Effect of microneedle design on pain in human volunteers

Battery-free optoelectronic patch for photodynamic and light therapies in treating bacteria-infected wounds

Light therapy is an effective approach for the treatment of a variety of challenging dermatological conditions. In contrast to existing methods involving high doses and large areas of illumination, alternative strategies based on wearable designs that utilize a low light dose over an extended period provide a precise and convenient treatment. In this study, we present a battery-free, skin-integrated optoelectronic patch that incorporates a coil-powered circuit, an array of microscale violet and red light emitting diodes (LEDs), and polymer microneedles (MNs) loaded with 5-aminolevulinic acid (5-ALA). These polymer MNs, based on the biodegradable composite materials of polyvinyl alcohol (PVA) and hyaluronic acid (HA), serve as light waveguides for optical access and a medium for drug release into deeper skin layers. Unlike conventional clinical photomedical appliances with a rigid and fixed light source, this flexible design allows for a conformable light source that can be applied directly to the skin. In animal models with bacterial-infected wounds, the experimental group with the combination treatment of metronomic photodynamic and light therapies reduced 2.48 log10 CFU mL-1 in bactericidal level compared to the control group, indicating an effective anti-infective response. Furthermore, post-treatment analysis revealed the activation of proregenerative genes in monocyte and macrophage cell populations, suggesting enhanced tissue regeneration, neovascularization, and dermal recovery. Overall, this optoelectronic patch design broadens the scope for targeting deep skin lesions, and provides an alternative with the functionality of standard clinical light therapy methods.

3D Printed Microneedles for the Transdermal Delivery of NAD+ Precursor: Toward Personalization of Skin Delivery

3D printing of microneedles (μNDs) for transdermal therapy has the potential to enable patient personalization based on the target disease, site of application, and dosage requirements. To convert this concept to reality, it is necessary that the 3D printing technology can deliver high resolution, an affordable cost, and large print volumes. With the introduction of benchtop 4K and 8K 3D printers, it is now possible to manufacture medical devices like μNDs at sufficient resolution and low cost. In this research, we systematically optimized the 3D printing design parameters such as resin viscosity, print angle, layer height, and curing time to generate customizable μNDs. We have also developed an innovative 3D coating microtank device to optimize the coating method. We have applied this to the development of novel μNDs to deliver an established NAD+ precursor molecule, nicotinamide mononucleotide (NMN). A methacrylate-based polymer photoresin (eSun resin) was diluted with methanol to adjust the resin viscosity. The 3D print layer height of 25 μm yielded a smooth surface, thus reducing edge-ridge mismatches. Printing μNDs at 90° to the print platform yielded 84.28 ± 2.158% (n = 5) of the input height thus increasing the tip sharpness (48.52 ± 10.43 μm, n = 5). The formulation containing fluorescein (model molecule), sucrose (viscosity modifier), and Tween-20 (surface tension modifier) was coated on the μNDs using the custom designed microtank setup, and the amount deposited was determined fluorescently. The dye-coated μND arrays inserted into human skin (in vitro) showed a fluorescence signal at a depth of 150 μm (n = 3) into the skin. After optimization of the 3D printing parameters and coating protocol using fluorescein, NMN was coated onto the μNDs, and its diffusion was assessed in full-thickness human skin in vitro using a Franz diffusion setup. Approximately 189 ± 34.5 μg (5× dipped coated μNDs) of NMN permeated through the skin and 41.2 ± 7.53 μg was left in the skin after 24 h. Multiphoton microscopy imaging of NMN-coated μND treated mouse ear skin ex vivo demonstrated significantly (p < 0.05) increased free-unbound NADPH and reduced fluorescence lifetime of NADPH, both of which are indicative of cellular metabolic rates. Our study demonstrates that low-cost benchtop 3D printers can be used to print high-fidelity μNDs with the ability to rapidly coat and release NMN which consequently caused changes in intracellular NAD+ levels.

Microneedle System Coated with Hydrogels Containing Protoporphyrin IX for Potential Application in Pharmaceutical Technology

The article aims to outline the potential of treating malignant skin cancer with microneedles covered with polymer layers containing a photosensitizer-protoporphyrin IX disodium salt (PPIX). The usefulness of stereolithography (SLA), which is a form of 3D-printing technology, for the preparation of a microneedle system with protoporphyrin IX was demonstrated. The SLA method allowed for pyramid-shaped microneedles to be printed that were covered with three different 0.1% PPIX hydrogels based on sodium alginate, xanthan, and poloxamer. Rheological tests and microscopic analysis of the hydrogels were performed. Microneedles coated with two layers of poloxamer-based hydrogel containing 0.1% PPIX were subjected to release tests in Franz diffusion cells. The release profile of PPIX initially increased and then remained relatively constant. The amount of substance released after a four-hour test in three Franz cells was 0.2569 ± 0.0683 mg/cm2. Moreover, the acute toxicity of this type of microneedle was assessed using the Microtox system. The obtained results show the usefulness of further development studies on microneedles as carriers of photosensitizing agents.

Monoclonal Antibody Delivery Using 3D Printed Biobased Hollow μNe3dle Arrays for the Treatment of Osteoporosis

Transdermal microneedles have demonstrated promising potential as an alternative to typical drug administration routes for the treatment of various diseases. As microneedles offer lower administration burden with enhanced patient adherence and reduced ecological footprint, there is a need for further exploitation of microneedle devices. One of the main objectives of this work was to initially develop an innovative biobased photocurable resin with high biobased carbon content comprising isobornyl acrylate (IBA) and pentaerythritol tetraacrylate blends (50:50 wt/wt). The optimization of the printing and curing process resulted in μNe3dle arrays with durable mechanical properties and piercing capacity. Another objective of the work was to employ the 3D printed hollow μNe3dles for the treatment of osteoporosis in vivo. The 3D printed μNe3dle arrays were used to administer denosumab (Dmab), a monoclonal antibody, to osteoporotic mice, and the serum concentrations of critical bone minerals were monitored for six months to assess recovery. It was found that the Dmab administered by the 3D printed μNe3dles showed fast in vitro rates and induced an enhanced therapeutic effect in restoring bone-related minerals compared to subcutaneous injections. The findings of this study introduce a novel green approach with a low ecological footprint for 3D printing of biobased μNe3dles, which can be tailored to improve clinical outcomes and patient compliance for chronic diseases.

Research Progress of Hydrogel Microneedles in Wound Management

Microneedles are a novel drug delivery system that offers advantages such as safety, painlessness, minimally invasive administration, simplicity of use, and controllable drug delivery. As a type of polymer microneedle with a three-dimensional network structure, hydrogel microneedles (HMNs) possess excellent biocompatibility and biodegradability and encapsulate various therapeutic drugs while maintaining drug activity, thus attracting significant attention. Recently, they have been widely employed to promote wound healing and have demonstrated favorable therapeutic effects. Although there are reviews about HMNs, few of them focus on wound management. Herein, we present a comprehensive overview of the design and preparation methods of HMNs, with a particular emphasis on their application status in wound healing, including acute wound healing, infected wound healing, diabetic wound healing, and scarless wound healing. Finally, we examine the advantages and limitations of HMNs in wound management and provide suggestions for future research directions.

