Geometrical optimisation of a personalised microneedle eye patch for transdermal delivery of anti-wrinkle small peptide

A Transdermal Prion-Bionics Supermolecule as a RAB3A Antagonist for Enhancing Facial Youthfulness

The mechanism research of skin wrinkles, conducted on volunteers underwent high-intensity desk work and mice subjected to partial sleep deprivation, revealed a significant reduction in dermal thickness associated with the presence of wrinkles. This can be attributed to the activation of facial nerves in a state of hysteria due to an abnormally elevated interaction between SNAP25 and RAB3A proteins involved in the synaptic vesicle cycle (SVC). Facilitated by AI-assisted structural design, a refined peptide called RSIpep is developed to modulate this interaction and normalize SVC. Drawing inspiration from prions, which possess the ability to protect themselves against proteolysis and invade neighboring nerve cells through macropinocytosis, RSIpep is engineered to demonstrate a GSH-responsive reversible self-assembly into a prion-like supermolecule (RSIprion). RSIprion showcases protease resistance, micropinocytosis-dependent cellular internalization, and low adhesion with constituent molecules in the cuticle, thereby endowing it with the transdermic absorption and subsequent biofunction in redressing the frenzied SVC. As a facial mud mask, it effectively reduces periorbital and perinasal wrinkles in the human face. Collectively, RSIprion not only presents a clinical potential as an anti-wrinkle prion-like supermolecule, but also exemplifies a reproducible instance of bionic strategy-guided drug development that bestows transdermal ability upon the pharmaceutical molecule.

Additive manufacturing of microneedles for sensing and drug delivery

INTRODUCTION

Microneedles (MNs) are miniaturized, painless, and minimally invasive platforms that have attracted significant attention over recent decades across multiple fields, such as drug delivery, disease monitoring, disease diagnosis, and cosmetics. Several manufacturing methods have been employed to create MNs; however, these approaches come with drawbacks related to complicated, costly, and time-consuming fabrication processes. In this context, employing additive manufacturing (AM) technology for MN fabrication allows for the quick production of intricate MN prototypes with exceptional precision, providing the flexibility to customize MNs according to the desired shape and dimensions. Furthermore, AM demonstrates significant promise in the fabrication of sophisticated transdermal drug delivery systems and medical devices through the integration of MNs with various technologies.

AREAS COVERED

This review offers an extensive overview of various AM technologies with great potential for the fabrication of MNs. Different types of MNs and the materials utilized in their fabrication are also discussed. Recent applications of 3D-printed MNs in the fields of transdermal drug delivery and biosensing are highlighted.

EXPERT OPINION

This review also mentions the critical obstacles, including drug loading, biocompatibility, and regulatory requirements, which must be resolved to enable the mass-scale adoption of AM methods for MN production, and future trends.

Developing Plant Exosomes as an Advanced Delivery System for Cosmetic Peptide

Peptides are a promising skincare ingredient, but due to their inherent instability and the barrier function of the skin's surface, they often have limited skin absorption and penetration, which can significantly hinder their skincare benefits. To address this, a novel technique called NanoGlow has been introduced for encapsulating peptide-based cosmetic raw materials into engineered nanosized plant-derived exosomes (pExo) to achieve the goal of a healthier and more radiant skin state. In this approach, pExo served as carriers for cosmetic peptides across the intact skin barrier, enhancing their biological effectiveness in skin beauty. The NanoGlow strategy combines chemical activation and physical proencapsulation, boasting a high success rate and straightforward and stable operation, making it suitable for large-scale production. Comprehensive analysis using in vitro cellular absorption and skin penetration models has demonstrated that the nanosized pExo carriers significantly improve peptide penetration into the skin compared to free peptides. Furthermore, in vivo tissue slice studies have shown that pExo carriers efficiently deliver acetyl hexapeptide-8 to the skin's dermis, surpassing the performance of free peptides. Cosmetic skincare effect analysis has also indicated that pExo-loaded cosmetic peptides deliver superior results. Therefore, the NanoGlow technique harnesses the natural size and properties of pExo to maximize the bioavailability of cosmetic peptides, holding great promise for developing advanced peptide delivery systems in both the cosmetic and medical drug industries.

