Dissolving Microneedle Arrays Research Articles

A Stereolithography-Based Modified Spin-Casting Method for Faster Laboratory-Scale Production of Dexamethasone-Containing Dissolving Microneedle Arrays

Microneedle arrays (MNAs) consist of a few dozens of submillimeter needles, which tend to penetrate through the stratum corneum layer of the skin and deliver hardly penetrating drugs to the systemic circulation. The application of this smart dosage form shows several advantages, such as simple use and negligible pain caused by needle punctures compared to conventional subcutaneous injections. Dissolving MNAs (DMNAs) represent a promising form of cutaneous drug delivery due to their high drug content, biocompatibility, and ease of use. Although different technologies are suitable to produce microneedle arrays (e.g., micromilling, chemical etching, laser ablation etc.), many of these are expensive or hardly accessible. Following the exponential growth of the 3D-printing industry in the last decade, high-resolution desktop printers became accessible for researchers to easily and cost-effectively design and produce microstructures, including MNAs. In this work, a low force stereolithography (LFS) 3D-printer was used to develop the dimensionally correct MNA masters for the spin-casting method. The present study aimed to develop and characterize drug-loaded DMNAs using a two-level, full factorial design for three factors focusing on the optimization of DMNA production and adequate drug content. For the preparation of DMNAs, carboxymethylcellulose and trehalose were used in certain amounts as matrices for dexamethasone sodium phosphate (DEX). Investigation of the produced DexDMNAs included mechanical analysis via texture analyzer and optical microscopy, determination of drug content and distribution with HPLC and Raman microscopy, dissolution studies via HPLC, and ex vivo qualitative permeation studies by Raman mapping. It can be concluded that a DEX-containing, mechanically stable, biodegradable DexDMNA system was successfully developed in two dosage strengths, of which both efficiently delivered the drug to the lower layers (dermis) of human skin. Moreover, the ex vivo skin penetration results support that the application of DMNAs for cutaneous drug delivery can be more effective than that of a conventional dermal gel.

Stress factors affecting protein stability during the fabrication and storage of dissolvable microneedles

Abstract Objectives The current review summarizes product and process attributes that were reported to influence protein integrity during manufacturing and storage of dissolvable microneedle arrays. It also discusses challenges in employing established protein characterization methods in dissolvable microneedle formulations. Methods Studies on dissolvable microneedles loaded with protein therapeutics that assess protein stability during or after fabrication and storage were collected. Publications addressing other types of microneedles, such as coated and vaccine-loaded microneedles, are also discussed as they face similar stability challenges. Key findings To date, various researchers have successfully incorporated proteins in dissolvable microneedles, but few publications explicitly investigated the impact of formulation and process parameters on protein stability. However, protein therapeutics are exposed to multiple thermal, physical, and chemical stressors during the fabrication and storage of microneedles. These stressors include increased temperature, shear and interfacial stress, transition to the solid state during drying, interaction with excipients, and suboptimal pH environments. While analytical methods are essential for monitoring protein integrity during manufacturing and storage, the performance of some well-established protein characterization techniques can be undermined by polymer excipients commonly employed in dissolvable microneedle formulations. Conclusions It is essential to understand the impact of key process and formulation parameters on the stability of protein therapeutics to facilitate their safe and effective administration by dissolvable microneedles.

Abstract 6754: A microneedle array patch chemo-immunotherapy for cutaneous squamous cell carcinoma

