Microneedle System with Biomarker-Activatable Chromophore as Both Optical Imaging Probe and Anti-bacterial Agent for Combination Therapy of Bacterial-Infected Wounds and Outcome Monitoring

Wounds infected with bacteria, if left untreated, have the potential to escalate into life-threatening conditions, such as sepsis, which is characterized by widespread inflammation and organ damage. A comprehensive approach to treating bacterial-infected wounds, encompassing the control of bacterial infection, biofilm eradication, and inflammation regulation, holds significant importance. Herein, a microneedle (MN) patch (FM@ST MN) has been developed, with silk fibroin (SF) and tannic acid-based hydrogel serving as the matrix. Encapsulated within the MNs are the AIEgen-based activatable probe (FQ-H2O2) and the NLRP3 inhibitor MCC950, serving as the optical reporter/antibacterial agent and the inflammation regulator, respectively. When applied onto bacterial-infected wounds, the MNs in FM@ST MN penetrate bacterial biofilms and gradually degrade, releasing FQ-H2O2 and MCC950. The released FQ-H2O2 responds to endogenously overexpressed reactive oxygen species (H2O2) at the wound site, generating a chromophore FQ-OH which emits noticeable NIR-II fluorescence and optoacoustic signals, enabling real-time imaging for outcome monitoring; and this chromophore also exhibits potent antibacterial capability due to its dual positive charges and shows negligible antibacterial resistance. However, the NLRP3 inhibitor MCC950, upon release, suppresses the activation of NLRP3 inflammasomes, thereby mitigating the inflammation triggered by bacterial infections and facilitating wound healing. Furthermore, SF in FM@ST MN aids in tissue repair and regeneration by promoting the proliferation of epidermal cells and fibroblasts and collagen synthesis. This MN system, free from antibiotics, holds promise as a solution for treating and monitoring bacterially infected wounds without the associated risk of antimicrobial resistance.

Self-Heating Multistage Microneedle Patch for Topical Therapy of Skin Cancer

Topical therapy is a favored route for treating skin cancers, but remain many challenges, such as low delivery efficiency, limited tumor tissue penetration, and unsatisfactory blood circulation. Here, a self-heating microneedle (MN) patch with multilevel structures, including a dissolvable base for rapid drug release, a degradable tip for sustained drug release, and a self-heating substrate is described. The thermally enhanced drug release performance is validated through both in vitro and in vivo experiments. High tumor therapeutic efficacy can be achieved due to the rapid release of 5-fluorouracil, while the sustained release of thymoquinone endows the MN patch with long-term tumor inhibition ability. It is further demonstrated the feasibility of such an MN patch for in vivo topical therapy of cutaneous squamous cell carcinoma with high efficacy, low side effects, and long-term inhibition of recurrence. This self-heating MN patch holds great promise for potential clinical applications, especially for the treatment of skin cancers.

CFD simulation of cannabidiol delivery through microneedle patches

This study investigates the efficiency and influence of microneedle parameters, specifically Needle Point Angle (a) and Needle Height (h), on the diffusion of Cannabidiol (CBD) across varying skin depths. Utilizing the Latin Hypercube Sampling method, twelve distinct cases were analyzed. Observations reveal a consistent high concentration of CBD delivered via the microneedle patch, with a notable decrease in concentration as the depth increases, displaying a non-linear trend. Multivariate polynomial regression offers a quantitative relationship between the variables, with the third-order bivariate fitting providing the most accurate representation. Compared to other CBD delivery mechanisms, microneedle patches present enhanced CBD concentrations, circumventing challenges faced by other methods such as dosage inaccuracy, systemic absorption issues, and CBD degradation. The results highlight the potential of microneedle patches as a promising avenue for optimized transdermal drug delivery.

All-in-One Self-Powered Microneedle Device for Accelerating Infected Diabetic Wound Repair

Diabetic wound healing remains a significant clinical challenge due to the complex microenvironment and attenuated endogenous electric field. Herein, a novel all-in-one self-powered microneedle device (termed TZ@mMN-TENG) is developed by combining the multifunctional microneedle carried tannin@ZnO microparticles (TZ@mMN) with the self-powered triboelectric nanogenerator (TENG). In addition to the delivery of tannin and Zn2+ , TZ@mMN also effectively conducts electrical stimulation (ES) to infected diabetic wounds. As a self-powered device, the TENG can convert biomechanical motion into exogenous ES to accelerate the infected diabetic wound healing. In vitro experiment demonstrated that TZ@mMN shows excellent conductive, high antioxidant ability, and effective antibacterial properties against both Staphylococcus aureus and Escherichia coli (>99% antibacterial rates). Besides, the TZ@mMN-TENG can effectively promote cell proliferation and migration. In the diabetic rat full-thickness skin wound model infected with Staphylococcus aureus, the TZ@mMN-TENG can eliminate bacteria, accelerate epidermal growth (regenerative epidermis: ≈303.3 ± 19.1 µm), enhance collagen deposition, inhibit inflammation (lower TNF-α and IL-6 expression), and promote angiogenesis (higher CD31 and VEGF expression) to accelerate infected wound repair. Overall, the TZ@mMN-TENG provides a promising strategy for clinical application in diabetic wound repair.

Turning Threat to Therapy: A Nanozyme-Patch in Surgical Bed for Convenient Tumor Vaccination by Sustained In-Situ Catalysis

Complete surgical resection of tumor is difficult as the invasiveness of cancer, making the residual tumor a lethal threat to patients. The situation is deteriorated by the immune suppression state after surgery, which further nourishes tumor recurrence and metastasis. Immunotherapy is promising to combat tumor metastasis, but is limited by severe toxicity of traditional immunostimulants and complexity of multiple functional units. Here, we report that the simple "trans-surgical bed" delivery of Cu2-x Se nanozyme (CSN) by a microneedle-patch can turn the threat to therapy by efficient in situ vaccination. The biocompatible CSN exhibited both peroxidase and glutathione oxidase-like activities, efficiently exhausting glutathione, boosting free radical generation, and inducing immunogenic cell death. The once-for-all inserting of the patch on surgical bed facilitates sustained catalytic action, leading to drastic decrease of recurrence rate and complete suppression of tumor-rechallenge in cured mice. In vivo mechanism interrogation reveals elevated cytotoxic T cell infiltration, re-educated macrophages, increased dendritic cell maturation, and memory T cells formation. Importantly, preliminary metabolism and safety evaluation validated that the metal accumulation is marginable, and the important biochemical indexes are in normal range during therapy. This study has provided a simple, safe, and robust tumor vaccination approach for post-surgical metastasis control. This article is protected by copyright. All rights reserved.

Electrostatic-Interaction-Aided Microneedle Patch for Enhanced Glucose-Responsive Insulin Delivery and Three-Meal-Per-Day Blood-Glucose Regulation

The phenylborate-ester-cross-linked hydrogel microneedle patch (MNP) was promising in the diabetic field for the glucose-responsive insulin-delivering property and simple fabrication process. However, the unfit design of the charging microneedle network limited the improvement of blood-glucose regulating performances. In this work, insulin-loaded phenylborate-ester-cross-linked MNPs, with the polyzwitterion property, were constructed based on the modified ε-polylysine and poly(vinyl alcohol). The relationship between the charging nature of the MNP network and insulin release was verified by regulating the content of postprotonated positively charged amino groups. The elaborately designed MNP possessed improved glucose-responsive insulin-delivering performance. The in vivo study revealed the satisfactory results on blood-glucose regulation by the optimized MNP under the mimic three-meal-per-day mode. Moreover, the insulin bioactivity in the MNP could be maintained for 2 weeks under 25 °C. In summary, this work developed an effective strategy to improve the glucose-responsive phenylborate-ester-cross-linked MNP and enhance its potential for clinical transformation.

