Dissolving microneedle with high molecular weight hyaluronic acid to improve skin wrinkles, dermal density and elasticity

Microneedles Based on a Biodegradable Polymer-Hyaluronic Acid

Transdermal transport can be challenging due to the difficulty in diffusing active substances through the outermost layer of the epidermis, as the primary function of the skin is to protect against the entry of exogenous compounds into the body. In addition, penetration of the epidermis for substances hydrophilic in nature and particles larger than 500 Da is highly limited due to the physiological properties and non-polar nature of its outermost layer, namely the stratum corneum. A solution to this problem can be the use of microneedles, which "bypass" the problematic epidermal layer by dispensing the active substance directly into the deeper layers of the skin. Microneedles can be obtained with various materials and come in different types. Of special interest are carriers based on biodegradable and biocompatible polymers, such as polysaccharides. Therefore, this paper reviews the latest literature on methods to obtain hyaluronic acid-based microneedles. It focuses on the current advancements in this field and consequently provides an opportunity to guide future research in this area.

The promise of microneedle technologies for drug delivery

Microneedle (MN) technologies offer the opportunity to improve patient access and target delivery of drugs and vaccines to specific tissues. When in the form of skin patches, MNs can be administered by personnel with minimal training, or could be self-administered by patients, which can improve access to medication, especially those usually requiring injection. Because MNs are small (usually sub-millimetre), they can be used for precise tissue targeting. MN patches have been extensively studied to administer vaccines and drugs in preclinical work as well as in multiple clinical trials. When formulated with biodegradable polymer, MNs can enable long-acting therapies by slowly releasing drug as the MNs biodegrade. Targeted drug delivery by hollow MNs has resulted in FDA-approved products that are able to inject vaccines to skin-resident immune cells to improve immune response and to target specific parts of the eye (e.g., suprachoroidal space) for increased efficacy and avoidance of side effects in other parts of the eye. Cosmetic products based on MN technologies are already in widespread use, mostly as anti-aging agents. With extensive research coupled with FDA-approved products, MN technology promises to continue is growth in research leading to products that can benefit patients.

3D Printing of Biodegradable Polymeric Microneedles for Transdermal Drug Delivery Applications

Microneedle (MN) technology is an optimal choice for the delivery of drugs via the transdermal route, with a minimally invasive procedure. MN applications are varied from drug delivery, cosmetics, tissue engineering, vaccine delivery, and disease diagnostics. The MN is a biomedical device that offers many advantages including but not limited to a painless experience, being time-effective, and real-time sensing. This research implements additive manufacturing (AM) technology to fabricate MN arrays for advanced therapeutic applications. Stereolithography (SLA) was used to fabricate six MN designs with three aspect ratios. The MN array included conical-shaped 100 needles (10 × 10 needle) in each array. The microneedles were characterized using optical and scanning electron microscopy to evaluate the dimensional accuracy. Further, mechanical and insertion tests were performed to analyze the mechanical strength and skin penetration capabilities of the polymeric MN. MNs with higher aspect ratios had higher deformation characteristics suitable for penetration to deeper levels beyond the stratum corneum. MNs with both 0.3 mm and 0.4 mm base diameters displayed consistent force-displacement behavior during a skin-equivalent penetration test. This research establishes guidelines for fabricating polymeric MN for high-accuracy and low-cost 3D printing.

Fabrication Technology of Self-Dissolving Sodium Hyaluronate Gels Ultrafine Microneedles for Medical Applications with UV-Curing Gas-Permeable Mold

Microneedles are of great interest in diverse fields, including cosmetics, drug delivery systems, chromatography, and biological sensing for disease diagnosis. Self-dissolving ultrafine microneedles of pure sodium hyaluronate hydrogels were fabricated using a UV-curing TiO2-SiO2 gas-permeable mold polymerized by sol-gel hydrolysis reactions in nanoimprint lithography processes under refrigeration at 5 °C, where thermal decomposition of microneedle components can be avoided. The moldability, strength, and dissolution behavior of sodium hyaluronate hydrogels with different molecular weights were compared to evaluate the suitability of ultrafine microneedles with a bottom diameter of 40 μm and a height of 80 μm. The appropriate molecular weight range and formulation of pure sodium hyaluronate hydrogels were found to control the dissolution behavior of self-dissolving ultrafine microneedles while maintaining the moldability and strength of the microneedles. This fabrication technology of ultrafine microneedles expands their possibilities as a next-generation technique for bioactive gels for controlling the blood levels of drugs and avoiding pain during administration.