Abstract Cutaneous squamous cell carcinoma (cSCC) is the second most common human malignancy worldwide. Current therapies, including surgical excision, are associated with significant morbidities and considerable expense. Multiple efforts are now underway to develop novel therapies that are effective, durable, safe, cost-effective, and patient-friendly. Here, we report ongoing efforts to develop a localized dissolvable microneedle array patch (MAP) based therapy for cSCC. Our approach is based on the hypothesis that the delivery of an immunogenic cell death (ICD) inducing chemotherapeutic agent to the tumor microenvironment (TME) of accessible cSCCs could kill tumor cells as a source of antigen and induce a proinflammatory TME to generate a potent patient-specific anti-tumor immune response. Specifically, we evaluated MAP therapy using a UV-induced preclinical cSCC mouse model. We applied MAPs delivering the potent ICD-inducing chemotherapeutic agent, doxorubicin (DOX) to UV-induced tumors. MAPs efficiently delivered DOX to the tumor microenvironment. Compared to traditional needle injection, MAP delivery resulted in sustained high levels of DOX in the TME with minimally systemic exposure. Cell death was evident in MAP-DOX-treated tumors, and treatment resulted in tumor regression, increased survival, and long-term immune protection. Further, we found that tumor regression was associated with an early proinflammatory neutrophilic infiltrate. Taken together, our results suggest that MAP delivery of doxorubicin may be a promising approach to cSCC treatment. and that proinflammatory neutrophils are likely an important component of the early infiltrate that leads to tumor regression. Citation Format: Yufan Yang, Haotong Zhang, Cara D. Carey, Jiying Zhang, Stephen C. Balmert, Emrullah Korkmaz, Louis D. Falo. A microneedle array patch chemo-immunotherapy for cutaneous squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6754.

Dissolvable Immunomodulatory Microneedles for Treatment of Skin Wounds.

Sustained inflammation can halt or delay wound healing, and macrophages play a central role in wound healing. Inflammatory macrophages are responsible for the removal of pathogens, debris, and neutrophils, while anti-inflammatory macrophages stimulate various regenerative processes. Recombinant human Proteoglycan 4 (rhPRG4) is shown to modulate macrophage polarization and to prevent fibrosis and scarring in ear wound healing. Here, dissolvable microneedle arrays (MNAs) carrying rhPRG4 are engineered for the treatment of skin wounds. The in vitro experiments suggest that rhPRG4 modulates the inflammatory function of bone marrow-derived macrophages. Degradable and detachable microneedles are developed from gelatin methacryloyl (GelMA) attach to a dissolvable gelatin backing. The developed MNAs are able to deliver a high dose of rhPRG4 through the dissolution of the gelatin backing post-injury, while the GelMA microneedles sustain rhPRG4 bioavailability over the course of treatment. In vivo results in a murine model of full-thickness wounds with impaired healing confirm a decrease in inflammatory biomarkers such as TNF-α and IL-6, and an increase in angiogenesis and collagen deposition. Collectively, these results demonstrate rhPRG4-incorporating MNA is a promising platform in skin wound healing applications.

Transdermal delivery of IBU-PLGA nanoparticles with dissolving microneedle array patch

There are few systematic studies using microneedles to deliver ibuprofen through the skin. In this study, Ibuprofen was encapsulated in poly (lactide-co-Glycolide) (PLGA) network to form nanoparticles(IBU-NPs), then the IBU-NPs were mixed with Sodium Hyaluronate to fabricate dissolving microneedles array patch (MNP) and applied in mice model to observe its effect. In mouse model, IBU-NPs microneedles could effectively deliver ibuprofen to mice and significantly reduced the number of writhe, significantly reduced the mRNA of CGRP, COX-2, TNF–α, IL-1β, IL-6 and increased the mRNA of opioid receptor. This study introduces a rapid microneedle transdermal delivery technique for ibuprofen nanoparticles and confirms its effectiveness in terms of the mechanism of action.

MiR‐141‐3p‐Functionalized Exosomes Loaded in Dissolvable Microneedle Arrays for Hypertrophic Scar Treatment (Small 8/2024)

MiR‐141‐3p‐Functionalized Exosomes Loaded in Dissolvable Microneedle Arrays for Hypertrophic Scar Treatment (Small 8/2024)

Intradermal Vaccination with PLGA Nanoparticles via Dissolving Microneedles and Classical Injection Needles

