Skin Barriers in Dermal Drug Delivery: Which Barriers Have to Be Overcome and How Can We Measure Them?

Non-Invasive Depth Profiling of Base Cosmetic Formulations in the Skin Using Handheld Confocal Raman Spectroscopy

Ceramide-based and aqueous-based moisturizers have distinct absorption and retention characteristics in skin. Conventional methods like Transepidermal Water Loss (TEWL) and Corneometry are limited by environmental factors, and no current in vivo method measures ceramide content in skin. This research explores the use of a handheld Confocal Raman Spectroscopy (CRS) system to non-invasively analyze the absorption kinetics of these moisturizers. Measurements were taken on 40 subjects, including healthy individuals (n = 20) and those with atopic dermatitis (n = 20). Results showed that ceramide-based creams retained ceramide in the stratum corneum for longer periods, particularly 24 h post-application, compared to aqueous-based creams. Validation against Liquid Chromatography-Mass Spectrometry (LCMS) for ceramide NP in four healthy subjects showed a strong correlation (r = 0.96). These findings suggest that handheld CRS can improve the evaluation of skincare formulations, advancing the development of personalized skincare solutions.

Advances of dual-organ and multi-organ systems for gut, lung, skin and liver models in absorption and metabolism studies

Drug development is a costly and timely process with high risks of failure during clinical trials. Although in vitro tissue models have significantly advanced over the years, thus fostering a transition from animal-derived models towards human-derived models, failure rates still remain high. Current cell-based assays are still not able to provide an accurate prediction of the clinical success or failure of a drug candidate. To overcome the limitations of current methods, a variety of microfluidic systems have been developed as powerful tools that are capable of mimicking (micro)physiological conditions more closely by integrating physiological fluid flow conditions, mechanobiological cues and concentration gradients, to name only a few. One major advantage of these biochip-based tissue cultures, however, is their ability to seamlessly connect different organ models, thereby allowing the study of organ-crosstalk and metabolic byproduct effects. This is especially important when assessing absorption, distribution, metabolism, and excretion (ADME) processes of drug candidates, where an interplay between various organs is a prerequisite. In the current review, a number of in vitro models as well as microfluidic dual- and multi-organ systems are summarized with a focus on absorption (skin, lung, gut) and metabolism (liver). Additionally, the advantage of multi-organ chips in identifying a drug's on and off-target toxicity is discussed. Finally, the potential high-throughput implementation and modular chip design of multi-organ-on-a-chip systems within the pharmaceutical industry is highlighted, outlining the necessity of reducing handling complexity.

Vitamin D: Beyond Traditional Roles-Insights into Its Biochemical Pathways and Physiological Impacts

Background: It is true that vitamin D did not earn its title as the "sunshine vitamin" for nothing. In recent years, however, there has been a shift in the perception surrounding vitamin D to a type of hormone that boasts countless bioactivities and health advantages. Historically, vitamin D has been known to take care of skeletal integrity and the calcium-phosphorus balance in the body, but new scientific research displays a much larger spectrum of actions handled by this vitamin. Materials and Methods: A systematic literature search was performed using the following electronic databases: PubMed, Scopus, Web of Science, Embase, and Cochrane Library. Results: Many emerging new ideas, especially concerning alternative hormonal pathways and vitamin D analogs, are uniformly challenging the classic "one hormone-one receptor" hypothesis. To add more context to this, the vitamin D receptor (VDR) was previously assumed to be the only means through which the biologically active steroid 1,25-dihydroxyvitamin D3 could impact the body. Two other molecules apart from the active hormonal form of 1,25(OH)2D3 have gained interest in recent years, and these have reinvigorated research on D3 metabolism. These metabolites can interact with several other nuclear receptors (like related orphan receptor alpha-RORα, related orphan receptor gamma-RORγ, and aryl hydrocarbon receptor-AhR) and trigger various biological responses. Conclusions: This paper thus makes a case for placing vitamin D at the forefront of new holistic and dermatological health research by investigating the potential synergies between the canonical and noncanonical vitamin D pathways. This means that there are now plentiful new opportunities for manipulating and understanding the full spectrum of vitamin D actions, far beyond those related to minerals.

Current issues in optical monitoring of drug delivery via hair follicles

Drug delivery via hair follicles has attracted much research attention due to its potential to serve for both local and systemic therapeutic purposes. Recent studies on topical application of various particulate formulations have demonstrated a great role of this delivery route for targeting numerous cell populations located in skin and transporting the encapsulated drug molecules to the bloodstream. Despite a great promise of follicle-targeting carriers, their clinical implementation is very rare, mostly because of their poorer characterization compared to conventional topical dosage forms, such as ointments and creams, which have a history spanning over a century. Gathering as complete information as possible on the intrafollicular penetration depth, storage, degradation/metabolization profiles of such carriers and the release kinetics of drugs they contain, as well as their impact on skin health would significantly contribute to understanding the pros and cons of each carrier type and facilitate the selection of the most suitable candidates for clinical trials. Optical imaging and spectroscopic techniques are extensively applied to study dermal penetration of drugs. Current paper provides the state-of-the-art overview of techniques, which are used in optical monitoring of follicular drug delivery, with a special focus on non-invasive in vivo methods. It discusses key features, advantages and limitations of their use, as well as provide expert perspectives on future directions in this field.