Drug Delivery Systems based on Microneedles for Dermatological Diseases and Aesthetic Enhancement

Microneedle (MN) devices comprise of micron-sized structures that circumvent biological barriers in a minimally invasive manner. MN research continues to grow and evolve; the technology was recently identified as one of the top ten overall emerging technologies of 2020. There is a growing interest in using such devices in cosmetology and dermatological conditions where the MNs mechanically disrupt the outer skin barrier layer, creating transient pathways that allow the passage of materials to underlying skin layers. This review aims to appraise the application of microneedle technologies in skin science, provide information on potential clinical benefits, as well as indicate possible dermatological conditions that can benefit from this technology, including autoimmunemediated inflammatory skin diseases, skin aging, hyperpigmentation, and skin tumors. A literature review was carried out to select studies that evaluated the use of microneedles to enhance drug delivery for dermatologic purposes. MN patches create temporary pathways that allow the passage of therapeutic material to deeper layers of the skin. Given their demonstrable promise in therapeutic applications it will be essential for healthcare professionals to engage with these new delivery systems as they transition to the clinic.

Clinical Assessment, Diagnosis, and Management of Infraorbital Wrinkles and Pigmentation

Lower eyelid skin is unique and different from that of other areas. In addition to being an area of high exposure to the sun and elements, there are anatomic considerations and specific histologic characteristics that can cause the skin in this area to be more sensitive. These attributes can readily cause under-eye wrinkling and pigmentation. This review aims to present an updated overview of the current knowledge regarding the clinical characteristics, diagnosis, and management of wrinkles and pigmentation in this area. These disorders are usually caused by different factors, such as genetics, aging, sun exposure, lack of sleep, and stress.

Tiny titans- unravelling the potential of polysaccharides and proteins based dissolving microneedles in drug delivery and theranostics: A comprehensive review

In recent years, microneedles (MNs) have emerged as a promising alternative to traditional drug delivery systems in transdermal drug delivery. The use of MNs has demonstrated significant potential in improving patient acceptance and convenience while avoiding the invasiveness of traditional injections. Dissolving, solid, hollow, coated, and hydrogel microneedles are among the various types studied for drug delivery. Dissolving microneedles (DMNs), in particular, have gained attention for their safety, painlessness, patient convenience, and high delivery efficiency. This comprehensive review primarily focuses on different types of microneedles, fabrication methods, and materials used in fabrication of DMNs such as hyaluronic acid, chitosan, alginate, gelatin, collagen, silk fibroin, albumin, cellulose and starch, to list a few. The review also provides an exhaustive discussion on the applications of DMNs, including the delivery of vaccines, cosmetic agents, contraceptives, hormone and genes, and other therapeutic applications like for treating cancer, skin diseases, and diabetes, among others, are covered in this review. Additionally, this review highlights some of the DMN systems that are presently undergoing clinical trials. Finally, the review discusses current advances and trends in DMNs, as well as future prospective directions for this ground-breaking technology in drug delivery.

Microencapsulation of alcohol solvents and high-content actives for efficient transdermal delivery

The barrier function of the skin in effectively protecting the underlying tissue from the surrounding environment makes it challenging to achieve the efficient transdermal delivery of actives. Herein, we report on alcohol-solvent-encapsulated microcapsules to achieve enhanced skin efficacy. We show that using palm oil as the shell material allows for the microencapsulation of a broad range of alcohol solvents, including ethanol and dipropylene glycol (DPG), as well as on-demand release. Moreover, clinical trials reveal that the high-content actives in microcapsules result in enhanced skin efficacy, and the presence of DPG effectively mediates the transdermal delivery of these actives without causing any skin irritation. We envision that the alcohol-solvent microencapsulation strategy outlined in this work offers new possibilities in cosmetics, food, and drug delivery systems.

Dissolving and Swelling Hydrogel-Based Microneedles: An Overview of Their Materials, Fabrication, Characterization Methods, and Challenges

Polymeric hydrogels are a complex class of materials with one common feature-the ability to form three-dimensional networks capable of imbibing large amounts of water or biological fluids without being dissolved, acting as self-sustained containers for various purposes, including pharmaceutical and biomedical applications. Transdermal pharmaceutical microneedles are a pain-free drug delivery system that continues on the path to widespread adoption-regulatory guidelines are on the horizon, and investments in the field continue to grow annually. Recently, hydrogels have generated interest in the field of transdermal microneedles due to their tunable properties, allowing them to be exploited as delivery systems and extraction tools. As hydrogel microneedles are a new emerging technology, their fabrication faces various challenges that must be resolved for them to redeem themselves as a viable pharmaceutical option. This article discusses hydrogel microneedles from a material perspective, regardless of their mechanism of action. It cites the recent advances in their formulation, presents relevant fabrication and characterization methods, and discusses manufacturing and regulatory challenges facing these emerging technologies before their approval.

