrug release of DBMNPs \u003cem\u003ein vitro\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe release profile of DPG, PIONIN and SA from DBMNPs was determined using the dialysis-bag method. For DPG and SA, three pieces of drug-loaded DBMNPs were inserted into a pre-treated dialysis bag (MWCO 3.5 kDa), the air was gently expelled and the bag was sealed. The dialysis bag was then immersed in 9 mL of PBS (pH 7.4) and shaken at 300 rpm in a 37 \u0026deg;C water bath. At 1, 2, 3, 5, 10, 15, 20, 30, 60, 120, 240 and 360 min, 300 \u0026micro;L aliquots were withdrawn and immediately replaced with the same volume of fresh pre-warmed medium. The samples were filtered through a 0.22 \u0026micro;m membrane and analyzed by HPLC. DPG was separated on a C18 column (250 mm \u0026times; 4.6 mm, 5 \u0026micro;m) using a gradient of methanol (Table S1) and 0.06 % phosphoric acid at 1.0 mL/min, 25 \u0026deg;C, injection volume 20 \u0026micro;L and detection at 250 nm. SA was analyzed under the same chromatographic conditions except that a 30:70 (v/v) mixture of methanol and 0.1 mol/L NaH₂PO₄ was used as the mobile phase, injection volume was 10 \u0026micro;L and detection wavelength was 231 nm. For PIONIN, the release solvent consists of 1\u0026times;PBS, ethyl alcohol, and Tween-80 in a ratio of 79:19:2 (v/v/v). And the drug-loaded DBMNPs were then sealed in a similarly pre-treated dialysis bag (MWCO 3.5 kDa) and immersed in 8 mL of the solvent. The system was agitated at 300 rpm and 100 \u0026micro;L samples were collected at the same time points, each replaced with an equal volume of fresh pre-warmed solvent. PIONIN concentration was determined by measuring absorbance at 411 nm with a microplate reader.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAntibacterial activities\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eP. acnes\u0026nbsp;\u003c/em\u003e(ATCC 6919) were selected for antibacterial testing. Bacterial colonies were streaked onto modified reinforced clostridial agar and incubated anaerobically at 37\u0026deg;C for 48 hours. Single colonies were transferred to modified reinforced clostridial broth and cultured to the logarithmic growth phase (~1\u0026times;10\u003csup\u003e7\u003c/sup\u003e CFU/mL). The bacterial suspension was diluted and co-cultured with MNs (200 \u0026mu;L per well) under anaerobic conditions at 37\u0026deg;C for 24 hours. Test groups included control, D/P/S solution, Blank DBMNPs, and D/P/S DBMNPs. Post-incubation, bacterial viability was assessed via agar plate coating and SEM imaging of morphological changes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMorphological changes of bacteria\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eScanning electron microscopy (SEM) was used to observe the morphological changes of bacteria incubated with dissolved bubble MN patches. The bacterial samples were subjected to gradient dehydration using 15%, 30%, 45%, 60%, 75%, 90%, and 100% ethanol (15 min per step), followed by fixation with 4% paraformaldehyde at 4\u0026deg;C overnight. Fixed specimens were mounted on silicon wafers, air-dried, and imaged using SEM.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAnimals study\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSix-week-old male BALB/c mice were obtained from the Charles River Laboratories (Beijing Vitong Lihua Experimental Animal Technology Co., Ltd., Beijing, China). All the experimental procedures were conducted and the animals were treated according to the Guide for the Care and Use of Laboratory Animals published by the Institutional Animal Care and Use Committee (IACUC), which had been approved by the Animal Ethics Committee of Tsinghua University (Approval ID: F124).\u0026nbsp;Acne model was induced via intradermal injection of a \u003cem\u003eP. acnes\u003c/em\u003e suspension (20 \u0026mu;L per mouse, total dose ~1\u0026times;10\u003csup\u003e7\u0026nbsp;\u003c/sup\u003eCFU) into the right ear pinna. Mice were divided into five groups (n=3 per group), including untreated group (Health), acne model without any treatment group (Model), the group treated with a topical drug solution (D/P/S Solution), the group treated with drug free DBMNPs (blank DBMNPs), and the group treated with DBMNPs loaded with drugs (D/P/S DBMNPs). Treatments were administered once daily for three consecutive days starting from day 0. Ear thickness measurements were recorded daily, and all mice were euthanized on day 3 for tissue