Liposomal Nanocarriers to Enhance Skin Delivery of Chemotherapeutics in Cancer Therapy

Cancer chemotherapeutics administered to cancer patients via traditional oral or parenteral routes often encounter poor bioavailability and severe systemic side effects. Skin delivery is a promising alternative route with reduced side effects and improved therapeutic efficacy and has gained significant attention in recent years. With conventional or deformable liposomal nanocarriers as a skin permeation strategy, cancer chemotherapeutics can be delivered via skin route, offering an option for more efficient therapy. This review summarizes the recent advances in liposome nanocarrier efficacy to enhance the skin delivery of chemotherapeutics with a wide range of physicochemical properties (log Poct from -0.89 to 5.93, MW from 130 to 1415) in targeting local skin cancer, breast cancer, and tumor metastasis and delivering the drug to systemic circulation to treat distal cancers. The potential mechanisms of skin permeation enhancement by different type of liposomes are also discussed in this review.

Fabrication and Evaluation of Dissolving Hyaluronic Acid Microneedle Patches for Minimally Invasive Transdermal Drug Delivery by Nanoimprinting

Transdermal drug delivery minimizes pain and provides a controlled, stable release of drugs, but its effectiveness is limited by the skin's natural barriers. Microneedles overcome this problem, enabling minimally invasive drug delivery. Microneedle patches (MNPs) with 80 µm-tall needles composed of hyaluronic acid (HA) were developed and evaluated for their formability, structural integrity, dissolution rate, skin penetration ability, and drug transmission capacity. The influence of the molecular weight of HA on these properties was also investigated. MNPs made from low-molecular-weight HA (30 kDa-50 kDa) demonstrated 12.5 times superior drug permeability in ex vivo human skin compared to needleless patches (NLPs). Furthermore, in the same test, low-molecular-weight HA MNPs had 1.7 times higher drug permeability than high-molecular-weight HA MNPs, suggesting superior transdermal administration. The molecular weight of HA significantly influenced its solubility and permeability, highlighting the potential effectiveness of MNPs as drug delivery systems. Puncture tests demonstrated a penetration depth of 50-60 µm, indicating minimal nerve irritation in the dermis and effective drug delivery to the superficial dermal layer. These results present a manufacturing technique for MNPs incorporating model drug compounds and highlight their potential as a novel and minimally invasive drug delivery method for the biomedical applications of soft gels.

The Potential Application of Nanocarriers in Delivering Topical Antioxidants

The imbalance in the production of reactive oxygen species (ROS) with endogenous antioxidant capacity leads to oxidative stress, which drives many disorders, especially in the skin. In such conditions, supplementing exogenous antioxidants may help the body prevent the negative effect of ROS. However, the skin, as the outermost barrier of the body, provides a perfect barricade, making the antioxidant delivery complicated. Several strategies have been developed to enhance the penetration of antioxidants through the skin, one of which is nanotechnology. This review focuses on utilizing several nanocarrier systems, including nanoemulsions, liposomes, solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), and polymeric nanoparticles, for transporting antioxidants into the skin. We also reveal ROS formation in the skin and the role of antioxidant therapy, as well as the natural sources of antioxidants. Furthermore, we discuss the clinical application of topical antioxidant therapy concomitantly with the current status of using nanotechnology to deliver topical antioxidants. This review will accelerate the advancement of topical antioxidant therapy.

Multi-Layered Microneedles Loaded with Microspheres

Delivery of therapies into skin is attractive for medical indications including vaccination and treatment of dermatoses but is highly constrained by the stratum corneum barrier. Microneedle (MN) patches have emerged as a promising technology to enable non-invasive, intuitive, and low-cost skin delivery. When combined with biodegradable polymer formulations, MN patches can further enable controlled-release drug delivery without injection. Herein, we sought to expand on the capability of MN patches to deliver therapies into skin by providing improved spatiotemporal control. Polylactic-co-glycolic acid (PLGA) microspheres were used to encapsulate model dye and then loaded into MN patches through a layer-by-layer fabrication method that created multiple layers of different composition within each MN. MN patches were loaded with up to 5 μg/MN of PLGA microspheres. Mechanical testing demonstrated that mechanical strength of MNs decreased with increasing number of microsphere layers. Microsphere-loaded MN patches inserted into porcine skin ex vivo and murine skin in vivo fully dissolved within 15 min, administering drug-loaded microspheres for controlled release lasting over 45 days. These data support the feasibility of multi-layered, microsphere-loaded MN patches designed for spatially targeted and sustained delivery of therapies into skin.

An overview of phospholipid enriched-edge activator-based vesicle nanocarriers: new paradigms to treat skin cancer

Skin cancer poses a significant global health concern necessitating innovative treatment approaches. This review explores the potential of vesicle nanoformulation incorporating EA (edge activators) to overcome barriers in skin cancer management. The skin's inherent protective mechanisms, specifically the outermost layer called the stratum corneum and the network of blood arteries, impede the permeation of drugs. Phospholipid-enriched EA based nanoformulation offer a promising solution by enhancing drug penetration through skin barriers. EAs like Span 80, Span 20, Tween 20, and sodium cholate etc., enhance vesicles deformability, influencing drug permeation. This review discusses topical application of drugs treat skin cancer, highlighting challenges connected with the conventional liposome and the significance of using EA-based nanoformulation in overcoming these challenges. Furthermore, it provides insights into various EA characteristics, critical insights, clinical trials, and patents. The review also offers a concise overview of composition, preparation techniques, and the application of EA-based nanoformulation such as transfersomes, transliposomes, transethosomes, and transniosomes for delivering drugs to treat skin cancer. Overall, this review intends to accelerate the development of formulations that incorporate EA, which would further improve topical drug delivery and enhance therapeutic outcomes in skin cancer treatment.