PurposeA dissolving microneedle array (dMNA) is a vaccine delivery device with several advantages over conventional needles. By incorporating particulate adjuvants in the form of poly(D,L-lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) into the dMNA, the immune response against the antigen might be enhanced. This study aimed to prepare PLGA-NP-loaded dMNA and to compare T-cell responses induced by either intradermally injected aqueous-PLGA-NP formulation or PLGA-NP-loaded dMNA in mice.MethodsPLGA NPs were prepared with microfluidics, and their physicochemical characteristics with regard to encapsulation efficiencies of ovalbumin (OVA) and CpG oligonucleotide (CpG), zeta potentials, polydispersity indexes, and sizes were analysed. PLGA NPs incorporated dMNA was produced with three different dMNA formulations by using the centrifugation method, and the integrity of PLGA NPs in dMNAs was evaluated. The immunogenicity was evaluated in mice by comparing the T-cell responses induced by dMNA and aqueous formulations containing ovalbumin and CpG (OVA/CpG) with and without PLGA NP.ResultsPrepared PLGA NPs had a size of around 100 nm. The dMNA formulations affected the particle integrity, and the dMNA with poly(vinyl alcohol) (PVA) showed almost no aggregation of PLGA NPs. The PLGA:PVA weight ratio of 1:9 resulted in 100% of penetration efficiency and the fastest dissolution in ex-vivo human skin (< 30 min). The aqueous formulation with soluble OVA/CpG and the aqueous-PLGA-NP formulation with OVA/CpG induced the highest CD4 + T-cell responses in blood and spleen cells.ConclusionsPLGA NPs incorporated dMNA was successfully fabricated and the aqueous formulation containing PLGA NPs induce superior CD4+ and CD8+ T-cell responses.

On‐Patient Temporary Medical Record for Accurate, Time‐Sensitive Information at the Point of Care

AbstractAccurate medical recordkeeping is important for personal and public health. Conventional forms of on‐patient medical information, such as medical alert bracelets or finger‐markings, may compromise patient privacy because they are readily visible to other people. Here, the development of an invisible, temporary, and easily deployable on‐patient medical recordkeeping system is reported. Information is stored in unique patterns of spatially distributed near‐infrared (NIR) fluorescent quantum dots (QDs), which are delivered to the skin using dissolvable microneedle arrays. The patterns are invisible to the naked eye but detectable with an infrared camera, which can extract information with &gt;98% accuracy using automated pattern recognition software. By encapsulating NIR QDs in an FDA‐approved biodegradable polymer, biodegradation rates can be tuned so that the encoded medical information can be conveyed in both a spatial and temporal manner, with some components fading within 100 days and others persisting for 6 months. This may be particularly useful for administering a series of vaccinations or treatments by indicating if enough time has passed for the patient to receive the next dose. Importantly, this system contains no personal information, does not require connection to a centralized database, and is not visible to the naked eye, ensuring patient privacy.

Biotagging method for animal identification using dissolvable microneedle arrays prepared by customisable moulds

Properly handling animals and understanding their habits are crucial to establish a society where humans and animals coexist. Thus, identifying individual animals, including their possessions, and adequately managing each animal is necessary. Although several conventional identification methods exist, such as the use of ear punch, tattoos, and radio frequency (RF) chips, they require several processes and external apparatus. In this study, we proposed a new biotagging method using a microneedle array for animal identification. Our approach uses dissolvable microneedle arrays as a single patch to deliver dyes directly into the skin layer. Additionally, we developed a new fabrication method for customised female moulds to realise microneedle array patches (MAPs) with patterns of different characters and number. The characteristics and feasibility of the patterned MAPs were confirmed through basic evaluations and animal experiments. Moreover, we confirmed that patterns formed from biotagging using the developed patterned MAPs lasted over one month with clear readability. Finally, we confirmed that our patterned MAPs successfully realised biotagging on rat skin with the designated patterns including characters and number patterns. The proposed method is expected to enable minimally invasive tagging without external equipment or complex processes. In addition, the developed method could be used to embed various tags into the skin of animals and humans in the future.