Hyaluronic Acid-Extraction Methods, Sources and Applications

In this review, a compilation of articles in databases on the extraction methods and applications of hyaluronic acid (HA) was carried out. HA is a highly hydrated component of different tissues, including connective, epithelial, and neural. It is an anionic, linear glycosaminoglycan (GAG) primarily found in the native extracellular matrix (ECM) of soft connective tissues. Included in the review were studies on the extraction methods (chemical, enzymatical, combined) of HA, describing advantages and disadvantages as well as news methods of extraction. The applications of HA in food are addressed, including oral supplementation, biomaterials, medical research, and pharmaceutical and cosmetic industry applications. Subsequently, we included a section related to the structure and penetration routes of the skin, with emphasis on the benefits of systems for transdermal drug delivery nanocarriers as promoters of percutaneous absorption. Finally, the future trends on the applications of HA were included. This final section contains the effects before, during, and after the application of HA-based products.

Flexible Monitoring, Diagnosis, and Therapy by Microneedles with Versatile Materials and Devices toward Multifunction Scope

Microneedles (MNs) have drawn rising attention owing to their merits of convenience, noninvasiveness, flexible applicability, painless microchannels with boosted metabolism, and precisely tailored multifunction control. MNs can be modified to serve as novel transdermal drug delivery, which conventionally confront with the penetration barrier caused by skin stratum corneum. The micrometer-sized needles create channels through stratum corneum, enabling efficient drug delivery to the dermis for gratifying efficacy. Then, incorporating photosensitizer or photothermal agents into MNs can conduct photodynamic or photothermal therapy, respectively. Besides, health monitoring and medical detection by MN sensors can extract information from skin interstitial fluid and other biochemical/electronic signals. Here, this review discloses a novel monitoring, diagnostic, and therapeutic pattern by MNs, with elaborate discussion about the classified formation of MNs together with various applications and inherent mechanism. Hereby, multifunction development and outlook from biomedical/nanotechnology/photoelectric/devices/informatics to multidisciplinary applications are provided. Programmable intelligent MNs enable logic encoding of diverse monitoring and treatment pathways to extract signals, optimize the therapy efficacy, real-time monitoring, remote control, and drug screening, and take instant treatment.

Comprehensive review on biosynthesis of hyaluronic acid with different molecular weights and its biomedical applications

Hyaluronic acid (HA), an anionic and nonsulfated glycosaminoglycan, is the main structural component of various tissues and plays an important role in various biological processes. Given the promising properties of HA, such as high cellular compatibility, moisture retention, antiaging, proper interaction with cells, and CD44 targeting, HA can be widely used extensively in drug delivery, tissue engineering, wound healing, and cancer therapy. HA can obtain from animal tissues and microbial fermentation, but its applications depend on its molecular weight. Microbial fermentation is a common method for HA production on an industrial scale and S. zooepidemicus is the most frequently used strain in HA production. Culture conditions including pH, temperature, agitation rate, aeration speed, shear stress, dissolved oxygen, and bioreactor type significantly affect HA biosynthesis properties. In this review all the HA production methods and purification techniques to improve its physicochemical and biological properties for various biomedical applications are discussed in details. In addition, we showed that how HA molecular weight can significantly affect its properties and applications.

Marine Natural Products as Innovative Cosmetic Ingredients

Over the course of the last 20 years, numerous studies have identified the benefits of an array of marine natural ingredients for cosmetic purposes, as they present unique characteristics not found in terrestrial organisms. Consequently, several marine-based ingredients and bioactive compounds are under development, used or considered for skin care and cosmetics. Despite the multitude of cosmetics based on marine sources, only a small proportion of their full potential has been exploited. Many cosmetic industries have turned their attention to the sea to obtain innovative marine-derived compounds for cosmetics, but further research is needed to determine and elucidate the benefits. This review gathers information on the main biological targets for cosmetic ingredients, different classes of marine natural products of interest for cosmetic applications, and the organisms from which such products can be sourced. Although organisms from different phyla present different and varied bioactivities, the algae phylum seems to be the most promising for cosmetic applications, presenting compounds of many classes. In fact, some of these compounds present higher bioactivities than their commercialized counterparts, demonstrating the potential presented by marine-derived compounds for cosmetic applications (i.e., Mycosporine-like amino acids and terpenoids’ antioxidant activity). This review also summarizes the major challenges and opportunities faced by marine-derived cosmetic ingredients to successfully reach the market. As a future perspective, we consider that fruitful cooperation among academics and cosmetic industries could lead to a more sustainable market through responsible sourcing of ingredients, implementing ecological manufacturing processes, and experimenting with inventive recycling and reuse programs.