Effect of Alcohols on the Skin Permeation of Various Drugs

In this study we have focused on three types of alcohols: ethanol (EtOH), 2-propanol (IPA), and 1-propanol (NPA), and examined the skin permeability of drugs with different physicochemical properties: ketoprofen (KPF; hydrophobic), cimetidine (CMT; slightly hydrophobic), and caffeine (CF; hydrophilic). The results revealed EtOH particularly enhanced the skin permeation of CF, while IPA enhanced skin permeation regardless of the type of drug. In contrast, NPA significantly increased the skin permeability of KPF and CMT, but had little effect on CF. The differing effects of the alcohols on skin permeation appear to be linked to the physicochemical properties of the drugs. KPF is more hydrophobic than the other drugs, suggesting that it uses the intercellular pathway in the stratum corneum for permeation. CMT has intermediate properties between hydrophilic and hydrophobic, resulting in low skin permeability and ineffective utilization of both the transepidermal and transappendageal pathways. CF mainly utilized the transappendageal pathways for skin permeation because of its smaller molecular weight and more hydrophilic as compared with the other drugs. These results suggest that the effect of different alcohols on enhancing drug skin permeation is not uniform and that the optimal alcohol for enhancing permeability may vary depending on the drug. Therefore, the selection of appropriate additives based on the physicochemical properties of the drug, such as hydrophilicity, hydrophobicity, and molecular weight, is crucial for developing effective transdermal formulation.

Luliconazole-loaded nanostructured lipid carrier: formulation, characterization, and in vitro antifungal evaluation against a panel of resistant fungal strains

Luliconazole (LCZ) is a topical imidazole antifungal agent with broad-spectrum activity. However, LCZ encounters challenges such as low aqueous solubility, skin retention, and penetration, which reduce its dermal bioavailability and hinder its efficacy in drug delivery. The aim of the present study was to formulate, characterize, and evaluate the in vitro antifungal efficacy of luliconazole-loaded nanostructured lipid carriers (LCZ-NLCs) against a panel of resistant fungal strains. The LCZ-NLCs were synthesized using a modified emulsification-solvent evaporation technique. Characterization involved assessing parameters such as poly-dispersity index (PDI), zeta potential, encapsulation efficiency (EE %), Field Emission Scanning Electron Microscopy (FESEM), Differential Scanning Calorimetry (DSC) analysis, and Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR). Furthermore, in vitro drug release experiments, analysis of release kinetics, cytotoxicity assessments, and in vitro antifungal susceptibility tests were performed as part of the study. The findings indicated that LCZ-NLCs displayed nanoscale dimensions, uniform dispersion, and a favorable zeta potential. The encapsulation efficiency of LCZ in NLCs was approximately 90%. FESEM analysis revealed spherical nanoparticles with consistent shape. ATR-FTIR analysis indicated no chemical interaction between LCZ and excipients. In vitro drug release experiments demonstrated that LCZ-NLCs notably improved the drug's dissolution rate. The stability testing confirmed consistent colloidal nanometer ranges in the LCZ-NLCs samples. Additionally, cytotoxicity tests revealed no toxicity within the tested concentration. Moreover, in vitro antifungal susceptibility tests demonstrated potent antifungal activity of LCZ-NLCs against the tested resistant fungal isolates. The study findings suggest that the LCZ-NLCs formulation developed in this research could be a promising topical treatment for superficial fungal infections, especially in cases of resistant infections. However, the study needs further ex vivo and in vivo tests to ensure safety and efficacy.

Systematic characterization of the barrier function of diverse ex vivo models of damaged human skin

Background

The skin barrier plays a crucial role in protecting our body against external agents. Disruption of this barrier's function leads to increased susceptibility to infections and dermatological diseases. Damaged skin can be due to the use of detergents, sunburn or excessive scratching. In the context of the COVID-19 pandemic the recommended hygiene measures to prevent the spread of SARS-CoV-2, such as wearing masks, frequent handwashing, and the use of sanitizers, can also potentially alter the skin barrier.

Objectives

The purpose of the study was to characterize the barrier function of ex vivo models of damaged human skin.

Methods

Skin barrier damage was induced through different chemical and mechanical treatments, representative of the potential factors damaging human skin. The skin barrier function was evaluated in terms of permeability, dermal absorption capacity, stratum corneum thickness and gene expression of barrier markers. As inflammation is linked to skin barrier integrity, inflammatory markers were also analyzed.

Results and discussion

The different treatments applied to ex vivo skin models allow the simulation of diverse degrees of skin damage, making these models valuable for assessing the efficacy of topical products targeted at skin repair and for studying the effects of compromised skin barrier on viral penetration.

Synergistic Strategies of Biomolecular Transport Technologies in Transdermal Healthcare Systems

Transdermal healthcare systems have gained significant attention for their painless and convenient drug administration, as well as their ability to detect biomarkers promptly. However, the skin barrier limits the candidates of biomolecules that can be transported, and reliance on simple diffusion poses a bottleneck for personalized diagnosis and treatment. Consequently, recent advancements in transdermal transport technologies have evolved toward active methods based on external energy sources. Multiple combinations of these technologies have also shown promise for increasing therapeutic effectiveness and diagnostic accuracy as delivery efficiency is maximized. Furthermore, wearable healthcare platforms are being developed in diverse aspects for patient convenience, safety, and on-demand treatment. Herein, a comprehensive overview of active transdermal delivery technologies is provided, highlighting the combination-based diagnostics, therapeutics, and theragnostics, along with the latest trends in platform advancements. This offers insights into the potential applications of next-generation wearable transdermal medical devices for personalized autonomous healthcare.