Simple, ultrasensitive detection of superoxide anion radical mutations in melanoma mice with SERS microneedles

Elevated levels of superoxide anion radicals (O2·-) have been implicated in the pathogenesis of a variety of diseases, such as cancer, inflammatory diseases and autoimmune diseases. To determine the O2·- concentration for assisting disease detection, a method based on surface-enhanced Raman scattering (SERS) combined with transparent polymer microneedles has been developed. Photocrosslinked NOA61 is used to prepare microneedles with sulfhydryl group, which can contribute to anchor gold nanoparticles (Au NPs) functionalized by p-mercaptobenzoic acid (PATP). This work successfully constructed SERS microneedles for in situ detection. A REDOX reaction occurred between PATP and O2·-, resulting in the formation of dimethylaminoborane (DMAB) and a subsequent change in Raman signal. Based on the quantitative relationship between the change of peak area ratio at 1042 cm-1 and 1077 cm-1 and the concentration change of O2·-, a standard curve with a linear range of 0-480 ng/mL was constructed. The SERS microneedles were effectively employed to track melanoma progression in mice, establishing a fundamental correlation between O2·- concentration and melanoma stage, as confirmed by ELISA. The benefits of this approach, including convenience, in situ applicability, and low cost, are anticipated to offer novel insights for non-invasive in situ detection, potentially enhancing disease monitoring and diagnosis.

Machine Learning Assists in the Design and Application of Microneedles

Microneedles (MNs), characterized by their micron-sized sharp tips, can painlessly penetrate the skin and have shown significant potential in disease treatment and biosensing. With the development of artificial intelligence (AI), the design and application of MNs have experienced substantial innovation aided by machine learning (ML). This review begins with a brief introduction to the concept of ML and its current stage of development. Subsequently, the design principles and fabrication methods of MNs are explored, demonstrating the critical role of ML in optimizing their design and preparation. Integration between ML and the applications of MNs in therapy and sensing were further discussed. Finally, we outline the challenges and prospects of machine learning-assisted MN technology, aiming to advance its practical application and development in the field of smart diagnosis and treatment.

Hydrogel forming microneedles loaded with VEGF and Ritlecitinib/polyhydroxyalkanoates nanoparticles for mini-invasive androgenetic alopecia treatment

Androgenetic alopecia (AGA), the most prevalent clinical hair loss, lacks safe and effective treatments due to downregulated angiogenic genes and insufficient vascularization in the perifollicular microenvironment of the bald scalp in AGA patients. In this study, a hyaluronic acid (HA) based hydrogel-formed microneedle (MN) was designed, referred to as V-R-MNs, which was simultaneously loaded with vascular endothelial growth factor (VEGF) and the novel hair loss drug Ritlecitinib, the latter is encapsulated in slowly biodegradable polyhydroxyalkanoates (PHAs) nanoparticles (R-PHA NPs) for minimally invasive AGA treatment. The integration of HA based hydrogel alongside PHA nanoparticles significantly bolstered the mechanical characteristics of microneedles and enhanced skin penetration efficiency. Due to the biosafety, mechanical strength, and controlled degradation properties of HA hydrogel formed microneedles, V-R-MNs can effectively penetrate the skin's stratum corneum, facilitating the direct delivery of VEGF and Ritlecitinib in a minimally invasive, painless and long-term sustained release manner. V-R-MNs not only promoted angiogenesis and improve the immune microenvironment around the hair follicle to promote the proliferation and development of hair follicle cells, but also the application of MNs to the skin to produce certain mechanical stimulation could also promote angiogenesis. In comparison to the clinical drug minoxidil for AGA treatment, the hair regeneration effect of V-R-MN in AGA model mice is characterized by a rapid onset of the anagen phase, improved hair quality, and greater coverage. This introduces a new, clinically safer, and more efficient strategy for AGA treatment, and serving as a reference for the treatment of other related diseases.

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.

Fabrication and evaluation of nanoemulsion based insulin loaded microneedles for transdermal drug delivery

Aim: Insulin therapy require self-administration of subcutaneous injection leading to painful and inconvenient drug therapy. The aim is to fabricate nanoemulsion (NE) based insulin loaded microneedles with improved bioavailability and patient compliance.Materials & methods: Different ratios of polyvinyl alcohol and polyvinylpyrrolidone as polymers were prepared through micro-molding technique for microneedles. Characterization of were performed using scanning electron microscope, differential scanning calorimetry, Fourier-transform infrared spectroscopy and circular dichroism. Mechanical strength, hygroscopicity and pain perception of these microneedles were also evaluated. In vitro release, permeation and in vivo PK/PD study of NE-based microneedles were conducted.Results: NE-based microneedles of insulin have improved bioavailability and quick response.Conclusion: Microneedles loaded with insulin can be effectively delivered insulin transdermally to treat diabetes with increased convenience and patient compliance.

Microneedle Patches-Integrated Transdermal Bioelectronics for Minimally Invasive Disease Theranostics

Wearable epidermal electronics with non- or minimally-invasive characteristics can collect, transduce, communicate, and interact with accessible physicochemical health indicators on the skin. However, due to the stratum corneum layer, rich information about body health is buried under the skin stratum corneum layer, for example, in the skin interstitial fluid. Microneedle patches are typically designed with arrays of special microsized needles of length within 1000 µm. Such characteristics potentially enable the access and sample of biomolecules under the skin or give therapeutical treatment painlessly and transdermally. Integrating microneedle patches with various electronics allows highly efficient transdermal bioelectronics, showing their great promise for biomedical and healthcare applications. This comprehensive review summarizes and highlights the recent progress on integrated transdermal bioelectronics based on microneedle patches. The design criteria and state-of-the-art fabrication techniques for such devices are initially discussed. Next, devices with different functions, including but not limited to health monitoring, drug delivery, and therapeutical treatment, are highlighted in detail. Finally, key issues associated with current technologies and future opportunities are elaborated to sort out the state of recent research, point out potential bottlenecks, and provide future research directions.

Chrono-tailored drug delivery systems: recent advances and future directions

Circadian rhythms influence a range of biological processes within the body, with the central clock or suprachiasmatic nucleus (SCN) in the brain synchronising peripheral clocks around the body. These clocks are regulated by external cues, the most influential being the light/dark cycle, in order to synchronise with the external day. Chrono-tailored or circadian drug delivery systems (DDS) aim to optimise drug delivery by releasing drugs at specific times of day to align with circadian rhythms within the body. Although this approach is still relatively new, it has the potential to enhance drug efficacy, minimise side effects, and improve patient compliance. Chrono-tailored DDS have been explored and implemented in various conditions, including asthma, hypertension, and cancer. This review aims to introduce the biology of circadian rhythms and provide an overview of the current research on chrono-tailored DDS, with a particular focus on immunological applications and vaccination. Finally, we draw on some of the key challenges which need to be overcome for chrono-tailored DDS before they can be translated to more widespread use in clinical practice.

Long-acting transdermal drug delivery formulations: Current developments and innovative pharmaceutical approaches

Transdermal administration remains an active research and development area as an alternative route for long-acting drug delivery. It avoids major drawbacks of conventional oral (gastrointestinal side effects, low drug bioavailability, and need for multiple dosing) or parenteral routes (invasiveness, pain, and psychological stress and bio-hazardous waste generated from needles), thereby increasing patient appeal and compliance. This review focuses on the current state of long-acting transdermal drug delivery, including adhesive patches, microneedles, and molecularly imprinted polymeric systems. Each subsection describes an approach including key considerations in formulation development, design, and process parameters with schematics. An overview of commercially available conventional (adhesive) patches for long-acting drug delivery (longer than 24 h), the reservoir- and matrix-type systems under preclinical evaluation, as well as the advanced transdermal formulations, such as the core-shell, nanoformulations-incorporated and stimuli-responsive microneedles, and 3D-printed and molecularly imprinted polymers that are in development, is also provided. Finally, we elaborated on translational aspects, challenges in patch formulation development, and future directions for the clinical advancement of new long-acting transdermal products.