In Vitro Release of Glycyrrhiza Glabra Extract by a Gel-Based Microneedle Patch for Psoriasis Treatment

Microneedle patches are attractive drug delivery systems that give hope for treating skin disorders. In this study, to first fabricate a chitosan-based low-cost microneedle patch (MNP) using a CO2 laser cutter for in vitro purposes was tried and then the delivery and impact of Glycyrrhiza glabra extract (GgE) on the cell population by this microneedle was evaluated. Microscopic analysis, swelling, penetration, degradation, biocompatibility, and drug delivery were carried out to assess the patch's performance. DAPI staining and acridine orange (AO) staining were performed to evaluate cell numbers. Based on the results, the MNs were conical and sharp enough (diameter: 400-500 μm, height: 700-900 μm). They showed notable swelling (2 folds) during 5 min and good degradability during 30 min, which can be considered a burst release. The MNP showed no cytotoxicity against fibroblast cell line L929. It also demonstrated good potential for GgE delivery. The results from AO and DAPI staining approved the reduction in the cell population after GgE delivery. To sum up, the fabricated MNP can be a useful recommendation for lab-scale studies. In addition, a GgE-loaded MNP can be a good remedy for skin disorders in which cell proliferation needs to be controlled.

It Takes Two to Tangle: Microneedle Patches Co-delivering Monoclonal Antibodies and Engineered Antimicrobial Peptides Effectively Eradicate Wound Biofilms

Wound biofilms pose a great clinical challenge. Herein, this work reports a dissolvable microneedle patch for dual delivery of monoclonal antibodies anti-PBP2a and engineers antimicrobial peptides W379. In vitro antibacterial efficacy testing with microneedle patches containing a combination of 250 ng mL-1 W379 and 250 ng mL-1 anti-BPB2a decreases the bacterial count from ≈3.31 × 107 CFU mL-1 to 1.28 × 102 CFU mL-1 within 2 h without eliciting evident cytotoxicity. Ex vivo testing indicates W379 and anti-PBP2a co-loaded microneedle patch displayed a remarkable reduction of bacterial load by ≈7.18 log CFU after administered only once within 48 h. The bacterial count is significantly diminished compared to the treatment by either W379 or anti-PBP2a-loaded alone microneedle patches. When administered twice within 48 h, no bacteria are identified. Further in vivo study also reveals that after two treatments of W379 and anti-PBP2a co-loaded PVP microneedle patches within 48 h, the bacterial colonies are undetectable in a type II diabetic mouse wound biofilm model. Taken together, W379 and anti-PBP2a co-loaded PVP microneedle patches hold great promise in treating wound biofilms.

Antilipogenesis Effect of Rutin-Loaded Liposomes Using a Microneedle Delivery System

Rutin, a flavonoid glycoside phytochemical compound, has a remarkable antiobesity effect. However, its therapeutic potential is hindered by its poor water solubility and low oral bioavailability. In this study, rutin was loaded into liposomes (LR) through the self-assembly of lecithin and cholesterol. It was discovered that liposomes improved the water solubility and cellular uptake of rutin in adipocytes. These rutin-loaded liposomes were then incorporated into a microneedle patch (MP) system formed by polyvinylpyrrolidone and poly(vinyl alcohol), and the MP-LR showed an increased release percentage in the adipose tissue microenvironment of pH 6.5 and achieved local delivery of rutin into adipocytes. Next, the therapeutic potentials of rutin, LR, and MP-LR were investigated in a high-fat diet (HFD)-induced obese mouse model. The MP-LR formulation decreased the weight of the HFD mice the most significantly. The antilipogenesis mechanisms of MP-LR are downregulating the lipid synthesis-related proteins (PPAR γ and C/EBP α) in adipocytes and promoting the expression of the beige adipogenesis-related proteins (UCP 1 and Cyt C). The MP systems further promote the local penetration of LR into the adipose tissue specifically, which again elevates their antiobesity effect. Overall, this study suggests that MP-delivered liposome-based formulation is a promising approach to enhance the antiobesity efficacy of antilipogenesis bioactive compounds.

In Situ Tyrosinase Monitoring by Wearable Microneedle Patch toward Clinical Melanoma Screening

Despite the potential indicating role of tyrosinase (TYR) in cutaneous melanoma, how to capture the real changes of TYR in suspicious skin remains a major challenge. Unlike the traditional human serum test, this study reports a sensing platform that incorporates a wearable microneedle (MN) patch and trimetallic Au@Ag-Pt nanoparticles (NPs) for surface-enhanced Raman scattering (SERS) and colorimetric dual-mode detecting TYR in human skin in situ toward potential melanoma screening. In the presence of TYR, catechol immobilized on MN is preferentially oxidized to benzoquinone, which competitively impedes the interaction of MN and Au@Ag-Pt NPs, triggering the SERS-colorimetric signal reciprocal switch. Using a B16F10 mouse melanoma model, our platform is capable of noninvasively piercing the skin surface and detecting TYR levels before and during anti-PD-1 antibody treatment, which would be highly informative for prognostic judgment and illness monitoring of melanoma. Through in situ sensing for capturing the metabolic changes of TYR in advance, this platform was successfully applied to discriminate the melanoma subjects from skin moles and normal ones (p < 0.001), as well as screen potential melanoma from lactate dehydrogenase (LDH)-negative patients. Melanoma growth and prognosis can still be monitored through recording the continuous change of TYR levels. More importantly, the well-defined flexible and stretchable characteristics of the MN patch allow robustly adhering to the skin without inducing chemical or physical irritation. We believe this platform integrating MN-based in situ sensing, TYR responsiveness, and SERS/colorimetric dual-readout strategy will have high clinical importance in early diagnosis and monitoring of cutaneous melanoma.

Layer-Specific BTX-A Delivery to the Gastric Muscularis Achieves Effective Weight Control and Metabolic Improvement

The rising incidence of health-endangering obesity constantly calls for more effective treatments. Gastric intramural injection of botulinum neurotoxin A (BTX-A) as a new modality carries great promise yet inconsistent therapeutic efficacy. A layer-specific delivery strategy enabled by dissolving microneedles is hence pioneered to investigate the working site of BTX-A and the resulting therapeutic effects. The drug-loaded tips of the layer-specific gastric paralysis microneedles (LGP-MN) rapidly release and achieve uniform distribution of BTX-A within the designated gastric wall layers. In an obesity rat model, the LGP-MNs not only prove safer than conventional injection, but also demonstrate consistently better therapeutic effects with muscular layer delivery, including 16.23% weight loss (3.06-fold enhancement from conventional injection), 55.20% slower gastric emptying rate, improved liver steatosis, lowered blood lipids, and healthier gut microbiota. Further hormonal study reveals that the elevated production of stomach-derived glucagon-like peptide-1 due to the muscularis-targeting LGP-MN treatment is an important contributor to its unique glucose tolerance-improving effect. This study provides clear indication of the gastric muscularis as the most favorable working site of BTX-A for weight loss and metabolic improvement purposes, and meanwhile suggests that the LGP-MNs could serve as a novel clinical approach to treat obesity and metabolic syndromes.

Developing an efficient MGCR microneedle nanovaccine patch for eliciting Th 1 cellular response against the SARS-CoV-2 infection

Rationale: Novel vaccine R&D is essential to interrupt the COVID-19 pandemic and other epidemics in the future. Subunit vaccines have received tremendous attention for their low cost and safety. To improve the immunogenicity of subunit vaccines, we developed a novel vaccine adjuvant system. Methods: Here we rationally designed a CpG 1018 and graphene oxide-based bi-adjuvant system to deliver the Receptor-Binding Domain (RBD) of the SARS-CoV-2 spike protein and obtained the graphene oxide-based complex adjuvant nanovaccine (GCR). Furthermore, we developed a microneedle patch vaccine (MGCR) based on the GCR vaccine. Results: GCR nanovaccine displayed superb antigen loading and encapsulation efficiency. Two dosages of vaccination of GCR nanovaccine could elicit adequate RBD-specific binding antibody response with 2.14-fold higher IgG titer than Alum adjuvant vaccine. The peptide pools assay demonstrated the robust RBD-specific Type 1 Cellular response induced by the GCR nanovaccine in CD8+ T cells. Furthermore, we prepared an MGCR microneedle patch, which generated a similar RBD-specific binding antibody response to the GCR vaccine, sustained a high antibody level above 16 weeks, and significantly elevated the Tcm proportion in mouse spleen. The MGCR microneedle patch vaccine also could be stably stored at room temperature for several months and administrated without medical staff, which maximizes the vaccine distribution efficiency. Conclusion: The vaccine system could significantly improve the vaccine distribution rate in low-income areas and offer a potential vaccination approach to fight against the SARS-Cov-2 infection and other pandemics occurred in the future.