Topical application of anti-inflammatory agents on burn wounds and their effect on healing

Advancements in the treatment of burns have considerably improved overall survival rates, but they have also highlighted several long-term sequelae related to the injury. Hypertrophic scars can impair function, reduce quality of life, and require multiple procedures as well as physical therapy. The purpose of this study was to investigate the effects of topical application of anti-inflammatory drugs in the treatment of burns. Up to 15 deep-partial thickness burns were created on the dorsum of four anesthetized swine. Subsequently, the burn wounds were randomized to receive amiloride, celecoxib, dexamethasone or minocycline mixed in a hydrogel. Silver sulfadiazine cream and blank hydrogel acted as controls. The animals were followed for 90 days and the wounds were assessed on days 3, 7, 14, 28 and 90 post-burn. Assessments were performed using photographs (macroscopic healing, contraction), laser-speckle imaging (blood perfusion), 3D camera (scarring, pigmentation), and histology (inflammation, burn depth, epidermal maturation). Inflammation was present in all burn wound histology specimens and peaked on day 7 in all groups. Regardless of the treatment the burns progressed and were deeper on day 7 in comparison to day 3. The burns were 50 - 80 % healed by day 14, but no significant differences were observed. No differences in epidermal thickness, rete ridges, contraction, hypopigmentation, or scar elevation were seen on day 90. Topical anti-inflammatories did not significantly decrease inflammation or mitigate burn wound progression in deep partial thickness burns in pigs. Also, no significant differences in wound healing or quality of healing were observed.

Transdermal Delivery of Tofacitinib Citrate via Mannose-Decorated Transferosomes Loaded with Tofacitinib Citrate in Arthritic Joints

Transdermal drug delivery systems are a promising option for the treatment of rheumatoid arthritis (RA) because they can lower systemic adverse effects of immunosuppressants. Janus kinase (JAK) inhibitors were found to be effective for the treatment of RA by inhibiting the JAK-STAT pathway and preventing autoimmune joint destruction. The aim of this study is to deliver tofacitinib (a JAK 1 and 3 inhibitor) through mannose-decorated transferosomes (MDTs) directly to inflamed joints. Transferosomes are composed of phospholipids, Cremophor A25, PEG400, Labrafac lipophile, and oleic acid to enhance the permeation of tofacitinib and control nanovesicle size (∼70-200 nm). Permeation through rat skin was evaluated, where the skin permeation of MDTs (Q24: 38.8 ± 9.82 μg/cm2) and flux (0.5311 ± 0.072 μg/cm2/h) were significantly greater than those of the uncoated transferosomes (Q24 of T1: 1.522 ± 0.329 μg/cm2, Q24 of T2: 3.5002 ± 0.998 μg/cm2, and Q24 of T3: 18.226 ± 5.25 μg/cm2). In addition, MDTs seem to permeate the skin intact, as shown by the transmission electron microscopy (TEM) images of the recipient buffer removed from the Franz diffusion cell. A histopathology assay was performed during the in vivo evaluation of MDTs in an arthritic rat model, in which, significantly less inflammation was observed when MDTs were applied directly to the joint compared to when applied to the dorsal skin and untreated arthritic joints. Furthermore, significantly lower tumor necrosis factor-α (TNFα), IL-6, and IL-1β levels (P < 0.05) were detected by enzyme-linked immunosorbent assay (ELISA) in homogenates of the joints treated with MDTs than in untreated arthritic joints. In conclusion, this study proposed effective MDTs that could deliver tofacitinib directly to inflamed joints possibly by targeting the macrophages circulating in the proximity of the site of inflammation.

Topical Nanoliposomal Collagen Delivery for Targeted Fibril Formation by Electrical Stimulation

Collagen is a complex, large protein molecule that presents a challenge in delivering it to the skin due to its size and intricate structure. However, conventional collagen delivery methods are either invasive or may affect the protein's structural integrity. This study introduces a novel approach involving the encapsulation of collagen monomers within zwitterionic nanoliposomes, termed Lip-Cols, and the controlled formation of collagen fibrils through electric fields (EF) stimulation. The results reveal the self-assembly process of Lip-Cols through electroporation and a pH gradient change uniquely triggered by EF, leading to the alignment and aggregation of Lip-Cols on the electrode interface. Notably, Lip-Cols exhibit the capability to direct the orientation of collagen fibrils within human dermal fibroblasts. In conjunction with EF, Lip-Cols can deliver collagen into the dermal layer and increase the collagen amount in the skin. The findings provide novel insights into the directed formation of collagen fibrils via electrical stimulation and the potential of Lip-Cols as a non-invasive drug delivery system for anti-aging applications.

An Overview of Film-Forming Emulsions for Dermal and Transdermal Drug Delivery

Drug delivery through the skin is a widely used therapeutic method for the treatment of local dermatologic conditions. Dermal and transdermal methods of drug delivery offer numerous advantages, but some of the most important aspects of drug absorption through the skin need to be considered. Film-forming systems (FFS) represent a new mode of sustained drug delivery that can be used to replace traditional topical formulations such as creams, ointments, pastes, or patches. They are available in various forms, including solutions, gels, and emulsions, and can be categorised as film-forming gels and film-forming emulsions. Film-forming emulsions (FFE) are designed as oil-in-water (O/W) emulsions that form a film with oil droplets encapsulated in a dry polymer matrix, thus maintaining their dispersed nature. They offer several advantages, including improved solubility, bioavailability and chemical stability of lipophilic drugs. In addition, they could improve the penetration and diffusion of drugs through the skin and enhance their absorption at the target site due to the nature of the components used in the formulation. The aim of this review is to provide an up-to-date compilation of the technologies used in film-forming emulsions to support their development and availability on the market as well as the development of new pharmaceutical forms.