Transdermal microneedle patches as a promising drug delivery system for anti-obesogenic molecules

Obesity, characterized by excessive storage of lipids, has become a global pandemic with high incidence levels, and its forecast is not encouraging. Currently, there are different strategies to treat obesity; however, these conventional methods have various limitations. Lifestyle changes may result in poor outcomes due to the complexity of obesity causes, pharmaceutic treatments produce severe side effects, and bariatric surgery is highly invasive. In the search for alternative treatments to fight obesity, transdermal drug delivery systems of anti-obesogenic molecules have gained particular attention. However, the diffusion of molecules through the skin is the main drawback due to the characteristics of different layers of the skin, principally the stratum corneum and its barrier-like behavior. In this sense, microneedles patches (MP) have emerged to overcome this limitation by piercing the skin and allowing drug delivery inside the body. Although MP have been studied for some years, it was not until about 2017 that their potential as anti-obesogenic treatment was reported. This article aims to summarize and analyze the strategies employed to produce MP and to embed the active molecules against obesity. Special attention is focused on the microneedle's material, geometry, array, and additional delivery strategies, like nanoencapsulation. MP are a promising tool to develop an easy-access treatment, avoiding the digestive tract and with the capacity to enhance the anti-obesogenic activity by delivering one or more active molecules.

Wearable Vertical Graphene-Based Microneedle Biosensor for Real-Time Ketogenic Diet Management

Ketogenic diets have attracted substantial interest in the treatment of chronic diseases, but there are health risks with long-term regimes. Despite the advancements in diagnostic and therapeutic methods in modern medicine, there is a huge gap in personalized health management of this dietary strategy. Hence, we present a wearable microneedle biosensor for real-time ketone and glucose monitoring. The microneedle array possesses excellent mechanical properties, allowing for consistent sampling of interstitial biomarkers while reducing the pain associated with skin puncture. Vertical graphene with outstanding electrical conductivity provides the resulting sensor with a high sensitivity of 234.18 μA mM-1 cm-2 and a low limit detection of 1.21 μM. When this fully integrated biosensor was used in human volunteers, it displayed an attractive analytical capability for tracking the dynamic metabolite levels. Moreover, the results of the on-body evaluation established a significant correlation with commercial blood measurements. Overall, this cost-effective and efficient sensing platform can accelerate the application of a ketogenic diet in personal nutrition and wellness management.

Rapid Correction of the Hypoglycemia State in Nonhuman Primates Using a Glucagon Long-Dissolving Microneedle Patch

The timely administration of glucagon is a standard clinical practice for the treatment of severe hypoglycemia. However, the process involves cumbersome steps, including the reconstitution of labile glucagon and filling of the syringe, which cause considerable delays in emergency situations. Moreover, multiple dosages are often required to prevent the recurrence of the hypoglycemic episode because of the short half-life of glucagon in plasma. Herein, we develop a glucagon-loaded long-dissolving microneedle (GLMN) patch that exhibits the properties of fast onset and sustained activity for the effective treatment of severe hypoglycemia. Three types of MN patches were fabricated with different dimensions (long, medium, and short). The longer MN patch packaged a higher dosage of glucagon and exhibited supreme mechanical strength compared to the shorter one. Additionally, the longer MN patch could insert more deeply into the skin, resulting in higher permeability of glucagon across the skin tissue and more rapid systemic absorption as compared with the shorter MN patch. The GLMN patch was observed to reverse the effects of hypoglycemia within 15 min of application in animal models (specifically, rat and rhesus monkey models) and maintained long-term glycemic control, owing to highly efficient drug permeation and the drug reservoir effect of the MN base. The current study presents a promising strategy for the rapid reversal of severe hypoglycemia that exhibits the desirable properties of easy use, high efficiency, and sustained action.

Targeting Diverse Wounds and Scars: Recent Innovative Bio-design of Microneedle Patch for Comprehensive Management

Wounds and the subsequent formation of scars constitute a unified and complex phased process. Effective treatment is crucial; however, the diverse therapeutic approaches for different wounds and scars, as well as varying treatment needs at different stages, present significant challenges in selecting appropriate interventions. Microneedle patch (MNP), as a novel minimally invasive transdermal drug delivery system, has the potential for integrated and programmed treatment of various diseases and has shown promising applications in different types of wounds and scars. In this comprehensive review, the latest applications and biotechnological innovations of MNPs in these fields are thoroughly explored, summarizing their powerful abilities to accelerate healing, inhibit scar formation, and manage related symptoms. Moreover, potential applications in various scenarios are discussed. Additionally, the side effects, manufacturing processes, and material selection to explore the clinical translational potential are investigated. This groundwork can provide a theoretical basis and serve as a catalyst for future innovations in the pursuit of favorable therapeutic options for skin tissue regeneration.

A Hollow Microneedle Equipped with a Micropillar for Improved Needle Insertion and Injection of Drug Solution

PURPOSE

Hollow-type microneedles (hMNs) are a promising device for the effective administration of drugs into intradermal sites. Complete insertion of the needle into the skin and administration of the drug solution without leakage must be achieved to obtain bioavailability or a constant effect. In the present study, several types of hMN with or without a rounded blunt tip micropillar, which suppresses skin deformation, around a hollow needle, and the effect on successful needle insertion and administration of a drug solution was investigated. Six different types of hMNs with needle lengths of 1000, 1300, and 1500 µm with or without a micropillar were used.

METHODS

Needle insertion and the disposition of a drug in rat skin were investigated. In addition, the displacement-force profile during application of hMNs was also investigated using a texture analyzer with an artificial membrane to examine needle factors affecting successful insertion and administration of a drug solution by comparing with in vivo results.

RESULTS

According to the results with the drug distribution of iodine, hMN1300 with a micropillar was able to successfully inject drug solution into an intradermal site with a high success rate. In addition, the results of displacement-force profiles with an artificial membrane showed that a micropillar can be effective for depth control of the injected solution as well as the prevention of contact between the hMN pedestal and the deformed membrane.

CONCLUSION

In the present study, hMN1300S showed effective solution delivery into an intradermal site. In particular, a micropillar can be effective for depth control of the injected solution as well as preventing contact between the hMN pedestal and the deformed membrane. The obtained results will help in the design and development of hMNs that ensure successful injection of an administered drug.

Microneedles loaded with cerium-manganese oxide nanoparticles for targeting macrophages in the treatment of rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a prevalent inflammatory autoimmune disease characterised by persistent inflammation and joint damage with elevated levels of reactive oxygen species (ROS). Current treatment modalities for RA have significant limitations, including poor bioavailability, severe side effects, and inadequate targeting of inflamed joints. Herein, we synthesised cerium/manganese oxide nanoparticles (NPs) as efficient drug carriers with antioxidant and catalytic-like functions that can eliminate ROS to facilitate the polarization of macrophages phenotype from M1 to M2 and alleviate inflammation. Methotrexate (MTX), a first-line RA medication, was loaded into the NPs, which were further modified with bovine serum albumin (BSA) and integrated into dissolving hyaluronic acid-based microneedles (MNs) for transdermal delivery.

