Biodegradable polymeric insulin microneedles - a design and materials perspective review

Biodegradable sustained-release microneedle patch loaded with clindamycin hydrochloride: a breakthrough in acne management

Background

Clindamycin hydrochloride, a first-line antibiotic for acne treatment, faces challenges with poor skin penetration due to its hydrophilicity and the barrier posed by the stratum corneum. To address this limitation, we developed gelatin-methacryloyl (GelMA) hydrogel-based biodegradable microneedles (GM-Clin-MN) for sustained intradermal drug delivery, thereby enhancing therapeutic efficacy.

Methods

The microneedle patches loaded with 1 wt% clindamycin hydrochloride were fabricated using PDMS molds and characterized through scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and fluorescence microscopy. Drug loading and release were assessed using UV-Vis spectroscopy at 520 nm, while mechanical strength was evaluated with a universal testing machine. Skin penetration was tested on ex vivo rat abdominal skin. Biosafety was determined through human skin fibroblast (HSF) cytotoxicity and hen's egg test-chorioallantoic membrane (HET-CAM) irritation tests. Antibacterial efficacy against Cutibacterium acnes (C. acnes) was measured via colony counting. In vivo acne treatment of the microneedles was evaluated in a rat acne model. Gross morphological changes, histological sections, and immunohistochemical staining were used to evaluate the efficacy and potential mechanisms of acne treatment.

Results

Clindamycin hydrochloride-loaded GelMA microneedles (GM-Clin-MN) achieved a drug loading of 0.49 ± 0.025 μg/needle, exhibiting rapid release on Day 1 (54.8% ± 2.1%) and sustained release by Day 10 (72.1% ± 1.5%). The microneedles penetrated the skin to a depth of 658 ± 66 μm, swelled by 185.4% ± 12.1%, and completely dissolved within 10 min. GM-Clin-MN displayed no cytotoxicity or skin irritation and effectively inhibited the growth of C. acnes (bacterial inhibition rate of 100%). In vivo studies revealed that acne-related inflammation was effectively suppressed with potential anti-scarring properties, characterized by reduced pro-inflammatory IL-1β levels, increased anti-inflammatory IL-10 expression, and diminished MMP-2 activity - a key enzyme in collagen overproduction during scarring.

Conclusion

GM-Clin-MN enables sustained, minimally invasive clindamycin delivery through the stratum corneum, offering a dual-action therapeutic strategy that combines potent antibacterial activity with anti-inflammatory modulation for acne management.

A review on microneedle patch as a delivery system for proteins/peptides and their applications in transdermal inflammation suppression

Transdermal delivery is one of the most recent modes of administration studied due to several shortfalls observed for intra-venous, and oral drug administrations. Among, microneedle-based transdermal delivery is the popular choice due to non-invasive procedure and minimal toxicological effects. Microneedle devices consist of micron scaled needle patch entrapped with the target specific drug molecules. Due to body's immune response and occasional pathogen attack, various inflammatory diseases are developed such as psoriasis, dermatitis, rashes, rheumatoid arthritis, gouty arthritis, and fibrosis. These inflammatory conditions can be treated by microneedle assisted transdermal delivery. Moreover, for localized suppression of pain and inflammation, various therapeutic peptides and proteins have been investigated. Although, these therapeutic agents can show reduced activity and undergo enzymatic degradation when administered orally or intra-venously. Hence, a microneedle-based delivery system can be used as an effective way to localize these peptides/proteins and reduce the inflammation. Herein, this review includes various microneedle fabrication methods for enhancing drug delivery for suppression of inflammation. Moreover, recent development in microneedle devices of peptide and protein delivery applications are discoursed. At last, future scope and challenges endured for preparing an efficient microneedle patch for peptide and protein delivery are also elaborated.