Iontophoresis and electroporation-assisted microneedles: advancements and therapeutic potentials in transdermal drug delivery

Transdermal drug delivery (TDD) using electrically assisted microneedle (MN) systems has emerged as a promising alternative to traditional drug administration routes. This review explores recent advancements in this technology across various therapeutic applications. Integrating iontophoresis (IP) and electroporation (EP) with MN technology has shown significant potential in improving treatment outcomes for various conditions. Studies demonstrate their effectiveness in enhancing vaccine and DNA delivery, improving diabetes management, and increasing efficacy in dermatological applications. The technology has also exhibited promise in delivering nonsteroidal anti-inflammatory drugs (NSAIDs), treating multiple sclerosis, and advancing obesity and cancer therapy. These systems offer improved drug permeation, targeted delivery, and enhanced therapeutic effects. While challenges remain, including safety concerns and technological limitations, ongoing research focuses on optimizing these systems for broader clinical applications. The future of electrically assisted MN technologies in TDD appears promising, with potential advancements in personalized medicine, smart monitoring systems, and expanded therapeutic applications.

Senescence Rejuvenation through Reduction in Mitochondrial Reactive Oxygen Species Generation by Polygonum cuspidatum Extract: In Vitro Evidence

Oxidative stress caused by reactive oxygen species (ROS) is one of the major causes of senescence. Strategies to reduce ROS are known to be important factors in reversing senescence, but effective strategies have not been found. In this study, we screened substances commonly used as cosmetic additives to find substances with antioxidant effects. Polygonum cuspidatum (P. cuspidatum) extract significantly reduced ROS levels in senescent cells. A novel mechanism was discovered in which P. cuspidatum extract reduced ROS, a byproduct of inefficient oxidative phosphorylation (OXPHOS), by increasing OXPHOS efficiency. The reduction in ROS by P. cuspidatum extract restored senescence-associated phenotypes and enhanced skin protection. Then, we identified polydatin as the active ingredient of P. cuspidatum extract that exhibited antioxidant effects. Polydatin, which contains stilbenoid polyphenols that act as singlet oxygen scavengers through redox reactions, increased OXPHOS efficiency and subsequently restored senescence-associated phenotypes. In summary, our data confirmed the effects of P. cuspidatum extract on senescence rejuvenation and skin protection through ROS reduction. This novel finding may be used as a treatment in senescence rejuvenation in clinical and cosmetic fields.

Inorganic nanoparticles incorporated with transdermal drug delivery systems

INTRODUCTION

Transdermal drug delivery (TDD) is becoming more recognized as a noninvasive method particularly suitable for vulnerable populations. TDD offers an alternative to oral drug delivery, bypassing issues related to poor absorption and metabolism. However, the application of TDD is limited to a few drugs due to the skin's barrier. Various techniques, including passive methods like nanoparticles (NPs), are being explored to enhance drug permeability through the skin.

AREAS COVERED

This review shows the benefit of incorporating inorganic NPs with TDD in improving drug delivery through the skin. Despite the potential of these techniques, there are currently only a few research studies that utilize them. This review addresses the scarcity of research incorporating inorganic NPs with TDD. It also aims to summarize both inorganic NPs and TDD in the pharmaceutical industry, highlighting the advantages of incorporating these novel drug delivery systems with each other.

EXPERT OPINION

Given the potential benefits of incorporating inorganic NPs into TDD systems, there is a need for increased research and attention in this area. The review encourages scientists to address the existing research gap and explore the advantages of combining these innovative drug delivery systems to advance the field.

Assessing Barrier Function in Psoriasis and Cornification Models of Artificial Skin Using Non-Invasive Impedance Spectroscopy

Reconstructed epidermal equivalents (REEs) consist of two distinct cell layers - the stratum corneum (SC) and the keratinocyte layer (KL). The interplay of these layers is particularly crucial in pruritic inflammatory disorders, like psoriasis, where a defective SC barrier is associated with immune dysregulation. However, independent evaluation of the skin barrier function of the SC and KL in REEs is highly challenging because of the lack of quantitative methodologies that do not disrupt the counter layer. Here, a non-invasive impedance spectroscopy technique is introduced for dissecting the distinct contributions of the SC and KL to overall skin barrier function without disrupting the structure. These findings, inferred from the impedance spectra, highlight the individual barrier resistances and maturation levels of each layer. Using an equivalent circuit model, a correlation between impedance parameters and specific skin layers, offering insights beyond traditional impedance methods that address full-thickness skin only is established. This approach successfully detects subtle changes, such as increased paracellular permeability due to mild irritants and the characterization of an immature SC in psoriatic models. This research has significant implications, paving the way for detailed mechanistic investigations and fostering the development of therapies for skin irritation and inflammatory disorders.