3D Printed Hollow Microneedles for Treating Skin Wrinkles Using Different Anti-Wrinkle Agents: A Possible Futuristic Approach

Skin wrinkles are an inevitable phenomenon that is brought about by aging due to the degradation of scleroprotein fibers and significant collagen reduction, which is the fundamental basis of anti-wrinkle technology in use today. Conventional treatments such as lasering and Botulinum toxin have some drawbacks including allergic skin reactions, cumbersome treatment procedures, and inefficient penetration of the anti-wrinkle products into the skin due to the high resistance of stratum corneum. Bearing this in mind, the cosmetic industry has exploited the patient-compliant technology of microneedles (MNs) to treat skin wrinkles, developing several products based on solid and dissolvable MNs incorporated with antiwrinkle formulations. However, drug administration via these MNs is limited by the high molecular weight of the drugs. Hollow MNs (HMNs) can deliver a wider array of active agents, but that is a relatively unexplored area in the context of antiwrinkle technology. To address this gap, we discuss the possibility of bioinspired 3D printed HMNs in treating skin wrinkles in this paper. We compare the previous and current anti-wrinkling treatment options, as well as the techniques and challenges involved with its manufacture and commercialization.

Hyaluronic Acid Dissolving Microneedles and Nonablative Fractional Laser for Infraorbital Wrinkles: A Prospective, Randomized, Split-Face Study

Background. Recently, hyaluronic acid dissolving microneedles (HA-DMNs) have been widely used in antiwrinkle research studies. However, the comparison of HA-DMNs with nonablative fractional laser (NAFL), which is regarded as the gold standard in the treatment of facial wrinkles, is still lacking. Objective. The purpose was to compare the therapeutic effects and adverse effects of HA-DMNs and NAFL on infraorbital wrinkles. Methods. A prospective, randomized, split-face trial was performed with HA-DMNs on one side and NAFL on the other. The wrinkle numbers, photo-numeric scores, and VISIA assessment scores were compared at baseline and 2, 4, 8, and 12 weeks post-treatment. Reflectance confocal microscopy (RCM) was used to monitor collagen fibers. Adverse effects and subjects’ satisfaction scores were evaluated using scales. Results. The final analysis included 28 patients. The wrinkle numbers and photo-numeric scores decreased on both the HA-DMNs side and the NAFL side in week-2, 4, 8, and 12. The VISIA scores decreased on the HA-DMNs side in week-8 and on the NAFL side in week-2. There were no significant differences in these indexes between the two sides. The RCM images demonstrated a similar increase in collagen density on the two sides. Burning, erythema, edema, and crust scores were higher on the NAFL side than on the HA-DMNs side. There was no significant difference in the subjects’ satisfaction scores of the two sides. Conclusion. HA-DMNs are effective treatment options for infraorbital rejuvenation. From the change of wrinkle numbers and scores, HA-DMNs provided comparable efficacy as NAFL in an observation period of 12 weeks. Meanwhile, HA-DMNs offered a more favorable adverse effect profile than NAFL therapy. Mild but persistent pain, erythema, and edema during the HA-DMNs therapy are noteworthy and require improvement.

Dissolving microneedles for effective and painless intradermal drug delivery in various skin conditions: A systematic review

Intra- and transdermal administration of substances via percutaneous injection is effective but considered painful, and inconvenient in addition to bringing forth biohazardous waste material. In contrast to injection, topical drug application, which includes ointments, creams and lotions, increases the local drug load. Moreover, it has reduced side effects compared to systemic administration. However, the epidermis poses a barrier to high molecular weight substances, limiting the delivery efficiency. Dissolving microneedles (DMN) are hydrophilic, mostly polymer-based constructs that are capable of skin penetration and were developed to provide painless and direct dermal drug delivery. This systematic review provides a comprehensive overview of the available clinical evidence for the use of DMN to treat various skin conditions. According to the PRISMA statement, a systematic search for articles on the use of DMN for dermatological indications was conducted on three different databases (Pubmed, Embase, and the Cochrane library). Only human clinical trials were considered. Qualitative assessment was done by two separate reviewers using the Cochrane risk of bias (RoB 2) and Chambers' criteria assessment tools. The search yielded 1090 articles. After deduplication and removal of ineligible records, 889 records were screened on title and abstract. Full text screening was done for 18 articles and ultimately 17 articles were included of which 15 were randomized controlled trials and two were case series. The quality assessment showed that the majority of included studies had low to no risk of bias. Clinical data supports that DMN are an excellent, effective, and pain free drug delivery method for multiple dermatological disorders including skin aging, hyperpigmentation, psoriasis, warts, and keloids by supplying a painless and effective vehicle for intradermal/intralesional drug administration. Microneedle technology provides a promising non- to minimally-invasive alternative to percutaneous injection.

Fabrication of High-Resolution Fine Microneedles Derived from Hydrolyzed Hyaluronic Acid Gels in Vacuum Environment Imprinting Using Water Permeable Mold

Hydrolyzed hyaluronic acid high-resolution fine microneedles of 13 µm in diameter and 24 µm in height were fabricated from hydrolyzed hyaluronic acid gels made in mixtures of water using vacuum environment imprint lithography processes with a water permeable mold. The gas traps of water and volatile solvents in the imprint materials cause transfer failure in the conventional water impermeable molds of quartz and metal. However, the water permeable mold allows the use of 67 wt% dilution water with high solubility to increase the fluidity of the hydrolyzed hyaluronic acid during the patterning of high-resolution fine microneedles for cosmetics and pharmaceuticals. This demonstration sets a new paradigm of functional pure gels for high-resolution nano-patterning applications with various cosmetic and pharmaceutical materials containing dilution water using a water permeable mold.