The Third Pillar of Precision Medicine - Precision Delivery

Precision Medicine is thought of as having two main pillars: Precision Diagnosis and Precision Therapy. However, for Precision Medicine to reach its full potential, a third pillar is needed that we propose to call Precision Delivery. In the laboratory, many therapies show great efficacy when tested directly with target cells. However, upon clinical translation, they are often given via intravenous or oral administration, resulting in their systemic distribution. To ensure therapies reach target sites at the correct therapeutic levels, they are often given at higher concentrations. However, this can be associated with off-target effects, side-effects, and unwanted interactions. Delivery strategies can help mitigate this by "spatially re-coupling" therapies in vivo with target cells. This review explains the concept of Precision Delivery, which can be thought of as three interconnected, but independent, modules: targeted delivery, microenvironment modulation, and cellular interactions. While locoregional approaches directly deliver therapies into target tissues through endovascular, endoluminal, percutaneous, and implantation techniques, microenvironment modulation technologies facilitate the movement of therapies across biological barriers and through tissue matrices, so optimized therapies can reach and interact with target cells. We highlight new innovations driving advances in Precision Delivery, while also discussing the considerations and challenges that Precision Delivery faces as it becomes increasingly integrated into treatment workflows.

Unique advantages and applications of polysaccharide microneedles as drug delivery materials and in treatment of skin diseases

Owing to its non-invasive nature, painless drug delivery, and controlled drug loading capacity, the microneedle (MN) technology has recently garnered significant attention in clinical practice. For instance, it has been pervasively employed as an innovative transdermal delivery method in skin disease therapy. However, traditional MN techniques have been associated with challenges regarding biocompatibility, biodegradability, and drug release precision, limiting their clinical efficacy and increasing the risk of side effects resulting from uneven drug distribution. To address these issues, polysaccharide materials have been proposed as viable alternatives to be used in MN technologies. In addition to their excellent biocompatibility and biodegradability, polysaccharide materials such as alginate, chitosan, and Hyaluronic Acid (HA), among other Traditional Chinese Medicine (TCM)-extracted polysaccharides (such as Bletilla and notoginseng), could also exert anti-inflammatory and antibacterial effects, promoting tissue regeneration. These attributes enable polysaccharide-based MNs to improve the local drug concentration, reduce systemic side effects, minimize patient discomfort, and lower treatment risks, making them particularly suitable for treating skin conditions such as eczema, psoriasis, and acne. This article systematically reviews the properties of various polysaccharide materials, as well as the preparation methods of polysaccharide-based MNs and their therapeutic effects as reported in animal models and clinical trials. Our findings could lay a solid theoretical foundation for developing polysaccharide-based MN technologies and fostering their widespread clinical application.

Graphene-Based Polymeric Microneedles for Biomedical Applications: A Comprehensive Review

Transdermal drug delivery presents a promising noninvasive approach, bypassing first-pass metabolism and gastrointestinal degradation. However, the stratum corneum (SC) barrier limits drug absorption, necessitating the development of effective delivery systems. Microneedles, particularly polymer-based ones, offer a solution by penetrating the SC while avoiding critical nerves and capillaries. These microneedles are biodegradable, nontoxic, and easily manufacturable, making them a highly attractive platform for transdermal drug delivery. However, their clinical application remains limited due to suboptimal therapeutic efficacy and slow drug release rates. Recent advancements have introduced the incorporation of nanodrugs, such as nanoparticles and encapsulated drugs, into microneedles to enhance drug delivery efficiency. Among the materials explored, graphene and its derivatives, including graphene oxide (GO) and reduced graphene oxide (rGO), have garnered significant attention. Their exceptional mechanical strength, electrical conductivity, and antibacterial properties not only improve the mechanical performance of microneedles but also enhance drug release rates and biocompatibility. This review synthesizes the current state of microneedle technologies, focusing on the materials, fabrication techniques, and performance challenges. It particularly examines the potential of graphene-based microneedles, comparing them to traditional polymer-based microneedles in terms of drug release efficiency and stability. The review highlights key challenges, such as scalability, biocompatibility, and fabrication complexity, and suggests future research directions to address these issues. The incorporation of graphene quantum dots (GQDs) is identified as a promising avenue for improving drug release profiles, stability, and real-time tracking of drug diffusion. Finally, the review outlines emerging applications, including smart drug delivery systems, biosensing, and real-time monitoring, urging further exploration to unlock the full potential of graphene-enhanced microneedles in clinical settings.