Multi-material 3D printed eutectogel microneedle patches integrated with fast customization and tunable drug delivery

Microneedle patches are emerging multifunctional platforms for transdermal diagnostics and drug delivery. However, it still remains challenging to develop smart microneedles integrated with customization, sensing, detection and drug delivery by 3D printing strategy. Here, we present an innovative but facile strategy to rationally design and fabricate multifunctional eutectogel microneedle (EMN) patches via multi-material 3D printing. Polymerizable deep eutectic solvents (PDES) were selected as printing inks for rapid one-step fabrication of 3D printing functional EMN patches due to fast photopolymerization rate and ultrahigh drug solubility. Moreover, stretchable EMN patches incorporating rigid needles and flexible backing layers were easily realized by changing PDES compositions of multi-material 3D printing. Meanwhile, we developed multifunctional smart multi-material EMN patches capable of performing wireless monitoring of body movements, painless colorimetric glucose detection, and controlled transdermal drug delivery. Thus, such multi-material EMN system could provide an effective platform for the painless diagnosis, detection, and therapy of a variety of diseases.

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.

3D printing of biologics-what has been accomplished to date?

Three-dimensional (3D) printing is a promising approach for the stabilization and delivery of non-living biologics. This versatile tool builds complex structures and customized resolutions, and has significant potential in various industries, especially pharmaceutics and biopharmaceutics. Biologics have become increasingly prevalent in the field of medicine due to their diverse applications and benefits. Stability is the main attribute that must be achieved during the development of biologic formulations. 3D printing could help to stabilize biologics by entrapment, support binding, or crosslinking. Furthermore, gene fragments could be transited into cells during co-printing, when the pores on the membrane are enlarged. This review provides: (i) an introduction to 3D printing technologies and biologics, covering genetic elements, therapeutic proteins, antibodies, and bacteriophages; (ii) an overview of the applications of 3D printing of biologics, including regenerative medicine, gene therapy, and personalized treatments; (iii) information on how 3D printing could help to stabilize and deliver biologics; and (iv) discussion on regulations, challenges, and future directions, including microneedle vaccines, novel 3D printing technologies and artificial-intelligence-facilitated research and product development. Overall, the 3D printing of biologics holds great promise for enhancing human health by providing extended longevity and enhanced quality of life, making it an exciting area in the rapidly evolving field of biomedicine.

Recent advances in delivery of transdermal nutrients: A review

Nutrients provide vital functions in the body for sustained health, which have been shown to be related to the incidence, prevention and treatment of disease. However, limited bioavailability, loss of targeting specificity and the increased hepatic metabolism limit the utilization of nutrients. In this review, we highlight transdermal absorption of nutrients, which represents an opportunity to allow great use of many nutrients with promising human health benefits. Moreover, we describe how the various types of permeation enhancers are increasingly exploited for transdermal nutrient delivery. Chemical penetration enhancers, carrier systems and physical techniques for transdermal nutrient delivery are described, with a focus on combinatorial approaches. Although there are many carrier systems and physical techniques currently in development, with some tools currently in advanced clinical trials, relatively few products have achieved full translation to clinical practice. Challenges and further developments of these tools are discussed here in this review. This review will be useful to researchers interested in transdermal applications of permeation enhancers for the efficient delivery of nutrients, providing a reference for supporting the need to take more account of specific nutritional needs in specific states.

Printable-Microencapsulated Ascorbic Acid for Personalized Topical Delivery

This study presents the successful development of printable-microencapsulated ascorbic acid (AA) for personalized topical delivery using laser printing technology. Rice flour with a 10% AA content was selected as an encapsulation material. Hydrophobic nanosilica was used to create negative electrostatic charges on the microencapsulated surfaces via a high-speed mixture. This process facilitated the microencapsulated AA fabrication using a commercial laser printer and produced a well-patterned design with some minor print defects, such as banding and scattering. The amount of encapsulated AA per area was 0.28 mg/cm2, and the RGB color code was 0,0,0. An emulsion carrier system comprising pentylene glycol (P5G) or diethylene glycol monoethyl ether (DEGEE), Tween 20, oleic acid, and deionized (DI) water at a ratio of 20:30:30:20 was developed to enhance AA transmission into the skin. The Franz diffusion cell technique was used to investigate topical absorption on Strat-M membranes using P5G and DEGEE as enhancers. The steady-state fluxes were 8.40 (±0.64) and 10.04 (±0.58) μg/h/cm2 for P5G and DEGEE, respectively. Cytotoxicity tests conducted on fibroblast cells revealed low cytotoxicity for the encapsulation products and carriers.