Alternative approach for delivery of a depigmenting agent via dissolving microneedle arrays: Formulations and in vivo efficacy

Dissolving microneedle (DMN) arrays have gained attention as a carrier for cosmetic or pharmaceutical active compounds since they can bypass the stratum corneum to ensure delivery beyond the epidermis. In this study, we were curious whether using sodium hyaluronate (HYA) alone would be enough to fabricate DMN arrays that could yield the effective intradermal delivery and we aimed to fabricate a new concept to deliver a depigmenting agent for anti-hyperpigmentation. Thus, DMN arrays were cast by HYA with different molecular weights (MWs) and loaded with ethyl ascorbic acid (EAA). Mechanical and biological performances of DMN arrays were investigated both in vitro, ex vivo, and in vivo. The results showed that combinations of two types of HYA provided adjustable mechanical characteristics. The DMN arrays contained low MW HYA, medium MW HYA, and EAA at 70:30:20 gave the optimal in vitro properties and were selected to examine further in UVB-induced hyperpigmentation guinea pigs. The delivery of EAA, whether through the EAA-loaded DMN or the EAA solution on the pretreated skin with blank DMN, resulted in an increase in the whitening index. Hence, these two intradermal approaches demonstrated great promise and effectiveness in combating hyperpigmentation.

Analytical Study of Interstitial Fluid Extractive Microneedle Arrays Using Differential Transform Method

The computational studies of a predictive mathematical model for the extraction of interstitial (ISF) for transdermal and non-invasive diagnosis using biodegradable and hollow microneedle patch is presented in this paper. Rapid Diagnostic Tests diagnosis, which is non-invasive, affordable, straightforward, and provides results promptly and reliably, has increased access to parasite-based analysis on a global scale. Microneedle arrays are a rapidly evolving and promising technology for transdermal interstitial fluid extraction, which is used for many clinical diagnostic procedures. Hence, a developed mathematical predictive model used to optimize the design of microneedle patch for transdermal ISF extraction and subsequent diagnosis using dissolvable microneedle arrays was applied in this study. The model's solutions were obtained using the Differential Transform Method. The numerical Runge-Kutta method of fourth order was used to validate it. An experimental test result was also used to further validate the analytical results in the absence of the extracted velocity parameter. And there was a good agreement among them. Influence of dissolution rate constant, microneedle height, diffusion coefficient, velocity of ISF, microneedle ISF drug load, and density of the microneedle; were investigated. Increase in diffusion coefficient and density led to an increase in concentration of ISF extracted over time, an increase in dissolution rate led to a decrease in concentration extracted, while decrease in drug load and height, led to increase in ISF concentration extracted. A negligible effect was observed by varying the velocity of ISF extracted. The approximate analytical approach utilized in the current work has given us a more precise strategy for creating a mathematical model that predicts how ISF will be extracted from skin for use in transdermal and non-invasive rapid diagnostic tests.

A novel approach to the manufacture of dissolving microneedles arrays using aerosol jet printing

Despite much research over the last few decades, microneedle arrays for the transdermal delivery of drugs have failed to live up to their initial promise. This may be changing however as companies close in on the commercial delivery of vaccines via this technology. These breakthroughs will undoubtably increase the interest in the use of microneedles arrays for the delivery of biopharmaceuticals but will also drive research into the development of scalable manufacturing processes for their fabrication. While 3D printing is an exciting development in this field, conventional Additive Manufacturing (AM) techniques are unsuitable for biopharmaceuticals due to the harsh processing conditions which can cause degradation of the active ingredient.In this paper we report the first use of Aerosol Jet Printing (AJP) as an AM technique for the fabrication of dissolving microneedle arrays. A formulation of poly(vinyl pyrrolidone), trehalose and glycerol dissolved in water was prepared and characterised. The formulation was aerosolised using ultrasonication and deposited onto a silicon substrate. Critical process parameters such as Computer Aided Design (CAD) design, flow rate, temperature, print speed and focussing ratio were studied to determine their impact on the microneedle quality attributes. 4 × 4 microneedle arrays were printed, with needle heights > 500 µm achieved with print times of 30 mins or less. The resulting needles had sufficient strength and sharpness to penetrate porcine skin samples. Importantly, the microneedles can be fabricated under benign conditions which should be suitable for the processing and subsequent delivery of biopharmaceuticals across the skin.