RESULT

This innovative approach significantly enhanced drug delivery efficiency, reduced RA inflammation, and successfully modulated macrophage polarization toward an anti-inflammatory phenotype.

CONCLUSION

This research not only presents a promising drug delivery strategy for RA but also contributes broadly to the field of immune disease treatment by offering an advanced approach for macrophage phenotypic reprogramming.

Innovative freeze-drying technique in the fabrication of dissolving microneedle patch: Enhancing transdermal drug delivery efficiency

Microneedle patch (MNP) has become a hot research topic in the field of transdermal drug delivery due to its ability to overcome the stratum corneum barrier. Among the various types of microneedles, dissolving microneedles represent one of the most promising transdermal delivery methods. However, the most used method for preparing dissolving microneedles, namely microfabrication, suffers from issues such as long drying time, susceptibility to humidity, and large batch-to-batch variability, which limit the development of dissolving microneedles. In this study, we report for the first time a method for preparing dissolving microneedles using freeze-drying technology. We screened substrates suitable for freeze-dried microneedle patch (FD-MNP) and used coating technology to enhance the mechanical strength of FD-MNP, allowing them to meet the requirements for skin penetration. We successfully prepared FD-MNP using hyaluronic acid as the substrate and insulin as the model drug. Scanning electron microscopy revealed that the microneedles had a porous structure. After coating, the mechanical strength of the microneedles was 0.61 N/Needle, and skin penetration rate was 97%, with a penetration depth of 215 μm. The tips of the FD-MNP dissolved completely within approximately 60 s after skin penetration, which is much faster than conventional MNP (180 s). In vitro transdermal experiments showed that the FD-MNP shortened the lag time for transdermal delivery of rhodamine 123 and insulin compared to conventional MNP, indicating a faster transdermal delivery rate. Pharmacological experiments showed that the FD-MNP lowered mouse blood glucose levels more effectively than conventional MNP, with a relative pharmacological availability of 96.59 ± 2.84%, higher than that of conventional MNP (84.34 ± 3.87%), P = 0.0095. After storage under 40℃ for two months, the insulin content within the FD-MNP remained high at 95.27 ± 4.46%, which was much higher than that of conventional MNP (58.73 ± 3.71%), P < 0.0001. In conclusion, freeze-drying technology is a highly valuable method for preparing dissolving microneedles with potential applications in transdermal drug delivery.

A microneedle vaccine printer for thermostable COVID-19 mRNA vaccines

Decentralized manufacture of thermostable mRNA vaccines in a microneedle patch (MNP) format could enhance vaccine access in low-resource communities by eliminating the need for a cold chain and trained healthcare personnel. Here we describe an automated process for printing MNP Coronavirus Disease 2019 (COVID-19) mRNA vaccines in a standalone device. The vaccine ink is composed of lipid nanoparticles loaded with mRNA and a dissolvable polymer blend that was optimized for high bioactivity by screening formulations in vitro. We demonstrate that the resulting MNPs are shelf stable for at least 6 months at room temperature when assessed using a model mRNA construct. Vaccine loading efficiency and microneedle dissolution suggest that efficacious, microgram-scale doses of mRNA encapsulated in lipid nanoparticles could be delivered with a single patch. Immunizations in mice using manually produced MNPs with mRNA encoding severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein receptor-binding domain stimulate long-term immune responses similar to those of intramuscular administration.

Inkjet Printing of Pharmaceuticals

Inkjet printing (IJP) is an additive manufacturing process that selectively deposits ink materials, layer-by-layer, to create 3D objects or 2D patterns with precise control over their structure and composition. This technology has emerged as an attractive and versatile approach to address the ever-evolving demands of personalized medicine in the healthcare industry. Although originally developed for nonhealthcare applications, IJP harnesses the potential of pharma-inks, which are meticulously formulated inks containing drugs and pharmaceutical excipients. Delving into the formulation and components of pharma-inks, the key to precise and adaptable material deposition enabled by IJP is unraveled. The review extends its focus to substrate materials, including paper, films, foams, lenses, and 3D-printed materials, showcasing their diverse advantages, while exploring a wide spectrum of therapeutic applications. Additionally, the potential benefits of hardware and software improvements, along with artificial intelligence integration, are discussed to enhance IJP's precision and efficiency. Embracing these advancements, IJP holds immense potential to reshape traditional medicine manufacturing processes, ushering in an era of medical precision. However, further exploration and optimization are needed to fully utilize IJP's healthcare capabilities. As researchers push the boundaries of IJP, the vision of patient-specific treatment is on the horizon of becoming a tangible reality.

Egg microneedles for transdermal vaccination of inactivated influenza virus

The use of dissolving microneedles (DMNs) is a drug delivery technique in which drug dissolution occurs once it is administered into the skin. The skin is a remarkable site for vaccination due to its significant immunologic properties. Compared to the traditional hypodermic intramuscular (IM) injection, vaccination via DMN does not require cold chains and allows for minimal invasive drug delivery. On account of the significance of skin vaccination, preceding studies have been conducted to elucidate the importance of the DMN technology in vaccination. Most of these studies focused on formulations that maintain the activity of the vaccine, so formulations designed to be specific to the mechanical properties of the microneedle could not be used together independently. In this study, we have developed influenza vaccine loaded egg microneedles (EMN) and characterized the specificity of layer-specific functions of EMN by distinguishing between formulations that can maintain the activity of the vaccine and have the mechanical strength. By the use of in vitro tests such as ELISA and SRID assays, we quantitively evaluated the antigen activity of the formulation candidates to be 87% and 91%, respectively. In vivo tests were also conducted as mouse groups were inoculated with the formulation constructed into egg microneedles (FLU-EMN) to determine the protective efficacy against infection. The results demonstrated that FLU-EMN with functionalized formulations successfully enabled protective immune response even with a fractional dose compared to IM injection.

Design and fabrication of customizable microneedles enabled by 3D printing for biomedical applications

Microneedles (MNs) is an emerging technology that employs needles ranging from 10 to 1000 μm in height, as a minimally invasive technique for various procedures such as therapeutics, disease monitoring and diagnostics. The commonly used method of fabrication, micromolding, has the advantage of scalability, however, micromolding is unable to achieve rapid customizability in dimensions, geometries and architectures, which are the pivotal factors determining the functionality and efficacy of the MNs. 3D printing offers a promising alternative by enabling MN fabrication with high dimensional accuracy required for precise applications, leading to improved performance. Furthermore, enabled by its customizability and one-step process, there is propitious potential for growth for 3D-printed MNs especially in the field of personalized and on-demand medical devices. This review provides an overview of considerations for the key parameters in designing MNs, an introduction on the various 3D-printing techniques for fabricating this new generation of MNs, as well as highlighting the advancements in biomedical applications facilitated by 3D-printed MNs. Lastly, we offer some insights into the future prospects of 3D-printed MNs, specifically its progress towards translation and entry into market.