Molecular Docking-Guided Design on Glucose-Responsive Nanoparticles for Microneedle Fabrication and "Three-Meal-per-Day" Blood-Glucose Regulation

It was greatly significant, but difficult, to develop stimulus-responsive polymeric nanoparticles with efficient protein-loading and protein-delivering properties. Crucial obstacles were the ambiguous protein/nanoparticle-interacting mechanisms and the corresponding inefficient trial-and-error strategies, which brought large quantities of experiments in design and optimization. In this work, a molecular docking-guided universal "segment-functional group-polymer" process was proposed to simplify the previous laborious experimental step. The insulin-delivering glucose-responsive polymeric nanoparticles for diabetic treatments were taken as the examples. The molecular docking study obtained insights from the insulin/segment interactions. It was then experimentally confirmed in six functional groups for insulin-loading performances of their corresponding polymers. The optimization formulation was further proved effective in blood-glucose stabilization on the diabetic rats under the "three-meal-per-day" mode. It was believed that the molecular docking-guided designing process was promising in the protein-delivering field.

Protection against tuberculosis achieved by dissolving microneedle patches loaded with live Mycobacterium paragordonae in a BCG prime-boost strategy

Introduction

Skin vaccination using dissolving microneedle patch (MNP) technology for transdermal delivery is a promising vaccine delivery strategy to overcome the limitations of the existing vaccine administration strategies using syringes. To improve the traditional microneedle mold fabrication technique, we introduced droplet extension (DEN) to reduce drug loss. Tuberculosis remains a major public health problem worldwide, and BCG revaccination had failed to increase the protective efficacy against tuberculosis. We developed an MNP with live Mycobacterium paragordonae (Mpg) (Mpg-MNP) as a candidate of tuberculosis booster vaccine in a heterologous prime-boost strategy to increase the BCG vaccine efficacy.

Materials and methods

The MNPs were fabricated by the DEN method on a polyvinyl alcohol mask film and hydrocolloid-adhesive sheet with microneedles composed of a mixture of mycobacteria and hyaluronic acid. We assessed the transdermal delivery efficiency by comparing the activation of the dermal immune system with that of subcutaneous injection. A BCG prime Mpg-MNP boost regimen was administered to a mouse model to evaluate the protective efficacy against M. tuberculosis.

Results

We demonstrated the successful transdermal delivery achieved by Mpg-MNP compared with that observed with BCG-MNP or subcutaneous vaccination via an increased abundance of MHCII-expressing Langerin+ cells within the dermis that could migrate into draining lymph nodes to induce T-cell activation. In a BCG prime-boost regimen, Mpg-MNP was more protective than BCG-only immunization or BCG-MNP boost, resulting in a lower bacterial burden in the lungs of mice infected with virulent M. tuberculosis. Mpg-MNP-boosted mice showed higher serum levels of IgG than BCG-MNP-boosted mice. Furthermore, Ag85B-specific T-cells were activated after BCG priming and Mpg-MNP boost, indicating increased production of Th1-related cytokines in response to M. tuberculosis challenge, which is correlated with enhanced protective efficacy.

Discussion

The MNP fabricated by the DEN method maintained the viability of Mpg and achieved effective release in the dermis. Our data demonstrate a potential application of Mpg-MNP as a booster vaccine to enhance the efficacy of BCG vaccination against M. tuberculosis. This study produced the first MNP loaded with nontuberculous mycobacteria (NTM) to be used as a heterologous booster vaccine with verified protective efficacy against M. tuberculosis.

Microneedle Patch Delivery of PROTACs for Anti-Cancer Therapy

Proteolysis-targeting chimera (PROTAC) is an emerging technique for degrading disease-related proteins. However, the current PROTACs suffer from inadequate solubility and lack of organ targeting, which has hampered their druggability. Herein, we report direct and sustained delivery of PROTACs using microneedle patches to the diseased tissues. In this study, we use an estrogen receptor alpha (ERα)-degrading PROTAC, ERD308, to treat ER-positive breast cancer. A pH-sensitive micelle, MPEG-poly(β-amino ester) (MPEG-PAE), is used to encapsulate ERD308 along with an FDA-approved CDK4/6 inhibitor, Palbociclib (Pal), before loading into biodegradable microneedle patches. These patches enable prolonged drug release into deep tumors, maintaining therapeutic levels for at least 4 days, with an excellent drug retention rate of over 87% in tumors. ERD308 released from the microneedle patches can sufficiently degrade ERα in MCF7 cells. Co-administration of ERD308 and Palbociclib exhibits excellent efficacy by over 80% tumor reduction as well as a good safety profile. Our work demonstrates the feasibility and proof-of-concept therapeutic potential of using microneedle patches to directly deliver PROTACs into tumors.

Dissolving Microneedle Patch Integrated with Microspheres for Long-Acting Hair Regrowth Therapy

Androgenetic alopecia (AGA) is the most common type of progressive hair loss in both men and women that severely reduces life quality and affects patients' self-esteem. Due to the shortcomings of traditional therapeutic formulations (e.g., topical minoxidil and oral finasteride), such as low bioavailability, frequent dosing, and significant side effects, there is an urgent need to develop a safe and effective strategy for AGA treatment. Here, we report a water-soluble microneedle (MN) patch integrated with biodegradable minoxidil (MXD)-loaded microspheres for long-acting AGA treatment with reduced administration frequency and improved patient compliance. When the patch pierces the skin, the MNs rapidly dissolve and deliver MXD-encapsulated polylactic-co-glycolic acid (PLGA) microspheres into the skin, which, subsequently act as drug reservoirs for the sustained release of the therapeutics for over 2 weeks. Additionally, the application of the MN patch provided a mechanical stimulation on mouse skin, which was also helpful for hair regrowth. Compared with the topical MXD solutions that have been commercialized on the market and require daily application, the long-acting MN patch contains a much lower drug amount and shows a similar or superior hair regeneration effect in AGA mice while only requiring monthly or weekly administration. These encouraging results suggest a simple, safe, and effective strategy for long-acting hair regeneration in clinics.

Novel Microneedle Patch-Based Surface-Enhanced Raman Spectroscopy Sensor for the Detection of Pesticide Residues

Pesticide residues are a global threat to human health, and conventional sensors fail to simultaneously detect pesticide residues on the surface and inside agricultural products. In this work, we present a new microneedle (MN) patch-based surface-enhanced Raman spectroscopy (SERS) sensor. The needles and the basement of MNs can simultaneously detect pesticide residues on the surface and inside agricultural products. The Ag nanoparticles and sodium hyaluronate/poly(vinyl alcohol) (HA/PVA) hydrogel used in this MN patch-based sensor efficiently amplify the Raman signals of the pesticide residues. In addition, the HA/PVA hydrogel can effectively and quickly collect the residues, allowing this sensor to detect pesticide residues more conveniently. Furthermore, the stepped structure of the MNs increases the sensor's surface area. Experimental results show that the sensor can detect thiram and thiabendazole (TBZ) pesticide residues with detection limits of 10^-7 and 10^-8 M, respectively. The detection process is minimally invasive and not harmful to agricultural products. The application of this MN patch-based SERS sensor can be extended to the safety and health monitoring of other plants and animals.

Microarray patch for HIV prevention and as a multipurpose prevention technology to prevent HIV and unplanned pregnancy: an assessment of potential acceptability, usability, and programmatic fit in Kenya

Background

Microarray patches (MAPs), a novel drug delivery system, are being developed for HIV pre-exposure prophylaxis (PrEP) delivery and as a multipurpose prevention technology (MPT) to protect from both HIV and unintended pregnancy. Prevention technologies must meet the needs of target audiences, be acceptable, easy to use, and fit health system requirements.