Collagen-Based Dissolving Microneedles with Flexible Pedestals: A Transdermal Delivery System for Both Anti-Aging and Skin Diseases

Biocompatible polymer microneedles (MNs) are emerging as a promising platform for transdermal drug delivery, especially for facial treatments. Therefore, an MN patch in this study uses hydrolyzed collagen (HC) contained in skin cells as the main raw material and adopts a two-step cast method to develop a rapidly dissolving microneedle (DMN) to deliver collagen in a simple and minimally invasive way, allowing the release of the encapsulated drug in the skin. By optimizing the formulation and proportion of HC and auxiliary support materials, the mechanical strength required to pierce the skin is obtained, while the soft pedestal allows for flexibility in application. The DMNs can dissolve completely in the skin within 15 min and release within ≈ 8 h, and do not cause toxicity or irritation when being applied. In contrast to the ineffectiveness of oral and external application, and the high risk of dermal injection, drug-loaded DMNs overcome the drawbacks of traditional methods with direct penetration and minimally invasive manner, enabling efficient and safe treatment. The successful preparation and research of HC DMNs have innovative and practical significance in this field, and it is expected to become a simple, effective, and popular transdermal drug delivery platform for cosmetics.

Three Dimensional Printing and Its Applications Focusing on Microneedles for Drug Delivery

Microneedles (MNs) are considered to be a novel smart injection system that causes significantly low skin invasion upon puncturing, due to the micron-sized dimensions that pierce into the skin painlessly. This allows transdermal delivery of numerous therapeutic molecules, such as insulin and vaccines. The fabrication of MNs is carried out through conventional old methods such as molding, as well as through newer and more sophisticated technologies, such as three-dimensional (3D) printing, which is considered to be a superior, more accurate, and more time- and production-efficient method than conventional methods. Three-dimensional printing is becoming an innovative method that is used in education through building intricate models, as well as being employed in the synthesis of fabrics, medical devices, medical implants, and orthoses/prostheses. Moreover, it has revolutionary applications in the pharmaceutical, cosmeceutical, and medical fields. Having the capacity to design patient-tailored devices according to their dimensions, along with specified dosage forms, has allowed 3D printing to stand out in the medical field. The different techniques of 3D printing allow for the production of many types of needles with different materials, such as hollow MNs and solid MNs. This review covers the benefits and drawbacks of 3D printing, methods used in 3D printing, types of 3D-printed MNs, characterization of 3D-printed MNs, general applications of 3D printing, and transdermal delivery using 3D-printed MNs.

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.

Metal-organic frameworks-based microtrapper for real-time monitoring of targeted analyte and mechanism study

Interstitial fluid (ISF) provides important information of clinical value and physiological significance beyond blood tests for obtaining more precise health information and disease theranostics. Generally, current strategies are limited to simple extraction with time-consuming follow-up procedures. Facing challenges in efficient and real-time monitoring of target analytes in transdermal ISF, we develop metal-organic framework (MOF)-functionalized microneedle (MN) patches to achieve efficient antibiotics sampling, coupling direct analysis in real time mass spectrometry (DART-MS). The MOF MN microtrapper is constructed in a double-layered structure with a hard core and a better tissue penetration was accomplished. The MOF-based microtrapper manifests good in-vitro and in-vivo antibiotics tracking capability with a semi-quantitative method established. Moreover, the hydrogen-bond driven interaction is clarified by using molecular dynamics simulations (MDS) and related computational analysis. Good penetration safety is confirmed by histological analysis with promising clinical transnationality. We anticipate MOF MN-based microdevices provide a versatile minimally invasive strategy for transdermal ISF extraction and an extendable platform for a range of target molecules monitoring, including drugs, metabolites, biomarkers, et c, with promising clinical transnationality.

A nanohybrid synthesized by polymeric assembling Au(I)-peptide precursor for anti-wrinkle function

A major sign of aging is wrinkles (dynamic lines and static lines) on the surface of the skin. In spite of Botulinum toxin's favorable therapeutic effect today, there have been several reports of its toxicity and side effects. Therefore, the development of an effective and safe wrinkle-fighting compound is imperative. An antioxidant-wrinkle effect was demonstrated by the peptide that we developed and synthesized, termed Skin Peptide. Aiming at the intrinsic defects of the peptide such as hydrolysis and poor membrane penetration, we developed a general approach to transform the Skin Peptide targeting intracellular protein-protein interaction into a bioavailable peptide-gold spherical nano-hybrid, Skin Pcluster. As expected, the results revealed that Skin Pcluster reduced the content of acetylcholine released by neurons in vitro, and then inhibit neuromuscular signal transmission. Additionally, human experiments demonstrated a significant de-wrinkle effect. Moreover, Skin Pcluster is characterized by a reliable safety profile. Consequently, anti-wrinkle peptides and Skin Pcluster nanohybrids demonstrated innovative anti-wrinkle treatments and have significant potential applications.