Recent Advances of Hyaluronan for Skin Delivery: From Structure to Fabrication Strategies and Applications

Hyaluronan (HA) plays a fundamental role in maintaining the homeostasis on skin health. Furthermore, the effect of HA in skin inflammatory diseases is worth studying in the next future. HA and its conjugates change the solubility of active pharmaceutical ingredients, improve emulsion properties, prolong stability, reduce immunogenicity, and provide targeting. HA penetrates to deeper layers of the skin via several mechanisms, which depend on the macromolecular structure and composition of the formulation. The cellular and molecular mechanisms involved in epidermal dysfunction and skin aging are not well understood. Nevertheless, HA is known to selectively activate CD44-mediated keratinocyte signaling that regulates its proliferation, migration, and differentiation. The molecular size of HA is critical for molecular mechanisms and interactions with receptors. High molecular weight HA is used in emulsions and low molecular weight is used to form nanostructured lipid carriers, polymeric micelles, bioconjugates, and nanoparticles. In the fabrication of microneedles, HA is combined with other polymers to enhance mechanical properties for piercing the skin. Hence, this review aims to provide an overview of the current state of the art and last reported ways of processing, and applications in skin drug delivery, which will advocate for their broadened use in the future.

An update on biomaterials as microneedle matrixes for biomedical applications

Microneedles (MNs) have been developed for various applications such as drug delivery, cosmetics, diagnosis, and biosensing. To meet the requirements of MNs used in these areas, numerous materials have been used for the fabrication of MNs. However, MNs will be exposed to skin tissues after piercing the stratum corneum barrier. Thus, it is necessary to ensure that the matrix materials of MNs have the characteristics of low toxicity, good biocompatibility, biodegradability, and sufficient mechanical properties for clinical application. In this review, the matrix materials currently used for preparing MNs are summarized and reviewed in terms of these factors. In addition, MN products used on the market and their applications are summarized in the end. This work may provide some basic information to researchers in the selection of MN matrix materials and in developing new materials.

Latest on biomaterial-based therapies for topical treatment of psoriasis

Psoriasis is an autoimmune inflammatory disease which is fundamentally different from dermatitis. Its treatments include topical medications and systemic drugs depending on different stages of the disease. However, these commonly used therapies are falling far short of clinical needs due to various drawbacks. More precise therapeutic strategies with minimized side effects and improved compliance are highly demanded. Recently, the rapid development of biomaterial-based therapies has made it possible and promising to attain topical psoriasis treatment. In this review, we briefly describe the significance and challenges of the topical treatment of psoriasis and emphatically overview the latest progress in novel biomaterial-based topical therapies for psoriasis including microneedles, nanoparticles, nanofibers, and hydrogels. Current clinical trials related to each biomaterial are also summarized and discussed.

Dissolving microneedles: Applications and growing therapeutic potential

Microneedles are a rapidly developing method for the transdermal delivery of therapeutic compounds. All types of microneedles, whether solid, hollow, coated, or dissolving function by penetrating the stratum corneum layer of the skin producing a microchannel through which therapeutic agents may be delivered. To date, coated and hollow microneedles have been the most successful, despite suffering from issues such as poor drug loading capabilities and blocked pores. Dissolving microneedles, on the other hand, have superior drug loading as well as other positive attributes that make it an ideal delivery system, including simple methods of fabrication and disposal, and abundantly available materials. Indeed, dissolvable microneedles can even be fabricated entirely from the therapeutic agent itself thus eliminating the requirement for additional excipients. This focused review presents the recent developments and trends of dissolving microneedles as well as potential future directions. The advantages, and disadvantages of dissolving microneedles as well as fabrication materials and methods are discussed. The potential applications of dissolving microneedles as a drug delivery system in different therapeutic areas in both research literature and clinical trials is highlighted. Applications including the delivery of cosmetics, vaccine delivery, diagnosis and monitoring, cancer, pain and inflammation, diabetes, hair and scalp disorders and inflammatory skin diseases are presented. The current trends observed in the microneedle landscape with particular emphasis on contemporary clinical trials and commercial successes as well as barriers impeding microneedle development and commercialisation are also discussed.

Designing Topical Hyaluronic Acid technology - size does matter…

INTRODUCTION

Hyaluronic acid (HA) plays an important role in cellular and extracellular matrix (ECM) homeostasis. Recent studies demonstrate that low molecular weight (MW) HA has proinflammatory characteristics while high MW HA is considered anti-inflammatory and regenerative. In formulating a topical HA product, the possibility of creating a focused high MW HA technology was posed, combining external surface high MW HA constituents with active agents promoting fibroblast production of high MW in the depths of the dermis.