Methodology

We explored perceptions about MAP technology and assessed usability, hypothetical acceptability, and potential programmatic fit of MAP prototypes using focus group discussions (FGD), usability exercises, and key informant interviews (KII) among key populations in Kiambu County, Kenya. Adolescent girls and young women (AGYW), female sex workers (FSW), and men who have sex with men (MSM) assessed the usability and acceptability of a MAP prototype. Male partners of AGYW/FSW assessed MAP acceptability as partners of likely users. We analyzed data using NVivo, applying an inductive approach. Health service providers and policymakers assessed programmatic fit. Usability exercise participants applied a no-drug, no-microneedle MAP prototype and assessed MAP features.

Results

We implemented 10 FGD (4 AGYW; 2 FSW; 2 MSM; 2 male partners); 47 mock use exercises (19 AGYW; 9 FSW; 8 MSM; 11 HSP); and 6 policymaker KII. Participants reported high interest in MAPs due to discreet and easy use, long-term protection, and potential for self-administration. MAP size and duration of protection were key characteristics influencing acceptability. Most AGYW preferred the MPT MAP over an HIV PrEP-only MAP. FSW saw value in both MAP indications and voiced need for MPTs that protect from other infections. Preferred duration of protection was 1-3 months. Some participants would accept a larger MAP if it provided longer protection. Participants suggested revisions to the feedback indicator to improve confidence. Policymakers described the MPT MAP as "killing two birds with one stone," in addressing AGYW needs for both HIV protection and contraception. An MPT MAP is aligned with Kenya's policy of integrating health care programs.

Conclusions

MAPs for HIV PrEP and as an MPT both were acceptable across participant groups. Some groups valued an MPT MAP over an HIV PrEP MAP. Prototype refinements will improve usability and confidence.

Skin Vaccination with Ebola Virus Glycoprotein Using a Polyphosphazene-Based Microneedle Patch Protects Mice against Lethal Challenge

Ebolavirus (EBOV) infection in humans is a severe and often fatal disease, which demands effective interventional strategies for its prevention and treatment. The available vaccines, which are authorized under exceptional circumstances, use viral vector platforms and have serious disadvantages, such as difficulties in adapting to new virus variants, reliance on cold chain supply networks, and administration by hypodermic injection. Microneedle (MN) patches, which are made of an array of micron-scale, solid needles that painlessly penetrate into the upper layers of the skin and dissolve to deliver vaccines intradermally, simplify vaccination and can thereby increase vaccine access, especially in resource-constrained or emergency settings. The present study describes a novel MN technology, which combines EBOV glycoprotein (GP) antigen with a polyphosphazene-based immunoadjuvant and vaccine delivery system (poly[di(carboxylatophenoxy)phosphazene], PCPP). The protein-stabilizing effect of PCPP in the microfabrication process enabled preparation of a dissolvable EBOV GP MN patch vaccine with superior antigenicity compared to a non-polyphosphazene polymer-based analog. Intradermal immunization of mice with polyphosphazene-based MN patches induced strong, long-lasting antibody responses against EBOV GP, which was comparable to intramuscular injection. Moreover, mice vaccinated with the MN patches were completely protected against a lethal challenge using mouse-adapted EBOV and had no histologic lesions associated with ebolavirus disease.

Pharmacokinetic improvement provided by microneedle patch in delivering bee venom, a case study in combating scopolamine-induced neurodegeneration in mouse model

Much research has shown Bee venom to be an effective neuroprotective agent. However, the usual transdermal injection of bee venom poses many pharmacokinetic disadvantages. Here, we compared the administration of bee venom via subcutaneous injection (SC) and via Microneedle patch (MN). Both administrated routes produce significant recovery effects, however: the MN significantly prolongs the bio-significant-and-yet-lower concentration of bee venom in mice bodies. In contrast, SC could produce only a short period of much higher bee venom levels in the blood and brain. We also see that due to the concentration-response-curve of bee venom (represented by melittin): mice bodies do not require much higher bee venom concentration (seen in the SC group) to produce a much more significant neuroprotective effect (than seen in those treated with the MN method). Therefore, a MN could maintain bee venom levels in mice bodies at lower-yet-more-efficient concentrations. This is important, as bee venom can cause more adverse effects and pain sensations, at higher concentrations. For the first time, we confirmed that the pharmacokinetic advantages of MN delivered bee venom also guarantee a holistic neuroprotection effect (which was shown by SC delivered bee venom in previous research). This was proven via the results of the water maze experiments for long-term learning memory assessment and protein analysis of key neuronal regulatory proteins: BDNF, p-CREB, iNOS, and mArhR 1. In conclusion, for situations where we ought to administrate drugs at a more downward amount, such as bee venom, MN can keep the therapeutic concentrations at a lower, yet interestingly, more-efficient level.

Detachable Microneedle Patches Deliver Mesenchymal Stromal Cell Factor-Loaded Nanoparticles for Cardiac Repair

Intramyocardial injection is a direct and efficient approach to deliver therapeutics to the heart. However, the injected volume must be very limited, and there is injury to the injection site and leakage issues during heart beating. Herein, we developed a detachable therapeutic microneedle (MN) patch, which is comprised of mesenchymal stromal cell-secreted factors (MSCF)-loaded poly(lactic-co-glycolic acid) nanoparticles (NP) in MN tips made of elastin-like polypeptide gel, with a resolvable non-cross-linked hyaluronic acid (HA) gel as the MN base. The tips can be firmly inserted into the infarcted myocardium after base removal, and no suture is needed. In isolated neonatal rat cardiac cells, we found that the cellular uptake of MSCF-NP in the cardiomyocytes was higher than in cardiac fibroblasts. MSCF-NP promoted the proliferation of injured cardiomyocytes. In a rat model of myocardial infarction, MN-MSCF-NP treatment reduced cardiomyocyte apoptosis, restored myocardium volume, and reduced fibrosis during the cardiac remodeling process. Our work demonstrated the therapeutic potential of MN to deliver MSCF directly into the myocardium and provides a promising treatment approach for cardiac diseases.

A Microneedle Patch with Self-Oxygenation and Glutathione Depletion for Repeatable Photodynamic Therapy

Photodynamic therapy (PDT) has attained extensive attention as a noninvasive tumor treatment modality. However, the hypoxia in solid tumors, skin phototoxicity of "always on" photosensitizers (PSs), and abundant supply of glutathione (GSH) in cancer cells severely hampered the clinical applications of PDT. Herein, a self-oxygenation nanoplatform (denoted as CZCH) with GSH depletion ability was encapsulated into the hyaluronic acid microneedle patch (MN-CZCH) to simultaneously improve the biosafety and therapeutic efficacy of PDT. The Cu²⁺-doped porous zeolitic imidazolate framework incorporated with catalase (CAT) is capable of efficiently loading PS 2-(1-hexyloxyethyl)-2-divinylpyropheophorbic-a (HPPH). The CZCH intermingled MN patch (MN-CZCH) could effectively penetrate the stratum corneum, topically transport HPPH to the target tumor site, achieve a long tumor retention time, and enhance the efficacy of PDT via the simultaneously synergistic effect of CAT-catalyzed self-supplying O₂ and Cu²⁺-mediated GSH depletion. Using traceable fluorescence (FL) imaging of the released HPPH from CZCH, the FL imaging-guided repeatable PDT can be achieved for enhanced antitumor efficacy. As a result, the MN-CZCH patch exhibited excellent therapeutic efficacy against melanoma with minimal toxicity, which has promising potential for cancer theranostics.