Gut-derived wild blueberry phenolic acid metabolites modulate extrinsic cutaneous damage

As the first line of defense, the skin is equipped with various physiological mechanisms positioned to prevent incoming oxidative damage from numerous environmental insults. With persistent exposure to the environment, understanding ways to augment the skin defenses is paramount in protecting from premature aging. In this study, we investigated the ability of five dietary phenolic metabolites, typically found in the bloodstream after wild blueberry consumption, to successfully defend the skin from UV light exposure in a novel ex vivo co-culture model of human skin explants and primary endothelial cells. Skin explants, placed in transwell inserts, were exposed to UV, and subsequently co-cultured with endothelial cells. When the endothelial cells had been pretreated with the bioactive metabolites at physiological concentrations (hippuric acid 3000 nM, isoferulic acid 1000 nM, salicylic acid 130 nM, benzoic acid 900 nM, α-hydroxyhippuric acid 400 nM) cutaneous damage was prevented on the co-cultured with UV-challenged skin explants. Co-culture with non-pretreated endothelial cells did not protect skin explants. Specifically, the pretreatment was able to reduce skin lipid peroxidation (measured as 4-hydroxynonenal protein adducts), and pro-inflammatory enzymes such as cyclooxygenase 2 (COX-2) and NADPH oxidase 4 (NOX-4). Furthermore, pretreatment with the metabolites prevented UV-induced release of inflammatory cytokines such as IL-1β and IL-8 as well as nitric oxides (NO) levels. In addition, the metabolites showed an impressive ability to prevent the loss of cutaneous structural proteins including involucrin and collagen type 1. Of note, endothelial cells cultured with UV exposed skin explants exhibited increased oxidative stress demonstrated by heme oxygenase-1 (HO-1) up-regulation which was significantly prevented in the metabolite treated models. These findings highlight the ability of dietary polyphenolic metabolites to improve cutaneous defenses against extrinsic stressors.

Exploring New Frontiers: Innovations and Therapeutic Targets in Dermatology

The focus of dermatology has increasingly shifted towards exploring new and innovative approaches [...].

Skin-on-a-chip technologies towards clinical translation and commercialization

Skin is the largest organ of the human body which plays a critical role in thermoregulation, metabolism (e.g. synthesis of vitamin D), and protection of other organs from environmental threats, such as infections, microorganisms, ultraviolet radiation, and physical damage. Even though skin diseases are considered to be less fatal, the ubiquity of skin diseases and irritation caused by them highlights the importance of skin studies. Furthermore, skin is a promising means for transdermal drug delivery, which requires a thorough understanding of human skin structure. Current animal andin vitrotwo/three-dimensional skin models provide a platform for disease studies and drug testing, whereas they face challenges in the complete recapitulation of the dynamic and complex structure of actual skin tissue. One of the most effective methods for testing pharmaceuticals and modeling skin diseases are skin-on-a-chip (SoC) platforms. SoC technologies provide a non-invasive approach for examining 3D skin layers and artificially creating disease models in order to develop diagnostic or therapeutic methods. In addition, SoC models enable dynamic perfusion of culture medium with nutrients and facilitate the continuous removal of cellular waste to further mimic thein vivocondition. Here, the article reviews the most recent advances in the design and applications of SoC platforms for disease modeling as well as the analysis of drugs and cosmetics. By examining the contributions of different patents to the physiological relevance of skin models, the review underscores the significant shift towards more ethical and efficient alternatives to animal testing. Furthermore, it explores the market dynamics ofin vitroskin models and organ-on-a-chip platforms, discussing the impact of legislative changes and market demand on the development and adoption of these advanced research tools. This article also identifies the existing obstacles that hinder the advancement of SoC platforms, proposing directions for future improvements, particularly focusing on the journey towards clinical adoption.

3D printing redefines microneedle fabrication for transdermal drug delivery

Microneedles (MNs) have emerged as an innovative, virtually painless technique for intradermal drug delivery. However, the complex and costly fabrication process has limited their widespread accessibility, especially for individuals requiring frequent drug administration. This study introduces a groundbreaking and cost-effective method for producing MNs utilizing fused deposition modeling (FDM) 3D printing technology to enhance transdermal drug delivery. The proposed fabrication process involves the elongation of molten polylactic acid (PLA) filaments to create meticulously designed conoid and neiloid MNs with smooth surfaces. This study underscores the critical role of printing parameters, particularly extrusion length and printing speed, in determining the shape of the MNs. Notably, the conoid-shaped MNs exhibit exceptional skin-penetrating capabilities. In order to evaluate their effectiveness, the MNs were tested on a polydimethylsiloxane (PDMS) skin model for skin penetration. The results highlight the high potential of 3D-printed MNs for transdermal drug administration. This novel approach capitalizes on the benefits of 3D printing technology to fabricate MNs that hold the promise of transforming painless drug administration for a variety of medical applications.

Efficacy of fractional carbon dioxide laser-assisted drug delivery in the management of post-burn scars - A prospective study

Objectives

The objective of our study is to assess the efficacy of fractional carbon dioxide (CO2) laser-assisted drug delivery (LADD) in the management of post-burn scars.

Material and Methods

It is a prospective study conducted from March 2021 to February 2022, with 32 patients ranging in age from 9 to 52 years. The scars lasted anywhere from 6 months to 18 years. The ethical clearance of the Institutional Ethics Committee was obtained. The patient's median age was 22 (range, 09-52). Patients were assessed using a modified Vancouver scar scale (mVSS) score before and after receiving fractional CO2 laser at monthly intervals.

Results

After one treatment, statistically significant improvements in pigment, thickness, and pliability were seen according to the mVSS scores, and these improvements persisted through the final laser session.

Conclusion

Our study has demonstrated that fractional CO2 LADD seems to be an encouraging approach in the management of post-burn scars with good patient satisfaction.