Polymer Delivery Systems for Long-Acting Antiretroviral Drugs

The success of long-acting (LA) drug delivery systems (DDSs) is linked to their biocompatible polymers. These are used for extended therapeutic release. For treatment or prevention of human immune deficiency virus type one (HIV-1) infection, LA DDSs hold promise for improved regimen adherence and reduced toxicities. Current examples include Cabenuva, Apretude, and Sunlenca. Each is safe and effective. Alternative promising DDSs include implants, prodrugs, vaginal rings, and microarray patches. Each can further meet patients' needs. We posit that the physicochemical properties of the formulation chemical design can optimize drug release profiles. We posit that the strategic design of LA DDS polymers will further improve controlled drug release to simplify dosing schedules and improve regimen adherence.

Vac-and-fill: A micromoulding technique for fabricating microneedle arrays with vacuum-activated, hands-free mould-filling

We report a simple and reproducible micromoulding technique that dynamically fills microneedle moulds with a liquid formulation, using a plastic syringe, triggered by the application of vacuum ('vac-and-fill'). As pressure around the syringe drops, air inside the syringe pushes the plunger to uncover an opening in the syringe and fill the microneedle mould without manual intervention, therefore removing inter-operator variability. The technique was validated by monitoring the plunger movement and pressure at which the mould would be filled over 10 vacuum cycles for various liquid formulation of varying viscosity (water, glycerol, 20 % polyvinylpyrrolidone (PVP) solution or 40 % PVP solution). Additionally, the impact of re-using the disposable syringes on plunger movement, and thus the fill pressure, was investigated using a 20 % PVP solution. The fill pressure was consistent at 300-450 mbar. It produced well-formed and mechanically robust PVP, poly(methylvinylether/maleic anhydride) and hydroxyethylcellulose microneedles from liquid formulations. This simple and inexpensive technique of micromoulding eliminated the air entrapment and bubble formation, which prevent reproducible microneedle formation, in the resultant microneedle arrays. It provides a cost-effective alternative to the conventional micromoulding techniques, where the application of vacuum ('fill-and-vac') or centrifugation following mould-filling may be unsuitable, ineffective or have poor reproducibility.

Microneedles: A Versatile Drug Delivery Carrier for Phytobioactive Compounds as a Therapeutic Modulator for Targeting Mitochondrial Dysfunction in the Management of Neurodegenerative Diseases

Neurodegenerative disease (ND) is the fourth leading cause of death worldwide, with limited symptomatic therapies. Mitochondrial dysfunction is a major risk factor in the progression of ND, and it-increases the generation of reactive oxygen species (ROS). Overexposure to these ROS induces apoptotic changes leading to neuronal cell death. Many studies have shown the prominent effect of phytobioactive compounds in managing mitochondrial dysfunctions associated with ND, mainly due to their antioxidant properties. The drug delivery to the brain is limited due to the presence of the blood-brain barrier (BBB), but effective drug concentration needs to reach the brain for the therapeutic action. Therefore, developing safe and effective strategies to enhance drug entry in the brain is required to establish ND's treatment. The microneedle-based drug delivery system is one of the effective non-invasive techniques for drug delivery through the transdermal route. Microneedles are micronsized drug delivery needles that are self-administrable. It can penetrate through the stratum corneum skin layer without hitting pain receptors, allowing the phytobioactive compounds to be released directly into systemic circulation in a controlled manner. With all of the principles mentioned above, this review discusses microneedles as a versatile drug delivery carrier for the phytoactive compounds as a therapeutic potentiating agent for targeting mitochondrial dysfunction for the management of ND.

Microneedle and Polymeric Films: Delivery of Proteins, Peptides and Nucleic Acids

In the last 20 years, protein, peptide and nucleic acid-based therapies have become the fastest growing sector in the pharmaceutical industry and play a vital role in disease therapy. However, the intrinsic sensitivity and large molecular sizes of biotherapeutics limit the available routes of administration. Currently, the main administration routes of biomacromolecules, such as parenteral, oral, pulmonary, nasal, rectal and buccal routes, each have their limitations. Several non-invasive strategies have been proposed to overcome these challenges. Researchers were particularly interested in microneedles (MNs) and polymeric films because of their less invasiveness, convenience and greater potential to preserve the bioactivity of biotherapeutics. By facilitating with MNs and polymeric films, biomacromolecules could provide significant benefits to patients suffering from various diseases such as cancer, diabetes, infectious and ocular diseases. However, before these devices can be used on patients, how to upscale MN manufacture in a cost-effective and timely manner, as well as the long-term safety of MN and polymeric film applications necessitates further investigation.

Microarray needles comprised of arginine-modified chitosan/PVA hydrogel for enhanced antibacterial and wound healing potential of curcumin

Wound healing is a multifaceted and complex process that includes inflammation, hemostasis, remodeling, and granulation. Failures in any link may cause the healing process to be delayed. As a result, wound healing has always been a main research focus across the entire medical field, posing significant challenges and financial burdens. Hence, the current investigation focused on the design and development of arginine-modified chitosan/PVA hydrogel-based microneedles (MNs) as a curcumin (CUR) delivery system for improved wound healing and antibacterial activity. The substrate possesses exceptional swelling capabilities that allow tissue fluid from the wound to be absorbed, speeding up wound closure. The antibacterial activity of MNs was investigated against S. aureus and E. coli. The results revealed that the developed CUR-loaded MNs had increased antioxidant activity and sustained drug release behavior. Furthermore, after being loaded in the developed MNs, it revealed improved antibacterial activity of CUR. Wound healing potential was assessed by histopathological analysis and wound closure%. The observed results suggest that the CUR-loaded MNs greatly improved wound healing potential via tissue regeneration and collagen deposition, demonstrating the potential of developed MNs patches to be used as an effective carrier for wound healing in healthcare settings.

Safety tests and clinical research on buccal and nasal microneedle swabs for genomic analysis

Conventional swabs have been used as a non-invasive method to obtain samples for DNA analysis from the buccal and the nasal mucosa. However, swabs may not always collect pure enough genetic material. In this study, buccal and nasal microneedle swab is developed to improve the accuracy and reliability of genomic analysis. A cytotoxicity test, a skin sensitivity test, and a skin irritation test are conducted with microneedle swabs. Polymer microneedle swabs meet the safety requirements for clinical research and commercial use. When buccal and nasal microneedle swabs are used, the amount of genetic material obtained is greater than that from commercially available swabs, and DNA purity is also high. The comparatively short microneedle swab (250 μm long) cause almost no pain to all 25 participants. All participants also report that the microneedle swabs are very easy to use. When genotypes are compared at five SNP loci from blood of a participant and from that person's buccal or nasal microneedle swab, the buccal and nasal microneedle swabs show 100% concordance for all five SNP genotypes. Microneedle swabs can be effectively used for genomic analysis and prevention through genomic analysis, so the utilization of microneedle swabs is expected to be high.

Opportunities and challenges in the diagnostic utility of dermal interstitial fluid

The volume of interstitial fluid (ISF) in the human body is three times that of blood. Yet, collecting diagnostically useful ISF is more challenging than collecting blood because the extraction of dermal ISF disrupts the delicate balance of pressure between ISF, blood and lymph, and because the triggered local inflammation further skews the concentrations of many analytes in the extracted fluid. In this Perspective, we overview the most meaningful differences in the make-up of ISF and blood, and discuss why ISF cannot be viewed generally as a diagnostically useful proxy for blood. We also argue that continuous sensing of small-molecule analytes in dermal ISF via rapid assays compatible with nanolitre sample volumes or via miniaturized sensors inserted into the dermis can offer clinically advantageous utility, particularly for the monitoring of therapeutic drugs and of the status of the immune system.