METHODS

Human dermal fibroblasts and keratinocytes were treated with various agents, and RNA sequencing (RNA-seq) was conducted to identify genes involved in HA synthesis. HA production by fibroblasts was assessed by collecting the culture supernatant, concentrating the protein, and conducting polyacrylamide gel electrophoresis (PAGE). The gel was stained with Stains-All to identify bands relative to known HA products of different MWs. Subsequently, the supernatants were treated with hyaluronidase to confirm the bands corresponded to HA.

RESULTS

The RNA-seq results revealed a variety of agents up-regulated HA-related genes. However, a potent upregulation of HA synthesis gene was observed by hexapeptide-11 in the keratinocytes and a newly identified proprietary octapeptide in the fibroblasts. PAGE demonstrated not only robust production of HA by octapeptide, but significantly, the HA produced was ~2 Mega Daltons in size. Octapeptide was the most potent stimulator among the tested agents.

CONCLUSION

Comprehensive in vitro testing identified a group of active agents that stimulated high MW HA production. This novel approach to HA topical application with exclusively high MW HA production should maximize hydration capacity while encouraging regenerative activity within in the ECM. Multi-center trials are underway.

Recent advances in polymer microneedles for drug transdermal delivery: Design strategies and applications

In recent years, the transdermal drug delivery based on microneedles (MNs) technology has received extensive attention, which offers a safer and painless alternative to hypodermic needle injection. They can pierce the stratum corneum and deliver drugs to the epidermis and dermis-structures of skin, showing prominent properties such as minimally invasive, bypassing first-pass metabolism, and self-administered. A range of materials have been used to fabricate MNs, such as silicon, metal, glass, and polymers. Among them, polymer MNs have gained increasing attention from pharmaceutical and cosmetic companies as one of the promising drug delivery methods. Microneedle products have recently become available on the market, and some of them are under evaluation for efficacy and safety. This paper focuses on current state of polymer MNs in the drug transdermal delivery. The materials and methods for the fabrication of polymer MNs and their drug administration are described. The recent progresses of polymer MNs for treatment of cancer, vaccine delivery, blood glucose regulation, androgenetic alopecia, obesity, tissue healing, myocardial infarction and gout are reviewed. The challenges of MNs technology are summarized and the future development trend of MNs is also prospected. This article is protected by copyright. All rights reserved.

An update on microneedle-based systems for diabetes

Diabetes is one of the most serious chronic diseases today. Patients with diabetes need frequent insulin injections or blood sampling to monitor blood glucose levels. The microneedles are a painless transdermal drug delivery system, which has great advantages in achieving self-management. There have been a lot of researches on microneedles used in diabetes treatment. Microneedle-based treatment of diabetes has also changed from a simple and reliable system to a complex and efficient system. This review introduces microfluidic, glucose response, and other contents based on microneedles, and some challenges in the development of microneedles.

Bioimaging of Dissolvable Microneedle Arrays: Challenges and Opportunities

The emergence of microneedle arrays (MNAs) as a novel, simple, and minimally invasive administration approach largely addresses the challenges of traditional drug delivery. In particular, the dissolvable MNAs act as a promising, multifarious, and well-controlled platform for micro-nanotransport in medical research and cosmetic formulation applications. The effective delivery mostly depends on the behavior of the MNAs penetrated into the body, and accurate assessment is urgently needed. Advanced imaging technologies offer high sensitivity and resolution visualization of cross-scale, multidimensional, and multiparameter information, which can be used as an important aid for the evaluation and development of new MNAs. The combination of MNA technology and imaging can generate considerable new knowledge in a cost-effective manner with regards to the pharmacokinetics and bioavailability of active substances for the treatment of various diseases. In addition, noninvasive imaging techniques allow rapid, receptive assessment of transdermal penetration and drug deposition in various tissues, which could greatly facilitate the translation of experimental MNAs into clinical application. Relying on the recent promising development of bioimaging, this review is aimed at summarizing the current status, challenges, and future perspective on in vivo assessment of MNA drug delivery by various imaging technologies.