A Review of 3D-Printing of Microneedles

Microneedles are micron-sized devices that are used for the transdermal administration of a wide range of active pharmaceutics substances with minimally invasive pain. In the past decade, various additive manufacturing technologies have been used for the fabrication of microneedles; however, they have limitations due to material compatibility and bioavailability and are time-consuming and expensive processes. Additive manufacturing (AM), which is popularly known as 3D-printing, is an innovative technology that builds three-dimensional solid objects (3D). This article provides a comprehensive review of the different 3D-printing technologies that have the potential to revolutionize the manufacturing of microneedles. The application of 3D-printed microneedles in various fields, such as drug delivery, vaccine delivery, cosmetics, therapy, tissue engineering, and diagnostics, are presented. This review also enumerates the challenges that are posed by the 3D-printing technologies, including the manufacturing cost, which limits its viability for large-scale production, the compatibility of the microneedle-based materials with human cells, and concerns around the efficient administration of large dosages of loaded microneedles. Furthermore, the optimization of microneedle design parameters and features for the best printing outcomes is of paramount interest. The Food and Drug Administration (FDA) regulatory guidelines relating to the safe use of microneedle devices are outlined. Finally, this review delineates the implementation of futuristic technologies, such as artificial intelligence algorithms, for 3D-printed microneedles and 4D-printing capabilities.

Design and Evaluation of Complex Polypeptide-Loaded Dissolving Microneedles for Improving Facial Wrinkles in Different Areas

Wrinkles are one of the most intuitive manifestations of skin aging. Complex polypeptide-loaded dissolving microneedles (CP-DMNs) for facial wrinkles in different areas have been developed and evaluated for the first time. In optimizing formulations, we compared the differences in CP-DMNs heights on skin insertion depth and skin repair and healing. Furthermore, systemic safety experiments were carried out to provide a reference for clinical application. On this basis, an 84-day efficacy assessment based on the improvement of facial wrinkles in different areas and a comparison between CP-DMNs vs. placebo was performed on 30 healthy subjects. As a result, DMNs with a height of 300 μm presented sufficient strength to pierce the stratum corneum with minimized skin damage. In addition, CP-DMNs possessed excellent biological safety and skin compatibility for clinical application. Compared with placebo, CP-DMNs exhibited obvious improvements in wrinkles distributed in the corners of eyes, under-eyes, and nasolabial folds. Furthermore, after using CP-DMNs for 84 days, facial wrinkles in five different areas were smoothed. In short, the complex polypeptides showed apparent anti-wrinkle efficacy with the aid of DMNs technology, and CP-DMNs seemed to work better on deeper wrinkles, such as frown lines and nasolabial folds.

3D-printed microneedle arrays for drug delivery

Microneedle arrays provide an efficient tool for transdermal drug delivery in a minimally invasive and painless manner, showing great potential applications in medicine. However, it remains challenging to fabricate the desired microneedle arrays, because of their micron-scale size and fine structure. Novel manufacturing technologies are very wanted for the development of microneedle arrays, which would solidly advance the clinical translation of microneedle arrays. 3D printing technology is a powerful manufacturing technology with superiority in fabricating personalized and complex structures. Currently, 3D printing technology has been employed to fabricate microneedle arrays, which could push more microneedle arrays into clinic and inspire the development of future microneedle arrays. This work reviews the art of 3D printing microneedle arrays, the benefits of fabricating microneedle arrays with 3D printing, and the considerations for clinical translation of 3D-printed microneedle arrays. This work provides an overview of the current 3D-printed microneedle arrays in drug delivery.

A 3D-printed transepidermal microprojection array for human skin microbiome sampling

Skin microbiome sampling is currently performed with tools such as swabs and tape strips to collect microbes from the skin surface. However, these conventional approaches may be unable to detect microbes deeper in the epidermis or in epidermal invaginations. We describe a sampling tool with a depth component, a transepidermal microprojection array (MPA), which captures microbial biomass from both the epidermal surface and deeper skin layers. We leveraged the rapid customizability of 3D printing to enable systematic optimization of MPA for human skin sampling. Evaluation of sampling efficacy on human scalp revealed the optimized MPA was comparable in sensitivity to swab and superior to tape strip, especially for nonstandard skin surfaces. We observed differences in species diversity, with the MPA detecting clinically relevant fungi more often than other approaches. This work delivers a tool in the complex field of skin microbiome sampling to potentially address gaps in our understanding of its role in health and disease.