Current Status of Microneedle Array Technology for Therapeutic Delivery: From Bench to Clinic

In recent years, microneedle (MN) patches have emerged as an alternative technology for transdermal delivery of various drugs, therapeutics proteins, and vaccines. Therefore, there is an urgent need to understand the status of MN-based therapeutics. The article aims to illustrate the current status of microneedle array technology for therapeutic delivery through a comprehensive review. However, the PubMed search was performed to understand the MN's therapeutics delivery status. At the same time, the search shows the number no of publications on MN is increasing (63). The search was performed with the keywords "Coated microneedle," "Hollow microneedle," "Dissolvable microneedle," and "Hydrogel microneedle," which also shows increasing trend. Similarly, the article highlighted the application of different microneedle arrays for treating different diseases. The article also illustrated the current status of different phases of MN-based therapeutics clinical trials. It discusses the delivery of different therapeutic molecules, such as drug molecule delivery, using microneedle array technology. The approach mainly discusses the delivery of different therapeutic molecules. The leading pharmaceutical companies that produce the microneedle array for therapeutic purposes have also been discussed. Finally, we discussed the limitations and future prospects of this technology.

Radiofrequency Microneedling: Technology, Devices, and Indications in the Modern Plastic Surgery Practice

Background

Since the initial invention of microneedling, advancements have been made to improve the desired effects. The addition of radiofrequency to microneedling devices was developed within the past decade as a way to induce thermal injury and increase dermal heating to enhance the dermal wound healing cascade.

Objectives

With an overabundance of literature and mainstream media focused on microneedling and radiofrequency microneedling, this review aims to focus on the available high-quality evidence.

Methods

A comprehensive review of the literature was performed across PubMed (National Institutes of Health, Bethesda, MD) and Embase (Elsevier, Amsterdam, the Netherlands) databases. Attention was focused on manuscripts that provided objective data with respect to clinical application, innovation, anatomy, and physiology.

Results

Optimal outcomes are achieved when needle depth is targeted to the reticular dermis. Needle depth should reflect the relative differences in epidermal and dermal thickness throughout the face. A depth of at least 1.5 mm should be used for the forehead and temporal skin, 1.0 mm for the malar region, 2.0 mm (maximum depth for radiofrequency microneedling) for the nasal side walls, 0.5 mm for the perioral skin, and 1.5 mm for the neck. Deeper settings can be used with care to provide some fat reduction in the submentum.

Conclusions

The authors find herein that radiofrequency microneedling is a safe adjunctive tool to surgical aesthetic procedures. The addition of radiofrequency poses an advance over traditional microneedling devices for skin tightening, with improvements in both safety and efficacy over time.

Level of Evidence 5

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.

Microneedles for advanced ocular drug delivery

In the field of ocular drug delivery, topical delivery remains the most common treatment option for managing anterior segment diseases, whileintraocular injectionsare the current gold standard treatment option for treating posterior segment diseases. Nonetheless, topical eye drops are associated with low bioavailability (<5%), and theintravitreal administration procedure is highly invasive, yielding poor patient acceptability. In both cases, frequent administration is currently required. As a result, there is a clear unmet need for sustained drug delivery to the eye, particularly in a manner that can be localised. Microneedles, which are patches containing an array of micron-scale needles (<1 mm), have the potential to meet this need. These platforms can enable localised drug delivery to the eye while enhancing penetration of drug molecules through key ocular barriers, thereby improving overall therapeutic outcomes. Moreover, the minimally invasive manner in which microneedles are applied could provide significant advantages over traditional intravitreal injections regarding patient acceptability. Considering the benefitsofthis novel ocular delivery system, this review provides an in-depth overviewofthe microneedle systems for ocular drug delivery, including the types of microneedles used and therapeutics delivered. Notably, we outline and discuss the current challenges associated with the clinical translation of these platforms and offer opinions on factors which should be considered to improve such transition from lab to clinic.

Fabrication and characterisation of poly(sulfonated) and poly(sulfonic acid) dissolving microneedles for delivery of antibiotic and antifungal agents

Skin and soft tissue infections (SSTIs) arise from microbial ingress into the skin. In this study, poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (polyAMPS), which has been reported to exhibit antimicrobial properties was synthesised for the manufacture of microarray patches (MAPs). The free acid and sodium salt of polyAMPS with controlled molar masses and narrow dispersity were synthesised via reversible addition - fragmentation chain-transfer (RAFT) polymerisation reaction with a monomer conversion of over 99%, as determined by 1H NMR. The polymers were shown to be biocompatible when evaluated using a fibroblast dermal cell line while agar plating assay using cultures of C. albican demonstrated that the acid form of polyAMPS exhibited antimicrobial inhibition, which is potentiated in the presence of antimicrobial agents. The synthesised polymers were then used to fabricate dissolving MAPs, which were loaded with either ITRA or levofloxacin (LEV). The MAPs displayed acceptable mechanical resistance and punctured ex vivo skin to a depth of 600 µm. Skin deposition studies revealed that the MAPs were able to administer up to ∼ 1.9 mg of LEV (delivery efficiency: 94.7%) and ∼ 0.2 mg of ITRA (delivery efficiency: 45.9%), respectively. Collectively, the synthesis and development of this novel pharmaceutical system may offer a strategy to manage SSTIs.

Going below and beyond the surface: Microneedle structure, materials, drugs, fabrication, and applications for wound healing and tissue regeneration

Microneedle, as a novel drug delivery system, has attracted widespread attention due to its non-invasiveness, painless and simple administration, controllable drug delivery, and diverse cargo loading capacity. Although microneedles are initially designed to penetrate stratum corneum of skin for transdermal drug delivery, they, recently, have been used to promote wound healing and regeneration of diverse tissues and organs and the results are promising. Despite there are reviews about microneedles, few of them focus on wound healing and tissue regeneration. Here, we review the recent advances of microneedles in this field. We first give an overview of microneedle system in terms of its potential cargos (e.g., small molecules, macromolecules, nucleic acids, nanoparticles, extracellular vesicle, cells), structural designs (e.g., multidrug structures, adhesive structures), material selection, and drug release mechanisms. Then we briefly summarize different microneedle fabrication methods, including their advantages and limitations. We finally summarize the recent progress of microneedle-assisted wound healing and tissue regeneration (e.g., skin, cardiac, bone, tendon, ocular, vascular, oral, hair, spinal cord, and uterine tissues). We expect that our article would serve as a guideline for readers to design their microneedle systems according to different applications, including material selection, drug selection, and structure design, for achieving better healing and regeneration efficacy.

Development of a Microfluidic Formatted Ultrasound-Controlled Monodisperse Lipid Vesicles' Hydrogel Dressing Combined with Ultrasound for Transdermal Drug Delivery System

Transdermal drug delivery system (TDDS) has attracted much attention in the pharmaceutical technology area. However, the current methods are difficult to ensure penetration efficiency, controllability, and safety in the dermis, so its widespread clinical use has been limited. This work proposes an ultrasound-controlled monodisperse lipid vesicles (U-CMLVs) hydrogel dressing, which combines with ultrasound to form TDDS. Using microfluidic technology, prepare size controllable U-CMLVs with high drug encapsulation efficiency and quantitative encapsulation of ultrasonic response materials, and even uniform mix them with hydrogel to prepare the required thickness of dressings. The high encapsulation efficiency can ensure sufficient dosage of the drugs and further realize the control of ultrasonic response through quantitative encapsulation of ultrasound-responsive materials. Using high frequency (5 MHz, 0.4 W cm-2 ) and low frequency (60 kHz, 1 W cm-2 ) ultrasound to control the movement and rupture of U-CMLVs, the contents not only penetrate the stratum corneum into the epidermis but also break through the bottleneck of penetration efficiency, and deep into the dermis. These findings provide the groundwork for deep, controllable, efficient, and safe drug delivery through TDDS and lay a foundation for further expanding its application.