Galunisertib-Loaded Gelatin Methacryloyl Hydrogel Microneedle Patch for Cardiac Repair after Myocardial Infarction

Uncontrolled and excessive fibrosis after myocardial infarction (MI) in the peri-infarct zone leads to left ventricular remodeling and deterioration of cardiac function. Inhibiting fibroblast activation during the mature phase of cardiac repair improves cardiac remodeling and function after MI. Here, we engineered a biocompatible microneedle (MN) patch using gelatin methacryloyl and loaded it with galunisertib, a transforming growth factor-beta (TGF-β)-specific inhibitor, to treat excessive cardiac fibrosis after MI. The MN patch could sustainably release galunisertib for more than 2 weeks and provide mechanical support for the fragile ventricular wall. After being applied to a rat model of MI, the galunisertib-loaded MN patch improved long-term cardiac function and reduced cardiac fibrosis by effectively inhibiting TGF-β depending on fibroblast activation. This strategy shows the potential of the MN patch as an advanced platform to locally deliver direct antifibrotic drugs to prevent myocardial fibrosis for the treatment of MI and the promotion of cardiac repair.

Efficacy of a novel microneedle patch for rejuvenation of the nasolabial fold

BACKGROUND

Skin rejuvenation plays a significant role in the esthetic medicine market. Microneedle patches have been developed for a wide range of applications based on the principles of transdermal drug delivery; however, clinical trials of microneedle patches for skin rejuvenation remain limited.

AIMS

This study was conducted to examine the efficacy of microneedle patches for improving nasolabial folds.

METHODS

A total of 23 Thai women completed this prospective clinical trial. The participants were treated according to a split-face design, with application of microneedle patch plus 1.8% hyaluronic acid solution to the right nasolabial fold and microneedle patch alone to the left nasolabial fold. The treatments were applied to the nasolabial fold for 8 weeks. The test areas were measured before treatment and at 2, 4, 8, 12, and 16 weeks after the use of the test product.

RESULTS

Combination treatment using the microneedle patch plus hyaluronic acid solution and use of the microneedle patch alone both significantly improved the Merz esthetic scales for nasolabial folds. Measurement of the nasolabial fold showed an improvement in the two groups, with no significant differences between the groups. No adverse effects were reported during the study period.

CONCLUSIONS

Application of a microneedle patch with 1.8% hyaluronic acid solution or a microneedle patch alone were both effective treatments for improving facial wrinkles in the nasolabial folds.

Effect of Surface Interactions on Microsphere Loading in Dissolving Microneedle Patches

Microneedle (MN) patches enable simple self-administration of drugs via the skin. In this study, we sought to deliver drug-loaded microspheres (MSs) using MN patches and found that the poly(lactic-co-glycolic acid) (PLGA) MSs failed to localize in the MN tips during fabrication, thereby decreasing their delivered dose and delivery efficiency into skin. We determined that surface interactions between the hydrophobic MSs and the poly(dimethylsiloxane) (PDMS) mold caused MSs to adhere to the mold surface during casting in aqueous formulations, with hydrophobic interactions largely responsible for adhesion. Further studies with polystyrene MSs that similarly carry a negative charge like the PLGA MSs demonstrated both repulsive electrostatic interactions as well as adhesive hydrophobic interactions. Reducing hydrophobic interactions by addition of a surfactant or modifying mold surface properties increased MS loading into MN tips and delivery into porcine skin ex vivo by 3-fold. We conclude that surface interactions affect the loading of hydrophobic MSs into MN patches during aqueous fabrication procedures and that their modulation with the surfactant can increase loading and delivery efficiency.

Thermostability of Measles and Rubella Vaccines in a Microneedle Patch

Measles and rubella vaccinations are highly effective at reducing disease prevalence; however, logistic issues related to subcutaneous administration and vaccine wastage limit the extent of vaccination coverage. Microneedle (MN) patches can increase coverage by easing logistics through simplified administration and improved stability. This study demonstrates the thermostability of a bivalent measles and rubella vaccine MN patch. Rubella vaccine stability required pH buffering during drying; potassium phosphate buffer at neutral pH was optimal for both vaccines. Screening 43 excipients for their ability to retain potency during drying and storage yielded sucrose-threonine-potassium phosphate buffer formulation at pH 7.5 as an optimal formulation. MN patches made with this formulation had no significant loss of vaccine titer after one month and remained within a one log₁₀ titer loss cutoff after 3 - 4 months at 5°C, 25°C and 40°C. Finally, these patches were shown to be immunogenic in juvenile rhesus macaques. This work demonstrates the potential for MN patches for measles and rubella vaccination to be removed from the cold chain, which is expected to decrease vaccine cost and wastage, and increase vaccination coverage.

A Colorimetric Dermal Tattoo Biosensor Fabricated by Microneedle Patch for Multiplexed Detection of Health-Related Biomarkers

Detection of biomarkers associated with body conditions provides in-depth healthcare information and benefits to disease management, where the key challenge is to develop a minimally invasive platform with the ability to directly detect multiple biomarkers in body fluid. Dermal tattoo biosensor holds the potential to simultaneously detect multiple health-related biomarkers in skin interstitial fluid because of the features of minimal invasion, easy operation, and equipment-free result reading. Herein, a colorimetric dermal tattoo biosensor fabricated by a four-area segmented microneedle patch is developed for multiplexed detection of health-related biomarkers. The biosensor exhibits color changes in response to the change of biomarker concentration (i.e., pH, glucose, uric acid, and temperature), which can be directly read by naked eyes or captured by a camera for semi-quantitative measurement. It is demonstrated that the colorimetric dermal tattoo biosensor can simultaneously detect multiple biomarkers in vitro, ex vivo, and in vivo, and monitor the changes of the biomarker concentration for at least 4 days, showing its great potential for long-term health monitoring.

An overview on the advantages and limitations of 3D printing of microneedles

The use of 3D printing (3DP) technology, which has been continuously evolving since the 1980s, has recently become common in healthcare services. The introduction of 3DP into the pharmaceutical industry particularly aims at the development of patient-centered dosage forms based on structure design. It is still a new research direction with potential to create the targeted release of drug delivery systems in freeform geometries. Although the use of 3DP technology for solid oral dosage forms is more preferable, studies on transdermal applications of the technology are also increasing. Microneedle sequences are one of the transdermal drug delivery (TDD) methods which are used to bypass the minimally invasive stratum corneum with novel delivery methods for small molecule drugs and vaccines. Microneedle arrays have advantages over many traditional methods. It is attractive with features such as ease of application, controlled release of active substances and patient compliance. Recently, 3D printers have been used for the production of microneedle patches. After giving a brief overview of 3DP technology, this article includes the materials necessary for the preparation of microneedles and microneedle patches specifically for penetration enhancement, preparation methods, quality parameters, and their application to TDD. In addition, the applicability of 3D microneedles in the pharmaceutical industry has been evaluated.

Vancomycin-Loaded Microneedle Arrays against Methicillin-Resistant Staphylococcus Aureus Skin Infections

Skin and soft tissue infections (SSTIs) caused by methicillin-resistant Staphylococcus aureus (MRSA) are a major healthcare burden, often treated with intravenous injection of the glycopeptide antibiotic vancomycin (VAN). However, low local drug concentration in the skin limits its treatment efficiency, while systemic exposure promotes the development of resistant bacterial strains. Topical administration of VAN on skin is ineffective as its high molecular weight prohibits transdermal penetration. In order to implement a local VAN delivery, microneedle (MN) arrays with a water-insoluble support layer for the controlled administration of VAN into the skin are developed. The utilization of such a support layer results in water-insoluble needle shafts surrounded by drug-loaded water-soluble tips with high drug encapsulation. The developed MN arrays can penetrate the dermal barriers of both porcine and fresh human skin. Permeation studies on porcine skin reveal that the majority of the delivered VAN is retained within the skin. It is shown that the VAN-MN array reduces MRSA growth both in vitro and ex vivo on skin. The developed VAN-MN arrays may be extended to several drugs and may facilitate localized treatment of MRSA-caused skin infections while minimizing adverse systemic effects.