The effects of molecular weight of hyaluronic acid on transdermal delivery efficiencies of dissolving microneedles

Hyaluronic acid (HA) is widely adopted to fabricate dissolving microneedles for transdermal drug delivery applications, yet the structure-activity relationship between molecular weight of HA and transdermal delivery efficiency of microneedles (HA-MNs) has not been fully explored, particularly in the transdermal delivery of small molecule drugs. Herein, we report the fabrication of three types of HA-MNs of various molecular weights (10k, 74k and 290k Da), which incorporate rhodamine B as the model drug. We assess the influence of molecular weight of HA on the mechanical properties of HA-MNs and transdermal delivery of rhodamine B in vitro and in vivo. The mechanical strength of all types of HA-MNs exceeds the minimal force requirement for skin penetration, with the highest values of compression force found in 10k-HA-MN. Interestingly, 74k-HA-MN that owns a medium mechanical strength, exhibits the highest efficiency in transdermal delivery of rhodamine B in a porcine skin and a Franz cell transdermal model. Further in vivo fluorescence imaging of HA-MN-treated mice reveals a tunable transdermal delivery of rhodamine B, which is controllable according to the molecular weight of HA. Importantly, 74k-HA-MN treatment demonstrates the highest initial delivering amount and longest retention time of rhodamine B in mice. In addition, histological examinations of puncture sites of the skin tissues confirm the complete recovery of skin and excellent biocompatibility of HA-MNs.

The biological effect of recombinant humanized collagen on damaged skin induced by UV-photoaging: An in vivo study

The application of medical devices to repair skin damage is clinically accepted and natural polymer enjoys an important role in this field, such as collagen or hyaluronic acid, etc. However, the biosafety and efficacy of these implants are still challenged. In this study, a skin damage animal model was prepared by UV-photoaging and recombinant humanized type III collagen (rhCol III) was applied as a bioactive material to implant in vivo to study its biological effect, comparing with saline and uncrosslinked hyaluronic acid (HA). Animal skin conditions were non-invasively and dynamically monitored during the 8 weeks experiment. Histological observation, specific gene expression and other molecular biological methods were applied by the end of the animal experiment. The results indicated that rhCol III could alleviate the skin photoaging caused by UV radiation, including reduce the thickening of epidermis and dermis, increase the secretion of Collagen I (Col I) and Collagen III (Col III) and remodel of extracellular matrix (ECM). Although the cell-material interaction and mechanism need more investigation, the effect of rhCol III on damaged skin was discussed from influence on cells, reconstruction of ECM, and stimulus of small biological molecules based on current results. In conclusion, our findings provided rigorous biosafety information of rhCol III and approved its potential in skin repair and regeneration. Although enormous efforts still need to be made to achieve successful translation from bench to clinic, the recombinant humanized collagen showed superiorities from both safety and efficacy aspects.

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Investigated the biological effect of recombinant humanized collagen type III (rhCol III) in vivo.

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Provided the safety and efficacy evidence for rhCol III in skin damage repair.

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Preliminary mechanism discussion on the biological effect of rhCol III.

Glycosaminoglycans: Sweet as Sugar Targets for Topical Skin Anti-Aging

Glycosaminoglycans (GAGs) are long, linear polysaccharides comprised of repeating disaccharide units with pleiotropic biological functions, with the non-sulfated GAG hyaluronic acid (HA), and sulfated GAGs dermatan sulfate, chondroitin sulfate, heparan sulfate, keratan sulfate, and to a lesser extent heparin all being expressed in skin. Their ability to regulate keratinocyte proliferation and differentiation, inflammatory processes and extracellular matrix composition and quality demonstrates their critical role in regulating skin physiology. Similarly, the water-binding properties of GAGs and structural qualities, particularly for HA, are crucial for maintaining proper skin form and hydration. The biological importance of GAGs, as well as extensive evidence that their properties and functions are altered in both chronological and extrinsic skin aging, makes them highly promising targets to improve cosmetic skin quality. Within the present review, we examine the cutaneous biological activity of GAGs alongside the protein complexes they form called proteoglycans and summarize the age-related changes of these molecules in skin. We also examine current topical interventional approaches to modulate GAGs for improved skin quality such as direct exogenous administration of GAGs, with a particular interest in strategies targeted at potentiating GAG levels in skin through either attenuating GAG degradation or increasing GAG production.

Hyaluronic acid based microneedle array: Recent applications in drug delivery and cosmetology

Microneedles are micron-sized arrays of needles that facilitate drug delivery for local and systemic effects. Hyaluronic acid (HA) is a glycosaminoglycan and is an indigenous component of the connective tissues and dermis. Owing to its versatility and biocompatibility, it has widely been used against various bone, eye, and skin disorders. Therefore, fabricating HA-microneedles is fetching massive global attention. HA based dissolvable microneedles have been immensely explored due to their biodegradable nature. Its degradation residues are very safe. Several attempts have been made to deliver vitamins, proteins, DNAs, and biological macromolecules by HA-microneedles. Here we present the recent advancements in HA-microneedles based application on drug delivery and cosmetology. Its bio-degradation pathways, the receptors on which HA and its derivatives interact, the biological half-lives, and their importance as useful materials for various applications are highlighted. The literature reports identify HA-microneedle as an useful carrier for the delivery of pharmaceuticals.