Investigation and Optimization of Hydrogel Microneedles for Transdermal Delivery of Caffeine

Caffeine is therapeutically effective for treating apnea, cellulite formation, and pain management. It also exhibits neuroprotective and antioxidant activities in different models of Parkinson's disease and Alzheimer's disease. However, caffeine administration in a minimally invasive and sustainable manner through the transdermal route is challenging owing to its hydrophilic nature. Therefore, this study demonstrated a transdermal delivery approach for caffeine by utilizing hydrogel microneedle (MN) as a permeation enhancer. The influence of formulation parameters such as molecular weight (MW) of PMVE/MA (polymethyl vinyl ether/maleic anhydride) copolymer and sodium bicarbonate (NaHCO₃) concentration on the swelling kinetics and mechanical integrity of the hydrogel MNs was investigated. In addition, the effect of different MN application methods and needle densities of hydrogel MN on the skin insertion efficiency and penetration depth was also evaluated. The swelling degree at equilibrium percentage (% S_eq) recorded for hydrogels fabricated with Gantrez S-97 (MW = 1,500,000 Da) was significantly higher than formulation with Gantrez AN-139 (MW = 1,080,000 Da). Increasing the concentration of NaHCO₃ also significantly increased the % S_eq. Moreover, a 100% penetration was recorded for both the applicator and combination of applicator and thumb pressure compared with only 11% for thumb pressure alone. The average diameter of micropores created by the applicator method was 62.94 μm, which was significantly lower than the combination of both applicator and thumb pressure MN application (100.53 μm). Based on histological imaging, the penetration depth of hydrogel MN increased as the MN density per array decreased. The hydrogel MN with the optimized formulation and skin insertion parameters was tested for caffeine delivery in an in vitro Franz diffusion cell setup. Approximately 2.9 mg of caffeine was delivered within 24 h, and the drug release profile was best fitted to the Korsmeyer-Peppas model, displaying Super Case II kinetics. In conclusion, a combination of thumb and impact application methods and reduced needle density improved the skin penetration efficiency of hydrogel MNs. The results also show that hydrogel MNs fabricated from 3% w/w NaHCO₃ and high MW of copolymer exhibit optimum physical and swelling properties for enhanced transdermal delivery.

Skin permeability, a dismissed necessity for anti-wrinkle peptide performance

The skin offers various benefits and potential for peptide delivery if its barrier performance can be reduced temporarily and reversibly. Since peptides possess high molecular weight, hydrophilic nature (in most cases), and ionizable groups in the structure, their skin delivery is highly challenging. Apart from this, they are susceptible to the proteolytic enzymes in the skin. Anti-wrinkle peptides, like other peptides, suffer from insufficient skin permeability, while most of them must penetrate deep in the skin to present their efficacy. Although the cellular studies indicate the effectiveness of such peptides, without the ability to permeate the skin sufficiently, this efficacy is useless. Poor skin permeability of anti-wrinkle peptides has led to ongoing research for finding feasible and noninvasive enhancement methods that would be desirable for consumers of cosmetic products. In this paper, the possibility of skin permeation of anti-wrinkle peptides as well as the chemical, physical, and encapsulation approaches that have been employed to date to increase permeability of these difficult molecules are thoroughly reviewed.

Recent Advances of Microneedles and Their Application in Disease Treatment

For decades, scientists have been doing a lot of research and exploration to find effective long-term analgesic and/or disease-modifying treatments. Microneedles (MNs) are a simple, effective, and painless transdermal drug delivery technology that has emerged in recent years, and exhibits great promise for realizing intelligent drug delivery. With the development of materials science and fabrication technology, the MN transdermal drug delivery technology has been applied and popularized in more and more fields, including chronic illnesses such as arthritis or diabetes, cancer, dermatocosmetology, family planning, and epidemic disease prevention, and has made fruitful achievements. This paper mainly reviews the latest research status of MNs and their fabrication methodology, and summarizes the application of MNs in the treatment of various diseases, as well as the potential to use nanotechnology to develop more intelligent MNs-based drug delivery systems.

Fast Customization of Microneedle Arrays by Static Optical Projection Lithography

Customized microneedle arrays (CMNAs) hold great promise for precise transdermal delivery in a minimally invasive manner. Currently, the fast customization of microneedle arrays remains a great challenge. Here, we show a static optical projection lithography (SOPL) technology for fast 3D printing CMNAs. In this technology, the digital light is statically projected to induce the spatial polymerization of monomer solutions, and therefore microneedle formation can be precisely controlled by the intensity distribution of the projected light. The obtained CMNAs do not have the stair-like surface and layer-by-layer structure that are associated with the common 3D-printing technologies. This method enables fast fabrication of CMNAs with designed shape, size, and distribution in seconds without mechanical motion system. Up-conversion nanoparticles (UCNPs) were delivered into skin by the CMNAs, to form a personalized dot matrix for in vivo information storage. Under the irradiation of near-infrared (NIR) light, the UCNPs in skin displayed a visible dot matrix, presenting information encoded in the structure of CMNAs. This work demonstrates a SOPL technology for rapidly customizing high-quality microneedle arrays and a CMNA-mediated in vivo information storage strategy.