Applications and prospects of biomaterials in diabetes management

Diabetes is a widespread metabolic disorder that presents considerable challenges in its management. Recent advancements in biomaterial research have shed light on innovative approaches for the treatment of diabetes. This review examines the role of biomaterials in diabetes diagnosis and treatment, as well as their application in managing diabetic wounds. By evaluating recent research developments alongside future obstacles, the review highlights the promising potential of biomaterials in diabetes care, underscoring their importance in enhancing patient outcomes and refining treatment methodologies.

Recent Advances in Degradable Biomedical Polymers for Prevention, Diagnosis and Treatment of Diseases

Biomedical polymers play a key role in preventing, diagnosing, and treating diseases, showcasing a wide range of applications. Their unique advantages, such as rich source, good biocompatibility, and excellent modifiability, make them ideal biomaterials for drug delivery, biomedical imaging, and tissue engineering. However, conventional biomedical polymers suffer from poor degradation in vivo, increasing the risks of bioaccumulation and potential toxicity. To address these issues, degradable biomedical polymers can serve as an alternative strategy in biomedicine. Degradable biomedical polymers can efficiently relieve bioaccumulation in vivo and effectively reduce patient burden in disease management. This review comprehensively introduces the classification and properties of biomedical polymers and the recent research progress of degradable biomedical polymers in various diseases. Through an in-depth analysis of their classification, properties, and applications, we aim to provide strong guidance for promoting basic research and clinical translation of degradable biomedical polymers.

Nanomaterial-Enhanced Microneedles: Emerging Therapies for Diabetes and Obesity

Drug delivery systems (DDS) have improved therapeutic agent administration by enhancing efficacy and patient compliance while minimizing side effects. They enable targeted delivery, controlled release, and improved bioavailability. Transdermal drug delivery systems (TDDS) offer non-invasive medication administration and have evolved to include methods such as chemical enhancers, iontophoresis, microneedles (MN), and nanocarriers. MN technology provides innovative solutions for chronic metabolic diseases like diabetes and obesity using various MN types. For diabetes management, MNs enable continuous glucose monitoring, diabetic wound healing, and painless insulin delivery. For obesity treatment, MNs provide sustained transdermal delivery of anti-obesity drugs or nanoparticles (NPs). Hybrid systems integrating wearable sensors and smart materials enhance treatment effectiveness and patient management. Nanotechnology has advanced drug delivery by integrating nano-scaled materials like liposomes and polymeric NPs with MNs. In diabetes management, glucose-responsive NPs facilitate smart insulin delivery. At the same time, lipid nanocarriers in dissolving MNs enable extended release for obesity treatment, enhancing drug stability and absorption for improved metabolic disorder therapies. DDS for obesity and diabetes are advancing toward personalized treatments using smart MN enhanced with nanomaterials. These innovative approaches can enhance patient outcomes through precise drug administration and real-time monitoring. However, widespread implementation faces challenges in ensuring biocompatibility, improving technologies, scaling production, and obtaining regulatory approval. This review will present recent advances in developing and applying nanomaterial-enhanced MNs for diabetes and obesity management while also discussing the challenges, limitations, and future perspectives of these innovative DDS.

Nanoformulation-assisted microneedle transdermal drug delivery system: An innovative platform enhancing rheumatoid arthritis treatment

A transdermal delivery system offers high bioavailability and favorable patient adherence, constituting an optimal approach for localized administration in rheumatoid arthritis (RA) treatment. However, the stratum corneum (SC) impedes the delivery efficiency of conventional transdermal drug delivery systems. Microneedles (MNs) can temporarily create micropores within the SC, enabling drug distribution via bypassing this barrier and enhancing transdermal delivery effectiveness. Notably, MNs provide a painless method of drug delivery through the skin and may directly modulate inflammation in immune cells by delivering drugs via the lymphatic system during transdermal administration. However, the MN delivery system is not suitable for drugs with low water solubility and stability. Additionally, major concerns exist regarding the safety of using MN delivery for highly cytotoxic drugs, given that it could result in high local drug concentration at the delivery site. While MNs exhibit some degree of targeted delivery to the immune and inflammatory environment, their targeting efficiency remains suboptimal. Nanoformulations have the potential to significantly address the limitations of MNs in RA treatment by improving drug targeting, solubility, stability, and biocompatibility. Therefore, this review provides a concise overview of the advantages, disadvantages, and mechanisms of different types of MNs for RA treatment. It specifically focuses on the application and advantages of combining nanoformulation with MNs for RA treatment and summarizes the current trends in the development of nanoformulations combined with MNs in the field of RA treatment, offering theoretical support for future advancements and clinical applications.