Instant and Multiple DNA Extraction Method by Microneedle Patch for Rapid and on-Site Detection of Food Allergen-Encoding Genes

DNA-based detection methods are highly promising for risk assessment in the food sector, such as tracing the existence of food allergens. However, due to the complexity of food matrices, cumbersome protocols are often needed to isolate the DNA components, which hinder the achievement of rapid and on-site detection. Herein, an instant and multiple DNA extraction method was developed based on the poly(vinyl alcohol) microneedle (MN) patch. With simple press and peel-off operations within 1 min, samples suitable for DNA-based analysis such as polymerase chain reaction (PCR) could be collected. By further combining with the recombinase polymerase amplification assay, rapid screening of the allergenic risks in complex samples such as shrimp ball and cheesecake could be achieved within 30 min. The MN-based DNA extraction method not only was a potential alternative to the traditional DNA extraction method but provided a transformative approach in realizing rapid, on-site detection of foodborne hazards in collaborating with fast DNA-based assays.

Dual self-regulated delivery of insulin and glucagon by a hybrid patch

Reduced β-cell function and insulin deficiency are hallmarks of diabetes mellitus, which is often accompanied by the malfunction of glucagon-secreting α-cells. While insulin therapy has been developed to treat insulin deficiency, the on-demand supplementation of glucagon for acute hypoglycemia treatment remains inadequate. Here, we describe a transdermal patch that mimics the inherent counterregulatory effects of β-cells and α-cells for blood glucose management by dynamically releasing insulin or glucagon. The two modules share a copolymerized matrix but comprise different ratios of the key monomers to be "dually responsive" to both hyper- and hypoglycemic conditions. In a type 1 diabetic mouse model, the hybrid patch effectively controls hyperglycemia while minimizing the occurrence of hypoglycemia in the setting of insulin therapy with simulated delayed meal or insulin overdose.

Influenza Vaccines toward Universality through Nanoplatforms and Given by Microneedle Patches

Influenza is one of the top threats to public health. The best strategy to prevent influenza is vaccination. Because of the antigenic changes in the major surface antigens of influenza viruses, current seasonal influenza vaccines need to be updated every year to match the circulating strains and are suboptimal for protection. Furthermore, seasonal vaccines do not protect against potential influenza pandemics. A universal influenza vaccine will eliminate the threat of both influenza epidemics and pandemics. Due to the massive challenge in realizing influenza vaccine universality, a single vaccine strategy cannot meet the need. A comprehensive approach that integrates advances in immunogen designs, vaccine and adjuvant nanoplatforms, and vaccine delivery and controlled release has the potential to achieve an effective universal influenza vaccine. This review will summarize the advances in the research and development of an affordable universal influenza vaccine.

DNA Extraction from Plant Leaves Using a Microneedle Patch

Isolation of high-quality DNA from infected plant specimens is an essential step for the molecular detection of plant pathogens. However, DNA isolation from plant cells surrounded by rigid polysaccharide cell walls involves complicated steps and requires benchtop laboratory equipment. As a result, plant DNA extraction is currently confined to well-equipped laboratories and sample preparation has become one of the major hurdles for on-site molecular detection of plant pathogens. To overcome this hurdle, a simple DNA extraction method from plant leaf tissues has been developed. A microneedle (MN) patch made of polyvinyl alcohol (PVA) can isolate plant or pathogenic DNA from different plant species within a minute. During DNA extraction, the polymeric MN patch penetrates into plant leaf tissues and breaks rigid plant cell walls to isolate intracellular DNA. The extracted DNA is polymerase chain reaction (PCR) amplifiable without additional purification. This minimally invasive method has successfully extracted Phytophthora infestans DNA from infected tomato leaves. Moreover, the MN patch could be used to isolate DNA from other plant pathogens directly in the field. Thus, it has great potential to become a rapid, on-site sample preparation technique for plant pathogen detection. © 2020 by John Wiley & Sons, Inc. Basic Protocol: Microneedle patch-based DNA extraction Support Protocol 1: Microneedle patch fabrication Support Protocol 2: Real-time PCR amplification of microneedle patch extracted DNA.

Feasibility of Hepatitis B Vaccination by Microneedle Patch: Cellular and Humoral Immunity Studies in Rhesus Macaques

BACKGROUND

This study evaluated dissolvable microneedle patch (dMNP) delivery of hepatitis B vaccine in rhesus macaques and provides evidence that dMNP delivery elicits seroprotective anti-HBs levels comparable with human seroprotection, potentially useful for hepatitis B birth dose vaccination in resource-constrained regions.

METHODS

Sixteen macaques were each vaccinated twice; they were treated in 4 groups, with dMNP delivery of AFV at 24 ± 8 µg (n = 4) or 48 ± 14 µg (n = 4), intramuscular injection of AFV (10 µg; n = 4), or intramuscular injection of AAV (10 µg; n = 4). Levels of antibody to hepatitis B surface antigen (HBsAg) (anti-HBs) and HBsAg-specific T-cell responses were analyzed.

RESULTS

Six of 8 animals with dMNP delivery of AFV had anti-HBs levels ≥10 mIU/mL after the first vaccine dose. After dMNP delivery of AFV, interferon γ, interleukin 2, and interleukin 4 production by HBsAg-specific T cells was detected. A statistically significant positive correlation was detected between anti-HBs levels and cells producing HBsAg-specific interferon γ and interleukin 2 (T-helper 1-type cytokine) and interleukin 4 (T-helper 2-type cytokine) in all anti-HBs-positive animals.

CONCLUSIONS

dMNP delivery of AFV can elicit seroprotective anti-HBs levels in rhesus macaques that are correlated with human seroprotection, and it could be particularly promising for birth dose delivery of hepatitis B vaccine in resource-constrained regions.

[Development of an Immune Regulation Technology Targeting the Skin and Promotion of the Practical Applications of Transcutaneous Vaccination/Immunotherapy]

In the premise of vaccination and allergen-specific immunotherapy, transcutaneous formulations have an advantage over conventional subcutaneous injections in terms of convenience, simplicity of delivery, and painless administration into the skin. Additionally, since transcutaneous formulations can be rendered cold-chain free, they do not require expert handling during transportation, storage, and stockpiling, which enables reductions in costs and distribution to distant areas. Furthermore, transcutaneous formulations are effective for improving adherence in children with phobias toward injection needles and may help in persuading them to perform self-vaccination and home immunotherapy against allergies in the future. We have been promoting the development of innovative "patch-type formulations for vaccination and immunotherapy" which regard skin as an immune organ and utilize our original transcutaneous administration devices (hydrophilic gel patch and microneedle patch) for their delivery. We have confirmed the safety and efficacy of transcutaneous formulations not only in demonstration experiments using animals but also in physician-initiated clinical studies. Additionally, in order to elucidate the mechanism for the induction of immune responses by transcutaneous formulations, we analyzed the immunological events occurring in the skin and regional lymph nodes which accompanied the application of transcutaneous administration devices or the delivery of antigens (vaccines and allergens) to the skin surface layer. This review presents our results from basic to clinical research on the development of transcutaneous formulations for vaccines and allergen-specific immunotherapy.

A Hydrogel Microneedle Patch for Point-of-Care Testing Based on Skin Interstitial Fluid

Skin interstitial fluid (ISF) holds great potential as a highly desirable sample resource for point-of-care testing (POCT), where the key is to effectively collect target biomarkers from ISF. Hydrogel microneedle patch has great promise for ISF extraction. However, it is challenging to recover target biomarkers from the extracted skin ISF in hydrogel microneedle patches in an easy-administrated, fast, and bulky instrument-free manner. Herein, a hydrogel microneedle patch made of polyvinyl alcohol (PVA) and chitosan (CS) for POCT based on the ISF is developed. The phase transition property of PVA/CS hydrogel makes the microneedles stiff when dry, which is beneficial to easily penetrate into skin. Meanwhile, the highly porous microstructure of hydrogel offers good swelling ability for extraction of ISF and the thermal degradation property of PVA makes it convenient to quickly and efficiently recover target biomarkers from microneedle patch. The capability of this platform for POCT applications is further demonstrated by successful detections of typical biomarkers collected from the mimetic skin and monitoring the glucose level in rabbit skins during a day. The developed hydrogel microneedle patch holds the advantages of extraction of skin ISF and recovery of biomarkers, thus presenting as a powerful platform for skin ISF-based POCT applications.