harvest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInflammatory response and histological analysis \u003cem\u003ein vivo\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe inflammatory response was quantitatively assessed by measuring interleukin-6 (IL-6) and interleukin-10 (IL-10) levels in ear tissue homogenates. Briefly, homogenized tissues were centrifuged at 8000 rpm for 20 min at 4\u0026deg;C, and cytokine concentrations in the supernatants were determined using enzyme-linked immunosorbent assay (ELISA) kits following the manufacturer\u0026rsquo;s protocols. Absorbance values at 450 nm were measured with a microplate reader (Synergy H1, BioTek, USA) to calculate cytokine concentrations. For histological evaluation, excised ear tissues were fixed in 4% paraformaldehyde, embedded in paraffin, and sectioned into 5 \u0026mu;m slices. Hematoxylin and eosin (H\u0026amp;E) staining was performed to analyze tissue morphology and inflammatory infiltration.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistical analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData were expressed as mean \u0026plusmn; standard deviation (SD) from triplicate experiments. Measurements were standardized using ImageJ software (NIH, USA). Statistical significance between groups was analyzed using one-way analysis of variance (ANOVA) with Tukey\u0026rsquo;s post hoc test. All statistical calculations and data visualization were performed using Origin Pro 2022 (Origin Lab Corporation, USA). Significance levels were defined as *p \u0026lt; 0.05, **p \u0026lt; 0.01, and ***p \u0026lt; 0.001.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eCompeting interests:\u003c/h2\u003e\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\u003ch2\u003eData and materials availability\u003c/h2\u003e\u003cp\u003eAll data are available in the main text or the supplementary materials.\u003c/p\u003e\u003ch2\u003eAuthor contributions:\u003c/h2\u003e\u003cp\u003eOversaw the research: C.Y. Zhang, Designed the research strategy: X. Zhang, X. Zhao and Y. Li, Prepared MNPs and test strip: Y. Li, X. Zhao, W. Zhang and X. Zhang, Performance characterization: X. Zhang, Y. Chen and H. Jia, Conceptualization: Y. Li, X. Zhang, Z. Zhang and H. Jia, Writing\u0026mdash;original draft: X. Zhang and X. Zhao, Writing\u0026mdash;review \u0026amp; editing: Z. Zhang and C.Y. Zhang.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e\u003cp\u003eThe authors greatly acknowledge the Key Research and Development Program of the Ministry of Science and Technology [2023YFA0914300 (2023YFA0914304)], fund from Shanghai Jahwa United Co., Ltd., National Natural Science Foundation of China (22278242), Guangdong Innovative and Entrepreneurial Research Team Program (2023ZT10C040), Shenzhen Technology and Innovation Commission (KCXFZ20230731094459001, KCXFZ20240903093102004), Shenzhen International Graduate School at Tsinghua University (HW2023009, JC2021011).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eTuchayi, S. M. \u003cem\u003eet al.\u003c/em\u003e Acne vulgaris. \u003cem\u003eNature Reviews Disease Primers\u003c/em\u003e 1, 15029 (2015).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRajput, I. \u0026amp; Anjankar, V. P. 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Insertion of microneedles into skin: Measurement and prediction of insertion force and needle fracture force. \u003cem\u003eJournal of Biomechanics\u003c/em\u003e 37, 1155\u0026ndash;1163 (2004).\u003c/span\u003e\u003c/li\u003e\u003c/ol\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":"microsystems-and-nanoengineering","isNatureJournal":false,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"micronano","sideBox":"Learn more about [Microsystems \u0026 Nanoengineering](http://www.nature.com/micronano/)","snPcode":"41378","submissionUrl":"https://mts-micronano.nature.com/","title":"Microsystems \u0026 Nanoengineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Dissolved microneedle, Bubble structure, Drug delivery, Acne vulgaris therapy, Antimicrobial activity","lastPublishedDoi":"10.21203/rs.3.rs-7269052/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7269052/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eAcne vulgaris, a prevalent inflammatory skin disorder, poses significant clinical challenges due to its multifactorial pathogenesis involving \u003cem\u003eP. acnes\u003c/em\u003e proliferation and chronic inflammation. Conventional therapies, including