MiR-141-3p-Functionalized Exosomes Loaded in Dissolvable Microneedle Arrays for Hypertrophic Scar Treatment.

Hypertrophic scar (HS) is a common fibroproliferative disease caused by abnormal wound healing after deep skin injury. However, the existing approaches have unsatisfactory therapeutic effects, which promote the exploration of newer and more effective strategies. MiRNA-modified functional exosomes delivered by dissolvable microneedle arrays (DMNAs) are expected to provide new hope for HS treatment. In this study, a miRNA, miR-141-3p, which is downregulated in skin scar tissues and in hypertrophic scar fibroblasts (HSFs), is identified. MiR-141-3p mimics inhibit the proliferation, migration, and myofibroblast transdifferentiation of HSFs in vitro by targeting TGF-β2 to suppress the TGF-β2/Smad pathway. Subsequently, the engineered exosomes encapsulating miR-141-3p (miR-141-3pOE -Exos) are isolated from adipose-derived mesenchymal stem cells transfected with Lv-miR-141-3p. MiR-141-3pOE -Exos show the same inhibitive effects as miR-141-3p mimics on the pathological behaviors of HSFs in vitro. The DMNAs for sustained release of miR-141-3pOE -Exos are further fabricated in vivo. MiR-141OE -Exos@DMNAs effectively decrease the thickness of HS and improve fibroblast distribution and collagen fiber arrangement, and downregulate the expression of α-SMA, COL-1, FN, TGF-β2, and p-Smad2/3 in the HS tissue. Overall, a promising, effective, and convenient exosome@DMNA-based miRNA delivery strategy for HS treatment is provided.

Nanosuspension-Based Dissolvable Microneedle Arrays to Enhance Diclofenac Skin Delivery.

Applying a formulation on the skin represents a patient-acceptable and therapeutically effective way to administer drugs locally and systemically. However, the stratum corneum stands as an impermeable barrier that only allows a very limited number of drugs to be distributed in the underlying tissues, limiting the feasibility of this administration route. Microneedle arrays are minimally invasive platforms that allow the delivery of drugs within/across the skin through the temporary mechanical disruption of the stratum corneum. In this work, microneedle arrays were combined with nanosuspensions, a technology for solubility enhancement of water insoluble molecules, for the skin delivery of diclofenac. Nanosuspensions were prepared using a top-down method and loaded in the tips of 500 µm or 800 µm high microneedles. The quality of the combined platform was assessed using electron microscopy and spectroscopic and calorimetry techniques, demonstrating the ability to load high amounts of the hydrophobic drug and the compatibility between excipients. Lastly, the application of nanosuspension-loaded microneedles on the skin in vitro allowed the delivery of diclofenac within and across the stratum corneum, proving the potential of this combination to enhance skin delivery of scarcely soluble drugs.

Technical evaluation of precisely manufacturing customized microneedle array patches via inkjet drug printing

Dissolvable microneedle array patches offer the possibility to deliver active pharmaceutical ingredients bypassing the gastrointestinal tract by piercing the stratum corneum. Usually, microneedles are produced by micromolding but this often results in a waste of active pharmaceutical ingredient. In this study, inkjet printing was investigated as a manufacturing technology for dissolvable microneedle array patches. A suitable ink for the printing process was developed for lisinopril as a peptidomimetic model drug. The printing process was optimized. Povidone was found to be a promising polymer for the precise and smooth production of dissolvable microneedles. Different patterns of microneedles and blank spaces were successfully printed into one microneedle array patch. It was possible to exactly define the cavities to be filled. The amount of lisinopril was precisely adjusted between 95.14 and 99.26 % of the target dose. The applied method demonstrated the precise dosage opportunities of the inkjet printing methodology for customization and drug waste reduction. Inkjet printing could be used as a precise manufacturing method for personalized microneedle array patches as well as to combine incompatible drug substances in a single patch.