Fabrication and Characterization of Thiolated Chitosan Microneedle Patch for Transdermal Delivery of Tacrolimus

Microneedle patch is a prominent strategy with minimal invasion and painless application to improve skin penetration of drug molecules. Herein, we report microneedle patch (MNP) as an alternative to the oral route for the systemic delivery of tacrolimus (TM), an immunosuppressant drug. Thiolated chitosan (TCS) based microneedle patch was fabricated and characterized in vitro and in vivo for its mechanical strength, skin penetration, drug release, and skin irritation. The MNP having 225 needles with 575 μm showed good mechanical properties in terms of tensile strength and percentage elongation. The skin penetration showed 84% penetration with no breakage. Histology of the mice skin after insertion showed the penetration of needles into the dermis. In vitro release and ex vivo permeation studies through Franz diffusion cell showed the sustained release (82.5%) of TM from the MNP with significantly higher (p < 0.05) skin permeation as compared with controls, respectively. Moreover, in vivo biocompatibility in rats showed the safety of the material and patch. Thus, the TCS microneedle patch has the potential to be developed as a transdermal delivery system for tacrolimus with improved bioavailability and sustained release over a longer period.

Novel drug delivery methods for the treatment of keratitis: moving away from surgical intervention

Introduction: Corneal ulceration is one of the leading causes of blindness especially in low- and mid-income countries (LMICs). Surgical treatment of microbial keratitis is associated with multiple challenges that include non-availability of donor corneal tissues, lack of trained corneal surgeons, and poor compliance to follow up care. As a result, the surgery fails in 70-90% cases. Therefore, improving outcome of medical treatment and thereby avoiding the need for the surgery is an unmet need in the care of corneal ulcer cases.Areas covered: In this review article, the authors have tried to compile information on the novel drug-delivery systems that have potential to enhance success of medical management. We have discussed the following systems: cyclodextrins, gel formulations, colloidal system, nanoformulations, drug-eluting contact lens, microneedle patch, and ocular inserts.Expert opinion: The goals of corneal ulcer treatment are as follows: rapid eradication of causative microorganisms, control of damage from induced inflammation and microbial toxins, and facilitation of repair. The ocular surface anatomy poses several challenges for drug delivery using standard topical therapy. The novel drug-delivery systems mentioned above aim to enhanced tear solubility; superior stability; improved bio-availability; reduced toxicity; besides facilitating targeted drug delivery and convenience of administration.

Ovalbumin-Loaded Gelation Microneedles Made of Predictive Formulation by Molecular Dynamics Simulation for Enhancement of Skin Immunization

Gelation microneedle (GMNs) based vaccinations with tumor antigens have been considered to be an attractive method for transcutaneous immunization because of their superior ability to deliver vaccines through the stratum corneum (SC) in a minimally invasive manner, which subsequently induces adaptive antitumor immunity. In this study, molecular dynamics (MD) uniaxial tension simulations were conducted to predict the formulation of poly(vinyl alcohol) (PVA; possesses high water solubility) and poly(methyl vinyl ether-altmaleic anhydride) (PMVEMA; possesses high mechanical strength) blend that has the strongest mechanical properties. To validate the accuracy of the Dreiding potential for these two polymers, their densities and Hildebrand solubility parameters were first predicted using MD simulations. These values exhibited good agreement with the corresponding experimental results, indicating the accuracy of the Dreiding potential for the polymers. Regarding the simulation results, the number density of H-bonds between PVA and PMVEMA was the highest at 50% PMVEMA, which can significantly enhance the mechanical strength of pristine PVA for enhanced skin immunization. In terms of further experimental validation, evidence from mechanical strength, solubility, in vitro porcine skin penetration tests, and in vivo immunization were consistent with our simulation predictions. In addition, our results indicated that delivery of ovalbumin (OVA) using GMN patches fabricated using PVA/PMVEMA (50%/50%) provided even stronger immune responses. Using this molecular simulation procedure, the optimal fraction of PVA/PMVEMA composite for the strongest mechanical properties can be rapidly predicted to reduce research time and costs in related experiments.

In Situ Sampling and Monitoring Cell-Free DNA of the Epstein-Barr Virus from Dermal Interstitial Fluid Using Wearable Microneedle Patches

Using polymerase chain reaction and genotyping, Epstein-Barr virus cell-free DNA (EBV Cf DNA) was detectable in interstitial fluid (ISF). Microneedles offer a minimally invasive approach to capture such Cf DNA. However, a key challenge of microneedles lies in the ability to specifically isolate biomarkers within a short time. We introduced a hydrogel microneedle patch for rapid and easy capture of EBV Cf DNA from ISF in situ around 15 min, with a maximum capture efficiency of 93.6%. Then, quantification of EBV Cf DNA was achieved by electrochemical recombinase polymerase amplification wearable flexible microfluidics, with a detection limit of 3.7 × 10² copies/μL. Animal tests supported the performance of microneedles for EBV Cf DNA capture. Collectively, these data showed that the microneedle patch may have broad implications for patients with Cf DNA-related disease and cancer metastasis in minimally invasive manners.

Plasmonic Paper Microneedle Patch for On-Patch Detection of Molecules in Dermal Interstitial Fluid

Minimally invasive devices to detect molecules in dermal interstitial fluid (ISF) are desirable for point-of-care diagnostic and monitoring applications. In this study, we developed a microneedle (MN) patch that collects ISF for on-patch biomarker analysis by surface-enhanced Raman scattering (SERS). The micrometer-scale MNs create micropores in the skin surface, through which microliter quantities of ISF are collected onto plasmonic paper on the patch backing. The plasmonic paper was prepared by immobilizing poly(styrenesulfonate) (PSS) coated gold nanorods (AuNRs) on a thin strip of filter paper using plasmonic calligraphy. Negatively charged PSS was used to bind positively charged rhodamine 6G (R6G), which served as a model compound, and thereby localize R6G on AuNR surface. R6G bound on the AuNR surface was detected and quantified by acquiring SERS spectra from the plasmonic paper MN patch. This approach was used to measure pharmacokinetic profiles of R6G in ISF and serum from rats in vivo. This proof-of-concept study indicates that a plasmonic paper MN patch has the potential to enable on-patch measurement of molecules in ISF for research and future medical applications.

Extraction of Plant DNA by Microneedle Patch for Rapid Detection of Plant Diseases

In-field molecular diagnosis of plant diseases via nucleic acid amplification is currently limited by cumbersome protocols for extracting and isolating pathogenic DNA from plant tissues. To address this challenge, a rapid plant DNA extraction method was developed using a disposable polymeric microneedle (MN) patch. By applying MN patches on plant leaves, amplification-assay-ready DNA can be extracted within a minute from different plant species. MN-extracted DNA was used for direct polymerase chain reaction amplification of plant plastid DNA without purification. Furthermore, using this patch device, extraction of plant pathogen DNA ( Phytophthora infestans) from both laboratory-inoculated and field-infected leaf samples was performed for detection of late blight disease in tomato. MN extraction achieved 100% detection rate of late blight infections for samples after 3 days of inoculation when compared to the conventional gold standard cetyltrimethylammonium bromide (CTAB)-based DNA extraction method and 100% detection rate for all blind field samples tested. This simple, cell-lysis-free, and purification-free DNA extraction method could be a transformative approach to facilitate rapid sample preparation for molecular diagnosis of various plant diseases directly in the field.