Microneedle-mediated transdermal nanodelivery systems: a review

The greatest limitation in the development of transdermal drug delivery systems is that only a few drugs can permeate the skin due to the barrier function of the stratum corneum. Active and passive methods are generally available for improving the ability of drug transdermal delivery. However, nanoparticles, as a passive approach, exhibit capacity-constrained permeation enhancement. Thus, microneedle-mediated nanoparticles possess enormous potential and broad prospects. Microneedles promote the penetration of macromolecules by creating microchannels on the skin surface. In this review, the prevailing subknowledge on microneedles (mechanism, classification, and applications of microneedles combined with nanoparticles) is discussed to provide a guideline for readers and a basic reference for further in-depth studies of this novel drug delivery system.

3D Printing in Eye Care

Three-dimensional printing enables precise modeling of anatomical structures and has been employed in a broad range of applications across medicine. Its earliest use in eye care included orbital models for training and surgical planning, which have subsequently enabled the design of custom-fit prostheses in oculoplastic surgery. It has evolved to include the production of surgical instruments, diagnostic tools, spectacles, and devices for delivery of drug and radiation therapy. During the COVID-19 pandemic, increased demand for personal protective equipment and supply chain shortages inspired many institutions to 3D-print their own eye protection. Cataract surgery, the most common procedure performed worldwide, may someday make use of custom-printed intraocular lenses. Perhaps its most alluring potential resides in the possibility of printing tissues at a cellular level to address unmet needs in the world of corneal and retinal diseases. Early models toward this end have shown promise for engineering tissues which, while not quite ready for transplantation, can serve as a useful model for in vitro disease and therapeutic research. As more institutions incorporate in-house or outsourced 3D printing for research models and clinical care, ethical and regulatory concerns will become a greater consideration. This report highlights the uses of 3D printing in eye care by subspecialty and clinical modality, with an aim to provide a useful entry point for anyone seeking to engage with the technology in their area of interest.

3D-Printed Products for Topical Skin Applications: From Personalized Dressings to Drug Delivery

3D printing has been widely used for the personalization of therapies and on-demand production of complex pharmaceutical forms. Recently, 3D printing has been explored as a tool for the development of topical dosage forms and wound dressings. Thus, this review aims to present advances related to the use of 3D printing for the development of pharmaceutical and biomedical products for topical skin applications, covering plain dressing and products for the delivery of active ingredients to the skin. Based on the data acquired, the important growth in the number of publications over the last years confirms its interest. The semisolid extrusion technique has been the most reported one, probably because it allows the use of a broad range of polymers, creating the most diverse therapeutic approaches. 3D printing has been an excellent field for customizing dressings, according to individual needs. Studies discussed here imply the use of metals, nanoparticles, drugs, natural compounds and proteins and peptides for the treatment of wound healing, acne, pain relief, and anti-wrinkle, among others. The confluence of 3D printing and topical applications has undeniable advantages, and we would like to encourage the research groups to explore this field to improve the patient's life quality, adherence and treatment efficacy.

The Emerging Role of Ionic Liquid-Based Approaches for Enhanced Skin Permeation of Bioactive Molecules: A Snapshot of the Past Couple of Years

Topical and transdermal delivery systems are of undeniable significance and ubiquity in healthcare, to facilitate the delivery of active pharmaceutical ingredients, respectively, onto or across the skin to enter systemic circulation. From ancient ointments and potions to modern micro/nanotechnological devices, a variety of approaches has been explored over the ages to improve the skin permeation of diverse medicines and cosmetics. Amongst the latest investigational dermal permeation enhancers, ionic liquids have been gaining momentum, and recent years have been prolific in this regard. As such, this review offers an outline of current methods for enhancing percutaneous permeation, highlighting selected reports where ionic liquid-based approaches have been investigated for this purpose. Future perspectives on use of ionic liquids for topical delivery of bioactive peptides are also presented.