Translation of Polymeric Microneedles for Treatment of Human Diseases: Recent Trends, Progress, and Challenges

The ongoing search for biodegradable and biocompatible microneedles (MNs) that are strong enough to penetrate skin barriers, easy to prepare, and can be translated for clinical use continues. As such, this review paper is focused upon discussing the key points (e.g., choice polymeric MNs) for the translation of MNs from laboratory to clinical practice. The review reveals that polymers are most appropriately used for dissolvable and swellable MNs due to their wide range of tunable properties and that natural polymers are an ideal material choice as they structurally mimic native cellular environments. It has also been concluded that natural and synthetic polymer combinations are useful as polymers usually lack mechanical strength, stability, or other desired properties for the fabrication and insertion of MNs. This review evaluates fabrication methods and materials choice, disease and health conditions, clinical challenges, and the future of MNs in public healthcare services, focusing on literature from the last decade.

Current advances in the biosynthesis of hyaluronic acid with variable molecular weights

Hyaluronic acid (HA) is a naturally formed acidic mucopolysaccharide, with excellent moisturising properties and used widely in the medicine, cosmetics, and food industries. The industrial production of specific molecular weight HA has become imperative. Different biological activities and physiological functions of HA mainly depend on the degree of polymerisation. This article reviews the research status and development prospects of the green biosynthesis and molecular weight regulation of HA. There is an application-based prerequisite of specific molecular weight of HA that could be regulated either during the fermentation process or via a controlled HA degradation process. This work provides an important theoretical basis for the downstream efficient production of diversified HA, which will further accelerate the research applications of HA and provide a good scientific basis and method reference for the study of the molecular weight regulation of similar biopolymers.

Fabrication, evaluation and applications of dissolving microneedles

In recent years, transdermal preparations have emerged as one of the most promising modes of administration. In particular, dissolving microneedles have attracted extensive attention because of their painlessness, safety, high delivery efficiency and easily operation for patients. This article mainly reviews the preparation methods, the types of matrix polymer materials, the content of dissolving microneedles performance testing, and the applications of dissolving microneedles. It is expected to lay a solid knowledge foundation for the in-depth study of the dissolving microneedles.

Prospective randomized clinical study of a new topical formulation for face wrinkle reduction and dermal regeneration

BACKGROUND

A new topical formulation (TF) based on 3 main lifting components has been developed to reduce superficial facial wrinkles.

OBJECTIVES

Determine the effectiveness of this new TF in reducing superficial face wrinkles and restructuring the dermal matrix.

METHODS

Women, aged 30-65 y.o. with moderate to severe crow's feet wrinkles were included.

EXCLUSION CRITERIA

men; younger than 30 or older than 65 years old; smokers. Patients received 15 IU of botulinum toxin on crow's feet and 2 creams. Fifty patients (Group 1) applied the TP (Product A) and 50 (Group 2) a placebo (Product B). Assessments were made by digital macro-photography's, Antera 3D, and a patient satisfaction questionnaire.

RESULTS

From April to June 2019, 100 women were enrolled in the study and were divided into two homogeneous groups. No major or minor side effects were reported. In group 1, wrinkles, texture, static and dynamic crow's feet wrinkles improved significantly at 3 and 6 months. Patients were very satisfied at 3 months and satisfied at 6 months. In group 2, wrinkles and texture improved significantly at 3 months but did not improve at 6 months. Static and dynamic crow's feet wrinkles improved significantly at 1 and 3 months but did not improve significantly at 6 months.

CONCLUSIONS

Our prospective and randomized study has shown that the new TF is safe and effective in reducing superficial face wrinkles and producing dermal regeneration. It, therefore, prolongs the duration of the botulinum toxin. Further controlled study would be necessary to compare the new TF to neurotoxin treatment, or its action alone.

Biodegradable microneedles fabricated with carbohydrates and proteins: Revolutionary approach for transdermal drug delivery

There has been a surge in the use of transdermal drug delivery systems (TDDS) for the past few years. The market of TDDS is expected to reach USD 7.1 billion by 2023, from USD 5.7 billion in 2018, at a CAGR of 4.5%. Microneedles (MNs) are a novel class of TDDS with advantages of reduced pain, low infection risk, ease of application, controlled release of therapeutic agents, and enhanced bioavailability. Biodegradable MNs fabricated from natural polymers have become the center of attention among formulation scientists because of their recognized biodegradability, biocompatibility, ease of fabrication, and sustainable character. In this review, we summarize the various polysaccharides and polypeptide based biomaterials that are used to fabricate biodegradable MNs. Particular emphasis is given to cellulose and its derivatives, starch, and complex carbohydrate polymers such as alginates, chitosan, chondroitin sulfate, xanthan gum, pullulan, and hyaluronic acid. Additionally, novel protein-based polymers such as zein, collagen, gelatin, fish scale and silk fibroin (polyamino acid) biopolymers application in transdermal drug delivery have also been discussed. The current review will provide a unique perspective to the readers on the developments of biodegradable MNs composed of carbohydrates and protein polymers with their clinical applications and patent status.