Microneedle Patch-Mediated Treatment of Bacterial Biofilms

Current treatments of bacterial biofilms are limited by the poor penetration of antibiotics through their physical barrier as well as significant off-target toxicity of antibiotics and the induction of antibiotic resistance. Here we report a microneedle patch-mediated treatment for the effective elimination of biofilms by penetrating the biofilm and specifically delivering antibiotics to regions of active growth. We fabricated patches with self-dissolvable microneedles and needle tips loaded with chloramphenicol (CAM)-bearing and gelatinase-sensitive gelatin nanoparticles (CAM@GNPs). During the microneedle patch-mediated treatment, arrays of 225 microneedles simultaneously penetrate the biofilm matrix. Once inside, the microneedles dissolve and uniformly release CAM@GNPs into the surrounding area. In response to the gelatinase produced by the active bacterial community, the CAM@GNPs disassemble and release CAM into these active regions of the biofilm. Moreover, CAM@GNPs exhibited minimal off-target toxicity compared to direct CAM administration, which in turn favors wound healing. Importantly, we found that our microneedle-mediated treatment is more effective in treating Vibrio vulnificus biofilms than drug in free solution. We believe this new treatment strategy can be used to improve the delivery of a wide range of antimicrobial agents to biofilm-contaminated sites.

Glucose-Responsive Microneedle Patches for Diabetes Treatment

Antidiabetic therapeutics, including insulin as well as glucagon-like peptide 1 (GLP-1) and its analogs, are essential for people with diabetes to regulate their blood glucose levels. Nevertheless, conventional treatments based on hypodermic administration is commonly associated with poor blood glucose control, a lack of patient compliance, and a high risk of hypoglycemia. Closed-loop drug delivery strategies, also known as self-regulated administration, which can intelligently govern the drug release kinetics in response to the fluctuation in blood glucose levels, show tremendous promise in diabetes therapy. In the meantime, the advances in the development and use of microneedle (MN)-array patches for transdermal drug delivery offer an alternative method to conventional hypodermic administration. Hence, glucose-responsive MN-array patches for the treatment of diabetes have attracted increasing attentions in recent years. This review summarizes recent advances in glucose-responsive MN-array patch systems. Their opportunities and challenges for clinical translation are also discussed.

Hepatitis B vaccination using a dissolvable microneedle patch is immunogenic in mice and rhesus macaques

Chronic Hepatitis B virus infection remains a major global public health problem, accounting for about 887,000 deaths in 2015. Perinatal and early childhood infections are strongly associated with developing chronic hepatitis B. Adding a birth dose of the hepatitis B vaccine (HepB BD) to routine childhood vaccination can prevent over 85% of these infections. However, HepB BD coverage remains low in many global regions, with shortages of birth attendants trained to vaccinate and limited HepB BD supply at birth. To address the challenges, we developed coated metal microneedle patches (cMNPs) and dissolvable microneedle patches (dMNPs) that deliver adjuvant‐free hepatitis B vaccine to the skin in a simple‐to‐administer manner. The dMNP contains micron‐scale, solid needles encapsulating vaccine antigen and dissolve in the skin, generating no sharps waste. We delivered HepB BD via cMNP to BALB/c mice and via dMNP to both mice and rhesus macaques. Both cMNP and dMNP were immunogenic, generating hepatitis B surface antibody levels similar to human seroprotection. Biomechanical analysis showed that at high forces the microneedles failed mechanically by yielding but microneedles partially blunted by axial compression were still able to penetrate skin. Overall, this study indicates that with further development, dMNPs could offer a method of vaccination to increase HepB BD access and reduce needle waste in developing countries.

Enhanced Immune Responses Conferring Cross-Protection by Skin Vaccination With a Tri-Component Influenza Vaccine Using a Microneedle Patch

Skin vaccination using biodegradable microneedle patch (MNP) technology in vaccine delivery is a promising strategy showing significant advantages over conventional flu shots. In this study, we developed an MNP encapsulating a 4M2e-tFliC fusion protein and two types of whole inactivated influenza virus vaccines (H1N1 and H3N2) as a universal vaccine candidate. We demonstrated that mice receiving this tri-component influenza vaccine via MNP acquired improved IgG1 antibody responses with more balanced IgG1/IgG2a antibody responses and enhanced cellular immune responses, including increased populations of IL-4 and IFN-γ producing cells and higher frequencies of antigen-specific plasma cells compared with intramuscular injection. In addition, stronger germinal center reactions, increased numbers of Langerin-positive migratory dendritic cells, and increased cytokine secretion were observed in the skin-draining lymph nodes after immunization with the tri-component influenza MNP vaccine. The MNP-immunized group also possessed enhanced protection against a heterologous reassortant A/Shanghai/2013 H7N9 (rSH) influenza virus infection. Furthermore, the sera collected from 4M2e-tFliC MNP-immunized mice were demonstrated to have antiviral efficacy against reassortant A/Vietnam/1203/2004 H5N1 (rVet) and A/Shanghai/2013 H7N9 (rSH) virus challenges. The immunological advantages of skin vaccination with this tri-component MNP vaccine could offer a promising approach to develop an easily applicable and broadly protective universal influenza vaccine.

Mechanisms of sampling interstitial fluid from skin using a microneedle patch

Although interstitial fluid (ISF) contains biomarkers of physiological significance and medical interest, sampling of ISF for clinical applications has made limited impact due to a lack of simple, clinically useful techniques that collect more than nanoliter volumes of ISF. This study describes experimental and theoretical analysis of ISF transport from skin using microneedle (MN) patches and demonstrates collection of >1 µL of ISF within 20 min in pig cadaver skin and living human subjects using an optimized system. MN patches containing arrays of submillimeter solid, porous, or hollow needles were used to penetrate superficial skin layers and access ISF through micropores (µpores) formed upon insertion. Experimental studies in pig skin found that ISF collection depended on transport mechanism according to the rank order diffusion < capillary action < osmosis < pressure-driven convection, under the conditions studied. These findings were in agreement with independent theoretical modeling that considered transport within skin, across the interface between skin and µpores, and within µpores to the skin surface. This analysis indicated that the rate-limiting step for ISF sampling is transport through the dermis. Based on these studies and other considerations like safety and convenience for future clinical use, we designed an MN patch prototype to sample ISF using suction as the driving force. Using this approach, we collected ISF from human volunteers and identified the presence of biomarkers in the collected ISF. In this way, sampling ISF from skin using an MN patch could enable collection of ISF for use in research and medicine.

Immunotherapeutic effect of BCG-polysaccharide nucleic acid powder on Mycobacterium tuberculosis-infected mice using microneedle patches

Polysaccharide nucleic acid fractions of bacillus Calmette–Guérin, termed BCG-PSN, have traditionally been used as immunomodulators in the treatment of dermatitis and allergic diseases. While the sales of injectable BCG-PSN have shown steady growth in recent years, no reports of using BCG-PSN powder or its immunotherapeutic effects exist. Here, BCG-PSN powder was applied directly to the skin to evaluate the immunotherapeutic effects on mice infected with Mycobacterium tuberculosis (MTB). In total, 34 μg of BCG-PSN powder could be loaded into a microneedle patch (MNP). Mice receiving BCG-PSN powder delivered via MNP exhibited significantly increased IFN-γ and TNF-α production in peripheral blood CD4 + T cells and improved pathological changes in their lungs and spleens compared to control group mice. The immunotherapeutic effect of BCG-PSN powder delivered via MNP was better than that delivered via intramuscular injection to some extent. Furthermore, MNPs eliminate the side effects of syringes, and this study demonstrated that BCG-PSN can be clinically administrated in powder form.

Locally Induced Adipose Tissue Browning by Microneedle Patch for Obesity Treatment

Obesity is one of the most serious public health problems in the 21st century that may lead to many comorbidities such as type-2 diabetes, cardiovascular diseases, and cancer. Current treatments toward obesity including diet, physical exercise, pharmacological therapy, as well as surgeries are always associated with low effectiveness or undesired systematical side effects. In order to enhance treatment efficiency with minimized side effects, we developed a transcutaneous browning agent patch to locally induce adipose tissue transformation. This microneedle-based patch can effectively deliver browning agents to the subcutaneous adipocytes in a sustained manner and switch on the "browning" at the targeted region. It is demonstrated that this patch reduces treated fat pad size, increases whole body energy expenditure, and improves type-2 diabetes in vivo in a diet-induced obesity mouse model.