Nanostructure-Mediated Transport of Therapeutics through Epithelial Barriers

The ability to precisely treat human disease is facilitated by the sophisticated design of pharmacologic agents. Nanotechnology has emerged as a valuable approach to creating vehicles that can specifically target organ systems, effectively traverse epithelial barriers, and protect agents from premature degradation. In this review, we discuss the molecular basis for epithelial barrier function, focusing on tight junctions, and describe different pathways that drugs can use to cross barrier-forming tissue, including the paracellular route and transcytosis. Unique features of drug delivery applied to different organ systems are addressed: transdermal, ocular, pulmonary, and oral delivery. We also discuss how design elements of different nanoscale systems, such as composition and nanostructured architecture, can be used to specifically enhance transepithelial delivery. The ability to tailor nanoscale drug delivery vehicles to leverage epithelial barrier biology is an emerging theme in the pursuit of facilitating the efficacious delivery of pharmacologic agents.

Laser-mediated Solutions: Breaking Barriers in Transdermal Drug Delivery

Skin diseases pose challenges in treatment due to the skin's complex structure and protective functions. Topical drug delivery has emerged as a preferred method for treating these conditions, offering localized therapy with minimal systemic side effects. However, the skin's barrier properties frequently limit topical treatments' efficacy by preventing drug penetration into deeper skin layers. In recent years, laser-assisted drug delivery (LADD) has gained attention as a promising strategy to overcome these limitations. LADD involves using lasers to create microchannels in the skin, facilitating the deposition of drugs and enhancing their penetration into the target tissue. Several lasers, such as fractional CO2, have been tested to see how well they work at delivering drugs. Despite the promising outcomes demonstrated in preclinical and clinical studies, several challenges persist in implementing LADD, including limited penetration depth, potential tissue damage, and the cost of LADD systems. Furthermore, selecting appropriate laser parameters and drug formulations is crucial to ensuring optimal therapeutic outcomes. Nevertheless, LADD holds significant potential for improving treatment efficacy for various skin conditions, including skin cancers, scars, and dermatological disorders. Future research efforts should focus on optimizing LADD techniques, addressing safety concerns, and exploring novel drug formulations to maximize the therapeutic benefits of this innovative approach. With continued advancements in laser technology and pharmaceutical science, LADD has the potential to revolutionize the field of dermatology and enhance patient care.

Investigating the Free Volumes as Nanospaces in Human Stratum Corneum Lipid Bilayers Using Positron Annihilation Lifetime Spectroscopy (PALS)

This work is the first one that provides not only evidence for the existence of free volumes in the human stratum corneum but also focuses on comparing these experimental data, obtained through the unique positron annihilation lifetime spectroscopy (PALS) method, with theoretical values published in earlier works. The mean free volume of 0.269 nm was slightly lower than the theoretical value of 0.4 nm. The lifetime τ3 (1.83 ns with a coefficient of variation CV of 3.21%) is dependent on the size of open sites in the skin. This information was used to calculate the free volume radius R (0.269 nm with CV 2.14%), free volume size Vf (0.081 nm3 with CV 4.69%), and the intensity I3 (9.01% with CV 10.94%) to estimate the relative fractional free volume fv (1.32 a.u. with CV 13.68%) in human skin ex vivo. The relation between the lifetime of o-Ps (τ3) and the radius of free volume (R) was formulated using the Tao-Eldrup model, which assumes spherical voids and applies to sites with radii smaller than 1 nm. The results indicate that PALS is a powerful tool for confirming the existence of free volumes and determining their size. The studies also focused on describing the probable locations of these nanospaces in SC lipid bilayers. According to the theory, these play an essential role in dynamic processes in biological systems, including the diffusion of low-molecular-weight hydrophobic and moderately hydrophilic molecules. The mechanism of their formation has been determined by the molecular dynamics of the lipid chains.

Arc-poration improves transdermal delivery of biomolecules

BACKGROUND

To increase skin permeability, various transdermal delivery techniques have been developed. However, due to the stratum corneum as a skin barrier, transdermal delivery remains limited.

AIMS

In this study, we evaluated efficacy and safety of arc-poration as a novel technique disrupting the stratum corneum.

RESULTS

Optical images and histological analysis using reconstituted human skin and porcine skin showed that the treatment of arc-poration created micropores with an average diameter of approximately 100 μm only to the depth of the stratum corneum, but not viable epidermis. In addition, the Franz diffusion cell experiment using reconstituted human skin showed a remarkable increase in permeability following pretreatment with arc-poration. Clinical results clearly demonstrated the enhancement of the skin-improving effect of cosmetics by pretreatment of arc-poration in terms of gloss, hydration, flakiness, texture, tone, tone evenness, and pigmentation of skin, without causing abnormal skin responses. The concentration of ozone and nitrogen oxides generated by arc-poration was below the permissible value for the human body.

CONCLUSIONS

Arc-poration can increase skin permeability by creating stratum corneum-specific micropores, which can enhance the skin-improving effect of cosmetics without adverse responses.