topical applications, oral medication, and laser treatments, face limitations in drug penetration, patient compliance, and therapy efficacy. Currently, the combined use of hydrophilic drugs and hydrophobic drugs is a commonly recommended clinical approach. However, conventional formulations struggle to effectively deliver and release both therapeutic agents synergistically at the affected site. To address these issues, we developed a kind of dissolved bubble microneedle patches (DBMNPs) for the co-delivery of hydrophilic (dipotassium glycyrrhizinate, DPG), hydrophobic (PIONIN) drugs, and alongside salicylic acid (SA) in a base layer. The DBMNPs, fabricated based on hyaluronic acid (HA), feature hollow bubble structures to encapsulate lipophilic agents, enabling spatially segregated and temporally controlled drug release. The patches exhibit good mechanical strength, excellent biocompatibility, and potent antimicrobial activity against \u003cem\u003eP. acnes\u003c/em\u003e. \u003cem\u003eIn vivo\u003c/em\u003e studies confirmed their efficacy in treating acne vulgaris, offering a minimally invasive and clinically translatable approach to enhance therapeutic effect while minimizing systemic side effects. This study developed a MN platform that successfully addresses the key challenge of co-loading and co-delivering both hydrophilic and hydrophobic drugs, and are expected to be applied in the treatment of other diseases.\u003c/p\u003e","manuscriptTitle":"Dissolved Bubble Microneedle Patches for Co-Delivery of Hydrophobic and Hydrophilic Drugs to Improve Acne Vulgaris Therapy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-07 06:51:41","doi":"10.21203/rs.3.rs-7269052/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"revise","date":"2025-08-28T01:19:51+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"This content is not available.","date":"2025-08-25T04:50:16+00:00","index":1,"fulltext":"This content is not available."},{"type":"editorInvitedReview","content":"This content is not available.","date":"2025-08-23T22:13:40+00:00","index":2,"fulltext":"This content is not available."},{"type":"editorInvitedReview","content":"This content is not available.","date":"2025-08-19T07:22:50+00:00","index":3,"fulltext":"This content is not available."},{"type":"reviewerAgreed","content":"This content is not available.","date":"2025-08-13T02:44:51+00:00","index":3,"fulltext":"This content is not available."},{"type":"reviewerAgreed","content":"This content is not available.","date":"2025-08-05T22:13:04+00:00","index":2,"fulltext":"This content is not available."},{"type":"reviewerAgreed","content":"This content is not available.","date":"2025-08-04T18:29:22+00:00","index":1,"fulltext":"This content is not available."},{"type":"reviewersInvited","content":"","date":"2025-08-04T11:07:45+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-04T07:57:42+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-01T08:23:27+00:00","index":"","fulltext":""},{"type":"submitted","content":"Microsystems \u0026 Nanoengineering","date":"2025-08-01T08:23:26+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"microsystems-and-nanoengineering","isNatureJournal":false,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"micronano","sideBox":"Learn more about [Microsystems \u0026 Nanoengineering](http://www.nature.com/micronano/)","snPcode":"41378","submissionUrl":"https://mts-micronano.nature.com/","title":"Microsystems \u0026 Nanoengineering","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b2d9085a-1425-4cf5-959d-5b28f135ca3e","owner":[],"postedDate":"August 7th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":52604866,"name":"Physical sciences/Engineering"},{"id":52604867,"name":"Physical sciences/Materials science"}],"tags":[],"updatedAt":"2025-11-25T08:17:48+00:00","versionOfRecord":{"articleIdentity":"rs-7269052","link":"https://doi.org/10.1038/s41378-025-01079-y","journal":{"identity":"microsystems-and-nanoengineering","isVorOnly":false,"title":"Microsystems \u0026 Nanoengineering"},"publishedOn":"2025-11-24 05:00:00","publishedOnDateReadable":"November 24th, 2025"},"versionCreatedAt":"2025-08-07 06:51:41","video":"","vorDoi":"10.1038/s41378-025-01079-y","vorDoiUrl":"https://doi.org/10.1038/s41378-025-01079-y","workflowStages":[]},"version":"v1","identity":"rs-7269052","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7269052","identity":"rs-7269052","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}