Enhanced skin retention and permeation of a novel peptide via structural modification, chemical enhancement, and microneedles

Hyperpigmentation is a common skin condition with serious psychosocial consequences. Decapeptide-12, a novel peptide, has been found to be safer than hydroquinone in reducing melanin content, with efficacy up to more than 50% upon 16 weeks of twice-daily treatment. However, the peptide suffers from limited transcutaneous penetration due to its hydrophilicity and high molecular weight. Therefore, decapeptide-12 was modified by adding a palmitate chain in an attempt to overcome this limitation. Molecular docking results showed that the two peptides exhibited similar biological activity towards tyrosinase. We also tested the effect of chemical penetration enhancers and microneedles to deliver the two peptides into and through skin, using an in vitro human skin permeation method. It was shown that the palm-peptide achieved the best skin retention owing to the increased lipophilicity. In addition, skin permeation of the palm-peptides was enhanced by the chemical skin penetration enhancers, namely, oleic acid and menthol. Skin permeation of the native peptide was enhanced by the microneedle patch but not the chemical skin penetration enhancers. Cutaneous absorption of the palm-peptides was estimated to have achieved its therapeutic concentration within skin. The combinatory approach of using molecular modification, chemical penetration enhancement, and microneedle patch proves to be useful to enhanceskin permeation of the peptides.

3D Printing-A "Touch-Button" Approach to Manufacture Microneedles for Transdermal Drug Delivery

Microneedles (MNs) represent the concept of attractive, minimally invasive puncture devices of micron-sized dimensions that penetrate the skin painlessly and thus facilitate the transdermal administration of a wide range of active substances. MNs have been manufactured by a variety of production technologies, from a range of materials, but most of these manufacturing methods are time-consuming and expensive for screening new designs and making any modifications. Additive manufacturing (AM) has become one of the most revolutionary tools in the pharmaceutical field, with its unique ability to manufacture personalized dosage forms and patient-specific medical devices such as MNs. This review aims to summarize various 3D printing technologies that can produce MNs from digital models in a single step, including a survey on their benefits and drawbacks. In addition, this paper highlights current research in the field of 3D printed MN-assisted transdermal drug delivery systems and analyzes parameters affecting the mechanical properties of 3D printed MNs. The current regulatory framework associated with 3D printed MNs as well as different methods for the analysis and evaluation of 3D printed MN properties are outlined.

Diving into 3D (bio)printing: A revolutionary tool to customize the production of drug and cell-based systems for skin delivery

The incorporation of 3D printing technologies in the pharmaceutical industry can revolutionize its R&D, by providing a simple and rapid method to produce tailored one-off batches, each with customized dosages, different compounds, shapes, sizes, and adjusted release rates. Particularly, this type of technology can be advantageous for the development of topical and transdermal drug delivery systems, including patches and microneedles. The use of both systems as drug carriers offers advantages over the oral administration, but the possibility of skin irritation and sensitization, and the high production costs, may hinder the expansion of this market. In this context, 3D printing, a high-resolution technique, allows the design of high quality, personalized, complex and sophisticated structures, thus reducing the production costs and improving the patient compliance. This review covers the 3D printing concept and discusses the relevance of this technology to the pharmaceutical industry, with a special focus on the development of topical and transdermal products - patches and microneedles. The potential of 3D bioprinting for skin applications is also presented, highlighting the development of patch-like skin constructs for wound and burn treatment, and skin equivalents for in vitro research and drug development. Several recent studies were selected to support the relevance of the subjects addressed herein. Additionally, the limitations of these printing technologies are discussed, including regulatory, quality and safety issues.

Microneedle based adipose derived stem cells-derived extracellular vesicles therapy ameliorates UV-induced photoaging in SKH-1 mice

Extracellular vesicles from adipose derived stem cells (ADSCs-EVs) have shown immunomodulation and anti-photoaging effects; however, the skin barrier prevents their absorption via skin. Meanwhile, microneedle (MN) is a widely used and minimally invasive tool for dermal delivery of drugs, it also has neocollagenesis effect by creating tiny injuries and initiating wound healing process. To investigate the effect of MN combined with ADSCs-EVs on skin aging, photoaging in SKH-1 mice was induced by chronic exposure to ultraviolet radiation. Then the mice were treated following a split-dorsal scheme, in which one side had MN alone or MN + EVs treatment and the other side was left untreated. For the side treated with MN alone or MN + EVs, the epidermal thickness was decreased and the skin barrier function was enhanced compared with the untreated side. However, MN + EVs group showed the least wrinkles, the highest collagen density and the most organized collagen fibers among the three groups. The level of CD11b + cell infiltration was lower in MN + EVs group than that in the MN group at 3 day after the treatment. These results indicated that MN treatment alone could improve epidermal structure and function of photoaging skin, and a combination with ADSCs-EVs would accelerate the restoration of inflammation caused by MN and improve the content of collagen. In all, this study indicated that a combination of MN and topical applied ADSCs-EVs was a feasible and safe strategy to ameliorate photoaging, providing a new avenue for safe administration of EVs.