A Needle-Free Transdermal Patch for Sampling Interstitial Fluid

OBJECTIVE

Modern diagnostics is pivoting towards less invasive health monitoring in dermal interstitial fluid, rather than blood or urine. However, the skin's outermost layer, the stratum corneum, makes accessing the fluid more difficult without invasive, needle-based technology. Simple, minimally invasive means for surpassing this hurdle are needed.

METHODS

To address this problem, a flexible, Band-Aid-like patch for sampling interstitial fluid was developed and tested. This patch uses simple resistive heating elements to thermally porate the stratum corneum, allowing the fluid to exude from the deeper skin tissue without applying external pressure. Fluid is then transported to an on-patch reservoir through self-driving hydrophilic microfluidic channels.

RESULTS

Testing with living, ex-vivo human skin models demonstrated the device's ability to rapidly collect sufficient interstitial fluid for biomarker quantification. Further, finite-element modeling showed that the patch can porate the stratum corneum without raising the skin's temperature to pain-inducing levels in the nerve-laden dermis.

CONCLUSION

Relying only on simple, commercially scalable fabrication methods, this patch outperforms the collection rate of various microneedle-based patches, painlessly sampling a human bodily fluid without entering the body.

SIGNIFICANCE

The technology holds potential as a clinical device for an array of biomedical applications, especially with the integration of on-patch testing.

Delivery of gold nanoparticle-conjugated M2e influenza vaccine in mice using coated microneedles

As a prospective influenza vaccination platform, a microneedle patch offers advantages such as self-administration and reduction of needle-phobia-associated vaccination avoidance. In an effort to design a broadly protective influenza vaccine we have previously developed a vaccine formulation containing the highly conserved ectodomain sequence of the M2 influenza protein (M2e) attached to the surface of gold nanoparticles (AuNPs) with CpG as a soluble adjuvant (AuNP-M2e + sCpG). Our previous studies have used the intranasal route for vaccination and demonstrated broad protection from this vaccine. Here we asked the question whether the same formulation can be effective when administered to mice using microneedles. We demonstrate that the microneedles can be coated with AuNP-M2e + sCpG formulation, and the AuNPs from the coating can be readily resuspended without aggregation. The AuNPs were delivered with high efficiency into murine skin, and the AuNPs cleared the skin within 12 h of microneedle treatment. After vaccination, strong M2e-specific humoral and cellular responses were stimulated, and the vaccinated mice were 100% protected following a lethal challenge with influenza A/PR/8/34 (H1N1).

Industrial perspectives for personalized microneedles

Microneedles and, subsequently, microneedle arrays are emerging miniaturized medical devices for painless transdermal drug delivery. New and improved additive manufacturing methods enable novel microneedle designs to be realized for preclinical and clinical trial assessments. However, current literature reviews suggest that industrial manufacturers and researchers have focused their efforts on one-size-fits-all designs for transdermal drug delivery, regardless of patient demographic and injection site. In this perspective article, we briefly review current microneedle designs, microfabrication methods, and industrialization strategies. We also provide an outlook where microneedles may become personalized according to a patient's demographic in order to increase drug delivery efficiency and reduce healing times for patient-centric care.

Poly(2-Hydroxyethyl Methacrylate) Hydrogel-Based Microneedles for Metformin Release

The release of metformin, a drug used in the treatment of cancer and diabetes, from poly(2-hydroxyethyl methacrylate), pHEMA, hydrogel-based microneedle patches is demonstrated in vitro. Tuning the composition of the pHEMA hydrogels enables preparation of robust microneedle patches with mechanical properties such that they would penetrate skin (insertion force of a single microneedle to be ≈40 N). Swelling experiments conducted at 20, 35, and 60 °C show temperature-dependent degrees of swelling and diffusion kinetics. Drug release from the pHEMA hydrogel-based microneedles is fitted to various models (e.g., zero order, first order, second order). Such pHEMA microneedles have potential application for transdermal delivery of metformin for the treatment of aging, cancer, diabetes, etc.

Microneedles and Their Application in Transdermal Delivery of Antihypertensive Drugs-A Review

One of the most cutting-edge, effective, and least invasive pharmaceutical innovations is the utilization of microneedles (MNs) for drug delivery, patient monitoring, diagnostics, medicine or vaccine delivery, and other medical procedures (e.g., intradermal vaccination, allergy testing, dermatology, and blood sampling). The MN-based system offers many advantages, such as minimal cost, high medical effectiveness, comparatively good safety, and painless drug application. Drug delivery through MNs can possibly be viewed as a viable instrument for various macromolecules (e.g., proteins, peptides, and nucleic acids) that are not efficiently administered through traditional approaches. This review article provides an overview of MN-based research in the transdermal delivery of hypertensive drugs. The critical attributes of microneedles are discussed, including the mechanism of drug release, pharmacokinetics, fabrication techniques, therapeutic applications, and upcoming challenges. Furthermore, the therapeutic perspective and improved bioavailability of hypertensive drugs that are poorly aqueous-soluble are also discussed. This focused review provides an overview of reported studies and the recent progress of MN-based delivery of hypertensive drugs, paving the way for future pharmaceutical uses. As MN-based drug administration bypasses first-pass metabolism and the high variability in drug plasma levels, it has grown significantly more important for systemic therapy. In conclusion, MN-based drug delivery of hypertensive drugs for increasing bioavailability and patient compliance could support a new trend of hypertensive drug delivery and provide an alternative option, overcoming the restrictions of the current dosage forms.

Revolutionizing Precision Medicine: Exploring Wearable Sensors for Therapeutic Drug Monitoring and Personalized Therapy

Precision medicine, particularly therapeutic drug monitoring (TDM), is essential for optimizing drug dosage and minimizing toxicity. However, current TDM methods have limitations, including the need for skilled operators, patient discomfort, and the inability to monitor dynamic drug level changes. In recent years, wearable sensors have emerged as a promising solution for drug monitoring. These sensors offer real-time and continuous measurement of drug concentrations in biofluids, enabling personalized medicine and reducing the risk of toxicity. This review provides an overview of drugs detectable by wearable sensors and explores biosensing technologies that can enable drug monitoring in the future. It presents a comparative analysis of multiple biosensing technologies and evaluates their strengths and limitations for integration into wearable detection systems. The promising capabilities of wearable sensors for real-time and continuous drug monitoring offer revolutionary advancements in diagnostic tools, supporting personalized medicine and optimal therapeutic effects. Wearable sensors are poised to become essential components of healthcare systems, catering to the diverse needs of patients and reducing healthcare costs.

Microneedles for oral mucosal delivery - Current trends and perspective on future directions

INTRODUCTION

Oral cavity drug and vaccine delivery has the potential for local targeting, dose reduction, minimization of systemic side effects, and generation of mucosal immunity. To overcome current limitations of delivery into the oral cavity mucosa, microneedles (MNs) have emerged as a promising technology.