Advances in Nanomedicine for Precision Insulin Delivery

Diabetes mellitus, which comprises a group of metabolic disorders affecting carbohydrate metabolism, is characterized by improper glucose utilization and excessive production, leading to hyperglycemia. The global prevalence of diabetes is rising, with projections indicating it will affect 783.2 million people by 2045. Insulin treatment is crucial, especially for type 1 diabetes, due to the lack of β-cell function. Intensive insulin therapy, involving multiple daily injections or continuous subcutaneous insulin infusion, has proven effective in reducing microvascular complications but poses a higher risk of severe hypoglycemia. Recent advancements in insulin formulations and delivery methods, such as ultra-rapid-acting analogs and inhaled insulin, offer potential benefits in terms of reducing hypoglycemia and improving glycemic control. However, the traditional subcutaneous injection method has drawbacks, including patient compliance issues and associated complications. Nanomedicine presents innovative solutions to these challenges, offering promising avenues for overcoming current drug limitations, enhancing cellular uptake, and improving pharmacokinetics and pharmacodynamics. Various nanocarriers, including liposomes, chitosan, and PLGA, provide protection against enzymatic degradation, improving drug stability and controlled release. These nanocarriers offer unique advantages, ranging from enhanced bioavailability and sustained release to specific targeting capabilities. While oral insulin delivery is being explored for better patient adherence and cost-effectiveness, other nanomedicine-based methods also show promise in improving delivery efficiency and patient outcomes. Safety concerns, including potential toxicity and immunogenicity issues, must be addressed, with the FDA providing guidance for the safe development of nanotechnology-based products. Future directions in nanomedicine will focus on creating next-generation nanocarriers with precise targeting, real-time monitoring, and stimuli-responsive features to optimize diabetes treatment outcomes and patient safety. This review delves into the current state of nanomedicine for insulin delivery, examining various types of nanocarriers and their mechanisms of action, and discussing the challenges and future directions in developing safe and effective nanomedicine-based therapies for diabetes management.

Is it advantageous to use quality by design (QbD) to develop nanoparticle-based dosage forms for parenteral drug administration?

Parenteral administration is one of the most commonly used drug delivery routes for nanoparticle-based dosage forms, such as lipid-based and polymeric nanoparticles. For the treatment of various diseases, parenteral administration include intravenous, subcutaneous, and intramuscular route. In drug development phase, multiparameter strategy with a focus on drug physicochemical properties and the specificity of the administration route is required. Nanoparticle properties in terms of size and targeted delivery, among others, are able to surpass many drawbacks of conventional dosage forms, but these unique properties can be a bottleneck for approval by regulatory authorities. Quality by Design (QbD) approach has been widely utilized in development of parenteral nanoparticle-based dosage forms. It fosters knowledge of product and process quality by involving sound scientific data and risk assessment strategies. A full and comprehensive investigation into the state of implementation and applications of the QbD approach in these complex drug products can highlight the gaps and challenges. In this review, the analysis of critical attributes and Design of Experiment (DoE) approach in different nanoparticulate systems, together with the proper utilization of Process Analytical Technology (PAT) applications are described. The essential of QbD approach for the design and development of nanoparticle-based dosage forms for delivery via parenteral routes is discussed thoroughly.