3D printing as a transformative tool for microneedle systems: Recent advances, manufacturing considerations and market potential

The present review aims at identifying the key progress points that have been made on the use of 3D printing to manufacture microneedles in the past 3 years. The advances in the field of photopolymerization and extrusion-based 3D printing are outlined. The study revealed that the printing resolution and the material properties are the two critical parameters that have the most influential effect on the outcome of every microneedle printing endeavour. Finally, the authors attempt to estimate the impact of 3D printing on the transdermal drug delivery market.

Recent advances in mechanical force-assisted transdermal delivery of macromolecular drugs

The transdermal delivery of macromolecular drugs has become one of the focused topics in pharmaceutical research since it enables highly specific and effective delivery, while avoiding the pain and needle phobia associated with injection, or incidences like drug degradation and low bioavailability of oral administration. However, the passive absorption of macromolecular drugs via skin is highly restricted by the stratum corneum owing to high molecular weight. Therefore, various strategies have been extensively developed and conducted to facilitate the transdermal delivery of macromolecular drugs, among which, mechanical force-assisted techniques occupy dominant positions. Such techniques include ultrasound, needle-free jet injection, temporary pressure and microneedles. In this review, we focus on recent transdermal enhancing strategies utilizing mechanical force, and summarize their mechanisms, advantages, limitations and clinical applications respectively.

Micro/nanodevices for assessment and treatment in stomatology and ophthalmology

Micro/nanodevices have been widely applied for the real-time monitoring of intracellular activities and the delivery of exogenous substances in the past few years. This review focuses on miniaturized micro/nanodevices for assessment and treatment in stomatology and ophthalmology. We first summarize the recent progress in this field by examining the available materials and fabrication techniques, device design principles, mechanisms, and biosafety aspects of micro/nanodevices. Following a discussion of biochemical sensing technology from the cellular level to the tissue level for disease assessment, we then summarize the use of microneedles and other micro/nanodevices in the treatment of oral and ocular diseases and conditions, including oral cancer, eye wrinkles, keratitis, and infections. Along with the identified key challenges, this review concludes with future directions as a small fraction of vast opportunities, calling for joint efforts between clinicians and engineers with diverse backgrounds to help facilitate the rapid development of this burgeoning field in stomatology and ophthalmology.

Peptides as Active Ingredients: A Challenge for Cosmeceutical Industry

Cosmeceutical field, which merges cosmetics and pharmaceuticals, is nowadays a highly investigated research area, because a scientific demonstration of the claimed bioactivity of new cosmeceutical ingredients is increasingly requested. In fact, an aspect differentiating traditional cosmetics from cosmeceuticals is the identification and characterization of the active ingredients and demonstrating its efficacy in the claimed activity. An interesting group of bioactive cosmeceutical ingredients are peptides, which due to their particular properties, meets most of the requirements presented by the cosmeceutical industry when composing new formulas. In this context, beside bioactivity, two additional aspects have been recently considered, when dealing with peptides as cosmeceutical ingredients: bioavailability and stability. We describe herein novel methods applied in order to enhance peptides skin-penetration and stability, reviewing both scientific articles and patents, issued in the cosmeceutical arena.

Cosmeceutical Peptides in the Framework of Sustainable Wellness Economy

Among the many aspects that contribute to the wellness of each individual, healthy and younger-looking skin play a relevant role, as clearly shown by the important growth of the skin-care products market observed in recent years. In this scenario, the field of cosmeceuticals appears particularly promising, being based on cosmetic products containing active ingredients. Among these, several peptides were proposed for cosmeceutical applications, thanks to their specific interaction with biological targets. In this mini-review, we report some of the most investigated and used peptides for cosmetic formulations, taking into account that cosmeceutical peptides are basically divided into three main categories (i.e., neurotransmitter inhibitors, carriers, and signal peptides). Special attention was payed to the scientific studies supporting the claimed biological activity of these peptides, as a fundamental aspect that should underpin the growth of this field in the framework of a sustainable wellness economy.

Microneedles: Characteristics, Materials, Production Methods and Commercial Development

Although transdermal drug delivery systems (DDS) offer numerous benefits for patients, including the avoidance of both gastric irritation and first-pass metabolism effect, as well as improved patient compliance, only a limited number of active pharmaceutical ingredients (APIs) can be delivered accordingly. Microneedles (MNs) represent one of the most promising concepts for effective transdermal drug delivery that penetrate the protective skin barrier in a minimally invasive and painless manner. The first MNs were produced in the 90s, and since then, this field has been continually evolving. Therefore, different manufacturing methods, not only for MNs but also MN molds, are introduced, which allows for the cost-effective production of MNs for drug and vaccine delivery and even diagnostic/monitoring purposes. The focus of this review is to give a brief overview of MN characteristics, material composition, as well as the production and commercial development of MN-based systems.