AREAS COVERED

We reviewed the literature on MN application in the oral cavity, including in vitro studies, in vivo animal studies, and human clinical trials.

EXPERT OPINION

MNs are sufficiently robust to cross the oral cavity epithelium and nearly painless when applied to different parts of the human oral mucosa including the lip, cheek, tongue, and palate. In recent years, MNs have been evaluated for different applications, including vaccination, topical anesthetic delivery, and treatment of local oral pathologies such as oral lesions or carcinomas. MNs are attractive because they have the potential to produce a better treatment outcome with reduced side effects. Over the coming years, we project a significant increase in research related to the development of MNs for use in dentistry and other medical conditions of the mouth.

Challenges and opportunities in delivering oral peptides and proteins

INTRODUCTION

Rapid advances in bioengineering enable the use of complex proteins as therapeutic agents to treat diseases. Compared with conventional small molecule drugs, proteins have multiple advantages, including high bioactivity and specificity with low toxicity. Developing oral dosage forms with active proteins is a route to improve patient compliance and significantly reduce production costs. However, the gastrointestinal environment remains a challenge to this delivery path due to enzymatic degradation, low permeability, and weak absorption, leading to reduced delivery efficiency and poor clinical outcomes.

AREAS COVERED

This review describes the barriers to oral delivery of peptides and complex proteins, current oral delivery strategies utilized and the opportunities and challenges ahead to try and circumvent these barriers. Oral protein drugs on the market and clinical trials provide insights and approaches for advancing delivery strategies.

EXPERT OPINION

Although most current studies on oral protein delivery rely on in vitro and in vivo animal data, the safety and limitations of the approach in humans remain uncertain. The shortage of clinical data limits the development of new or alternative strategies. Therefore, designing appropriate oral delivery strategies remains a significant challenge and requires new ideas, innovative design strategies and novel model systems.

The use of cellulose, chitosan and hyaluronic acid in transdermal therapeutic management of obesity: A review

Obesity is a clinical condition with rising popularity and detrimental impacts on human health. According to the World Health Organization, obesity is the sixth most common cause of death worldwide. It is challenging to combat obesity because medications that are successful in the clinical investigation have harmful side effects when administered orally. The conventional approaches for treating obesity primarily entail synthetic compounds and surgical techniques but possess severe adverse effects and recurrences. As a result, a safe and effective strategy to combat obesity must be initiated. Recent studies have shown that biological macromolecules of the carbohydrate class, such as cellulose, hyaluronic acid, and chitosan, can enhance the release and efficacy of medications for obesity but due to their short biological half-lives and poor oral bioavailability, their distribution rate is affected. This helps to comprehend the need for an effective therapeutic approach via a transdermal drug delivery system. This review focuses on the transdermal administration, utilizing cellulose, chitosan, and hyaluronic acid via microneedles, as it offers a promising solution to overcome existing therapy limitations in managing obesity and it also highlights how microneedles can effectively deliver therapeutic substances through the skin's outer layer, bypassing pain receptors and specifically targeting adipose tissue.

Tissue adhesive hemostatic microneedle arrays for rapid hemorrhage treatment

Blood loss by hemorrhaging wounds accounts for over one-third of ∼5 million trauma fatalities worldwide every year. If not controlled in a timely manner, exsanguination can take lives within a few minutes. Developing new biomaterials that are easy to use by non-expert patients and promote rapid blood coagulation is an unmet medical need. Here, biocompatible, and biodegradable microneedle arrays (MNAs) based on gelatin methacryloyl (GelMA) biomaterial hybridized with silicate nanoplatelets (SNs) are developed for hemorrhage control. The SNs render the MNAs hemostatic, while the needle-shaped structure increases the contact area with blood, synergistically accelerating the clotting time from 11.5 min to 1.3 min in vitro. The engineered MNAs reduce bleeding by ∼92% compared with the untreated injury group in a rat liver bleeding model. SN-containing MNAs outperform the hemostatic effect of needle-free patches and a commercial hemostat in vivo via combining micro- and nanoengineered features. Furthermore, the tissue adhesive properties and mechanical interlocking support the suitability of MNAs for wound closure applications. These hemostatic MNAs may enable rapid hemorrhage control, particularly for patients in developing countries or remote areas with limited or no immediate access to hospitals.

Exploring new frontiers in drug delivery with minimally invasive microneedles: fabrication techniques, biomedical applications and regulatory aspects

INTRODUCTION

Transdermal drug delivery is limited by the stratum corneum, inhibiting the therapeutic potential of the permeants. Microneedles (MN) have opened new frontiers in transdermal drug delivery systems. These micro-sized needles offer painless and accentuated delivery of drugs even with high molecular weights.

AREAS COVERED

The review embodies drug delivery strategies with microneedles with a description of MN types and fabrication techniques using various materials. The application of MN is not limited to drug delivery, but it also encompasses in vaccine delivery, diagnosis, phlebotomy and even in the cosmetic industry. The review also tabulates microneedle-based marketed formulations. In a nutshell, we aim to present a panoramic view of microneedles including the design, applications, and regulatory aspects of MN.

EXPERT OPINION

With the availability of numerous materials at the disposal of pharmaceutical scientists; the microneedle-based drug delivery technology has offered significant interventions towards the management of chronic maladies including cardiovascular disorders, diabetes, asthma, mental depression, etc. As happens with any new technology there are concerns with MN also such as biocompatibility issues with the material used for the fabrication. Nevertheless, the pharmaceutical industry must strive for preparing harmless, efficient, and cost-effective MN based delivery systems for wider acceptance and patient compliance.

Quantification methods comparing in vitro and in vivo percutaneous permeation by microneedles and passive diffusion

Microneedles (MNs) are needles with a tip diameter ranging from 10 to 100 um and a length ranging up to 1 mm. The first patent for drug delivery device for percutaneous administration filed by Alza corporation dates back to 1976 (Gerstel and Place, 1976), and in between 1989 and 2021 the filed patents for MNs are more than 4500 (Banks et al., 2010). These devices can potential overcome some drawbacks of traditional needles, such as the pain generated during insertion, requirement for trained personnel to manipulate syringes, and difficulty of performing injections in elderly and obese patients. MNs and MNs arrays are emerging as a convenient method to deliver compounds and extract blood without causing any pain. A promising application is the use of MNs as alternative solution to topical creams (TC) and transdermal patches (TP) for transdermal drug delivery. The external layer of human skin, the epidermis, offers a major barrier to transdermal drug delivery, thanks to the stratum corneum (SC). Exposed to the external environment, SC ultimately protects the human body from UV light radiation, heat, water loss, bacteria, fungi and viruses, and it is the barrier that controls diffusion rate for almost all compounds. TC and TP applications are limited by the skin permeability to lipophilic compounds and small molecules, and by the slow delivery rate of some compounds. MNs have been around for more than 35 year now, and it is a general opinion that MN increase delivery compared to passive diffusion, thanks to the feature of penetrating the SC and reaching the dermis. This review recollects the existing studies that compare MNs delivery of drugs with passive diffusion of the same drugs in alive organisms, giving an overview of what are the type of MNs, the chemical delivered and the methods employed to quantify drug delivery into skin and/or in the bloodstream. The final aim is to quantify the enhancement factor of MNs with respect to passive diffusion, and establish a possible standard on how tests can be performed in order to compare different data.