A Newly Identified Spike Protein Targeted Linear B-Cell Epitope Based Dissolvable Microneedle Array Successfully Eliciting Neutralizing Activities against SARS-CoV-2 Wild-Type Strain in Mice.

Vaccination is a cost-effective medical intervention. Inactivated whole virusor large protein fragments-based severe acute respiratory syndrome coronavirus (SARS-CoV-2) vaccines have high unnecessary antigenic load to induce allergenicity and/orreactogenicity, which can be avoided by peptide vaccines of short peptide fragments that may induce highly targeted immune response. However, epitope identification and peptide delivery remain the major obstacles in developing peptide vaccines. Here, a multi-source data integrated linear B-cell epitope screening strategy is presented and a linear B-cell epitope enriched hotspot region is identified in Spike protein, from which a monomeric peptide vaccine (Epitope25) is developed and applied to subcutaneously immunize wildtype BALB/c mice. Indirect ELISA assay reveals specific and dose-dependent binding between Epitope25 and serum IgG antibodies from immunized mice. The neutralizing activity of sera from vaccinated mice is validated by pseudo and live SARS-CoV-2 wild-type strain neutralization assays. Then a dissolvable microneedle array (DMNA) is developed to pain-freely deliver Epitope25. Compared with intramuscular injection, DMNA and subcutaneous injection elicit neutralizing activities against SARS-CoV-2 wild-type strain as demonstrated by live SARS-CoV-2 virus neutralization assay. No obvious damages are found in major organs of immunized mice. This study may lay the foundation for developing linear B-cell epitope-based vaccines against SARS-CoV-2.

Potent immunogenicity and broad-spectrum protection potential of microneedle array patch-based COVID-19 DNA vaccine candidates encoding dimeric RBD chimera of SARS-CoV and SARS-CoV-2 variants

ABSTRACT Breakthrough infections by SARS-CoV-2 variants pose a global challenge to COVID-19 pandemic control, and the development of more effective vaccines of broad-spectrum protection is needed. In this study, we constructed pVAX1-based plasmids encoding receptor-binding domain (RBD) chimera of SARS-CoV-1 and SARS-CoV-2 variants, including pAD1002 (encoding RBDSARS/BA1), pAD1003 (encoding RBDSARS/Beta) and pAD131 (encoding RBDBA1/Beta). Plasmids pAD1002 and pAD131 were far more immunogenic than pAD1003 in terms of eliciting RBD-specific IgG when intramuscularly administered without electroporation. Furthermore, dissolvable microneedle array patches (MAP) greatly enhanced the immunogenicity of these DNA constructs in mice and rabbits. MAP laden with pAD1002 (MAP-1002) significantly outperformed inactivated SARS-CoV-2 virus vaccine in inducing RBD-specific IFN-γ+ effector and memory T cells, and generated T lymphocytes of different homing patterns compared to that induced by electroporated DNA in mice. In consistence with the high titer neutralization results of MAP-1002 antisera against SARS-CoV-2 pseudoviruses, MAP-1002 protected human ACE2-transgenic mice from Omicron BA.1 challenge. Collectively, MAP-based DNA constructs encoding chimeric RBDs of SARS-CoV-1 and SARS-CoV-2 variants, as represented by MAP-1002, are potential COVID-19 vaccine candidates worthy further translational study.

Dissolving Microneedle Arrays as a Hepatitis B Vaccine Delivery System Adjuvanted by APC-Targeted Poly (Lactic-co-Glycolic Acid) (PLGA) Nanoparticles