Polymeric Microneedles for Health Care Monitoring: An Emerging Trend

Bioanalyte collection by blood draw is a painful process, prone to needle phobia and injuries. Microneedles can be engineered to penetrate the epidermal skin barrier and collect analytes from the interstitial fluid, arising as a safe, painless, and effective alternative to hypodermic needles. Although there are plenty of reviews on the various types of microneedles and their use as drug delivery systems, there is a lack of systematization on the application of polymeric microneedles for diagnosis. In this review, we focus on the current state of the art of this field, while providing information on safety, preclinical and clinical trials, and market distribution, to outline what we believe will be the future of health monitoring.

Recent Insights into Glucose-Responsive Concanavalin A-Based Smart Hydrogels for Controlled Insulin Delivery

Many efforts are continuously undertaken to develop glucose-sensitive biomaterials able of controlling glucose levels in the body and self-regulating insulin delivery. Hydrogels that swell or shrink as a function of the environmental free glucose content are suitable systems for monitoring blood glucose, delivering insulin doses adapted to the glucose concentration. In this context, the development of sensors based on reversible binding to glucose molecules represents a continuous challenge. Concanavalin A (Con A) is a bioactive protein isolated from sword bean plants (Canavalia ensiformis) and contains four sugar-binding sites. The high affinity for reversibly and specifically binding glucose and mannose makes Con A as a suitable natural receptor for the development of smart glucose-responsive materials. During the last few years, Con A was used to develop smart materials, such as hydrogels, microgels, nanoparticles and films, for producing glucose biosensors or drug delivery devices. This review is focused on Con A-based materials suitable in the diagnosis and therapeutics of diabetes. A brief outlook on glucose-derived theranostics of cancer is also presented.

Minoxidil Nanosuspension-Loaded Dissolved Microneedles for Hair Regrowth

Minoxidil (MIN) is used topically to treat alopecia. However, its low absorption limits its use, warranting a new strategy to enhance its delivery into skin layers. The objective of this study was to evaluate the dermal delivery of MIN by utilizing dissolved microneedles (MNs) loaded with MIN nanosuspension (MIN-NS) for hair regrowth. MIN-NS was prepared by the solvent-antisolvent precipitation technique. The particle size of MIN-NS was 226.7 ± 9.3 nm with a polydispersity index of 0.29 ± 0.17 and a zeta potential of -29.97 ± 1.23 mV. An optimized formulation of MIN-NS was selected, freeze-dried, and loaded into MNs fabricated with sodium carboxymethyl cellulose (Na CMC) polymeric solutions (MIN-NS-loaded MNs). MNs were evaluated for morphology, dissolution rate, skin insertion, drug content, mechanical properties, ex vivo permeation, in vivo, and stability studies. MNs, prepared with 14% Na CMC, were able to withstand a compression force of 32 N for 30 s, penetrate Parafilm M® sheet at a depth of 374-504 µm, and dissolve completely in the skin within 30 min with MIN %recovery of 95.1 ± 6.5%. The release of MIN from MIN-NS-loaded MNs was controlled for 24 h. MIN-NS-loaded MNs were able to maintain their mechanical properties and chemical stability for 4 weeks, when kept at different storage conditions. The in vivo study of the freeze-dried MIN-NS and MIN-NS-loaded MNs proved hair regrowth on rat skin after 11 and 7 days, respectively. These results showed that MIN-NS-loaded MNs could potentially improve the dermal delivery of MIN through the skin to treat alopecia.

Recent progress of polymeric microneedle-assisted long-acting transdermal drug delivery

Microneedle (MN)-assisted drug delivery technology has gained increasing attention over the past two decades. Its advantages of self-management and being minimally invasive could allow this technology to be an alternative to hypodermic needles. MNs can penetrate the stratum corneum and deliver active ingredients to the body through the dermal tissue in a controlled and sustained release. Long-acting polymeric MNs can reduce administration frequency to improve patient compliance and therapeutic outcomes, especially in the management of chronic diseases. In addition, long-acting MNs could avoid gastrointestinal reactions and reduce side effects, which has potential value for clinical application. In this paper, advances in design strategies and applications of long-acting polymeric MNs are reviewed. We also discuss the challenges in scale manufacture and regulations of polymeric MN systems. These two aspects will accelerate the effective clinical translation of MN products.