The objective of this study is to develop a new hepatitis B surface antigen (HBsAg) delivery system by coating soluble microneedle arrays with mannose-modified PLGA nanoparticles (MNPs). MNPs of different sizes were synthesized. The effects these nanoparticles on the maturation of dendritic cells were studied by flow cytometry. HBsAg-containing MNPs (HBsAg/MNPs) of the appropriate sizes were coated into water-soluble microneedle arrays. The in vitro characteristics of microneedles arrays and the immune responses after subcutaneous administration in mice were studied. The results showed that PLGA nanoparticles with an average size of about 800nm showed the most significant effects in stimulating the maturation of dendritic cells. In the water-soluble microneedle array, the targeted PLGA nanoparticles containing HBsAg were distributed discretely with a maximum distribution height of about 280μm with a drug load of 0.98 ± 0.05μg/mg. The drug-containing microneedle arrays exhibited excellent mechanical properties and improved biosafety. The results of immune responses in vivo showed that the subcutaneous administration of the microneedle arrays induced the proliferation of splenocyte, secreted specific IL-12 and IFN-γ, and promote the production of IgG in mice. This study verifies the feasibility of soluble composited microneedles administration in hepatitis B immunization, and provides new ideas for the development and application of non-injectable vaccine delivery systems.

Efficient fabrication of thermo-stable dissolving microneedle arrays for intradermal delivery of influenza whole inactivated virus vaccine.

Dissolving microneedle arrays (dMNAs) can be used to deliver vaccines via the intradermal route. Fabrication of dMNAs using centrifugation is the most common preparation method of dMNAs, but it results in a substantial loss of antigens. In order to solve the issue of antigen waste, we engineered an automatic dispensing system for dMNA preparation. Here, we report on the fabrication of influenza whole inactivated virus (WIV) vaccine-loaded dMNAs (WIV dMNAs) by using the automatic dispensing system. Prior to the dispensing process, polydimethylsiloxane (PDMS) moulds were treated with oxygen plasma to increase surface hydrophilicity. WIV dMNAs were prepared with 1% (w/v) trehalose and pullulan (50 : 50 weight ratio). During the dispensing process, reduced pressure was applied to the PDMS mould via a vacuum chamber to make microneedle cavities airless. After producing dMNAs, WIV was quantified and 1.9 μg of WIV was loaded per dMNA, of which 1.3 μg was in the microneedle tips. Compared to the centrifugation method, this automatic dispensing system resulted in a 95% reduction of antigen waste. A hemagglutination assay confirmed that WIV dMNA maintained the stability of the antigen for at least four weeks of storage, even at room temperature or at 37 °C. The WIV dMNAs displayed 100% penetration efficiency in human skin, and 83% of the microneedle volume was dissolved in the skin within 10 minutes. In a vaccination study, mice immunised with WIV dMNAs showed similar IgG levels to those that received WIV intramuscularly. In conclusion, using the automatic dispensing system for dMNA production strongly reduced antigen waste and yielded dMNAs with excellent physical, mechanical, and immunological properties.

Trilayer dissolving polymeric microneedle array loading Rose Bengal transfersomes as a novel adjuvant in early-stage cutaneous melanoma management

Melanoma remains a global concern, but current therapies present critical limitations pointing out the urgent need for novel strategies. Among these, the cutaneous delivery of drugs selectively damaging cancer cells is highly attractive. Rose Bengal (RB) is a dye exhibiting selective cytotoxicity towards melanoma, but the high water solubility and low permeability hinder its therapeutic potential. We previously developed RB-loaded transfersomes (RBTF) to mediate the RB dermal delivery; however, a platform efficiently delivering RBTF in the deepest strata is essential for a successful therapeutic activity. In this regard, dissolving microneedles release the encapsulated cargo up to the dermis, painlessly piercing the outmost skin layers. Therefore, herein we developed and characterised a trilayer dissolving microneedle array (RBTF-TDMNs) loading RBTF to maximise RBTF intradermal delivery in melanoma management. RBTF-TDMNs were proven strong enough to pierce excised porcine skin and rapidly dissolve and deposit RBTF intradermally while maintaining their physicochemical properties. Also, 3D visualisation of the system itself and while penetrating the skin was performed by multi-photon microscopy. Finally, a dermatokinetic study showed that RBTF-TDMNs offered unique delivery efficiency advantages compared to RBTF dispersion and free drug-loaded TDMNs. The proposed RBTF-TDMNs represent a valuable potential adjuvant tool for the topical management of melanoma.