Navigating the future: Microfluidics charting new routes in drug delivery

Microfluidics has emerged as a transformative force in the field of drug delivery, offering innovative avenues to produce a diverse range of nano drug delivery systems. Thanks to its precise manipulation of small fluid volumes and its exceptional command over the physicochemical characteristics of nanoparticles, this technology is notably able to enhance the pharmacokinetics of drugs. It has initiated a revolutionary phase in the domain of drug delivery, presenting a multitude of compelling advantages when it comes to developing nanocarriers tailored for the delivery of poorly soluble medications. These advantages represent a substantial departure from conventional drug delivery methodologies, marking a paradigm shift in pharmaceutical research and development. Furthermore, microfluidic platformsmay be strategically devised to facilitate targeted drug delivery with the objective of enhancing the localized bioavailability of pharmaceutical substances. In this paper, we have comprehensively investigated a range of significant microfluidic techniques used in the production of nanoscale drug delivery systems. This comprehensive review can serve as a valuable reference and offer insightful guidance for the development and optimization of numerous microfluidics-fabricated nanocarriers.

Photonics-powered augmented reality skin electronics for proactive healthcare: multifaceted opportunities

Rapid technological advancements have created opportunities for new solutions in various industries, including healthcare. One exciting new direction in this field of innovation is the combination of skin-based technologies and augmented reality (AR). These dermatological devices allow for the continuous and non-invasive measurement of vital signs and biomarkers, enabling the real-time diagnosis of anomalies, which have applications in telemedicine, oncology, dermatology, and early diagnostics. Despite its many potential benefits, there is a substantial information vacuum regarding using flexible photonics in conjunction with augmented reality for medical purposes. This review explores the current state of dermal augmented reality and flexible optics in skin-conforming sensing platforms by examining the obstacles faced thus far, including technical hurdles, demanding clinical validation standards, and problems with user acceptance. Our main areas of interest are skills, chiroptical properties, and health platform applications, such as optogenetic pixels, spectroscopic imagers, and optical biosensors. My skin-enhanced spherical dichroism and powerful spherically polarized light enable thorough physical inspection with these augmented reality devices: diabetic tracking, skin cancer diagnosis, and cardiovascular illness: preventative medicine, namely blood pressure screening. We demonstrate how to accomplish early prevention using case studies and emergency detection. Finally, it addresses real-world obstacles that hinder fully realizing these materials' extraordinary potential in advancing proactive and preventative personalized medicine, including technical constraints, clinical validation gaps, and barriers to widespread adoption.

Nanotechnology strategies to address challenges in topical and cellular delivery of siRNAs in skin disease therapy

Gene therapy is one of the most advanced therapies in current medicine. In particular, interference RNA-based therapy by small interfering RNA (siRNA) has gained attention in recent years as it is a highly versatile, selective and specific therapy. In dermatological conditions, topical delivery of siRNA offers numerous therapeutic advantages, mainly by inhibiting the expression of target transcripts directly in the skin. However, crossing the stratum corneum and overcoming intracellular barriers is an inherent challenge. Substantial efforts by scientists have moved towards the use of multimodal and multifunctional nanoparticles to overcome these barriers and achieve greater bioavailability in their site of action, the cytoplasm. In this review the most innovative strategies based on nanoparticle and physical methods are presented, as well as the design principles and the main factors that contribute to the performance of these systems. This review also highlights the synergistic contributions of medicine, nanotechnology, and molecular biology to advancing translational research into siRNA-based therapeutics for skin diseases.

E-Tattoos: Toward Functional but Imperceptible Interfacing with Human Skin

The human body continuously emits physiological and psychological information from head to toe. Wearable electronics capable of noninvasively and accurately digitizing this information without compromising user comfort or mobility have the potential to revolutionize telemedicine, mobile health, and both human-machine or human-metaverse interactions. However, state-of-the-art wearable electronics face limitations regarding wearability and functionality due to the mechanical incompatibility between conventional rigid, planar electronics and soft, curvy human skin surfaces. E-Tattoos, a unique type of wearable electronics, are defined by their ultrathin and skin-soft characteristics, which enable noninvasive and comfortable lamination on human skin surfaces without causing obstruction or even mechanical perception. This review article offers an exhaustive exploration of e-tattoos, accounting for their materials, structures, manufacturing processes, properties, functionalities, applications, and remaining challenges. We begin by summarizing the properties of human skin and their effects on signal transmission across the e-tattoo-skin interface. Following this is a discussion of the materials, structural designs, manufacturing, and skin attachment processes of e-tattoos. We classify e-tattoo functionalities into electrical, mechanical, optical, thermal, and chemical sensing, as well as wound healing and other treatments. After discussing energy harvesting and storage capabilities, we outline strategies for the system integration of wireless e-tattoos. In the end, we offer personal perspectives on the remaining challenges and future opportunities in the field.

Application of Biomaterials in the Development of Hydrogel-Forming Microneedles Integrated with a Cyclodextrin Drug Reservoir for Improved Pharmacokinetic Profiles of Telmisartan

Telmisartan (TEL) is a promising antihypertensive agent among other angiotensin receptor blockers. However, its oral application is limited by its poor water solubility. This study presents the successful utilization of biomaterial-based hydrogel-forming microneedles integrated with a direct compressed tablet reservoir (HFMN-DCT) for the transdermal delivery of telmisartan in the treatment of hypertension. The combination of PVP, PVA, and tartaric acid was used in the HFMN formulation. A range of cross-linking temperatures and times were employed to optimize the characteristics of the HFMN. The HFMN exhibited excellent swelling capacity, mechanical strength, and insertion properties. Additionally, the poorly soluble characteristic of TEL was improved by the inclusion complex formulation with β-cyclodextrin (βCD). Phase solubility analysis showed an Ap-type diagram, indicating a higher-order complex between TEL and βCD, with respect to βCD. A ratio of TEL:βCD of 1:4 mM demonstrates the highest solubility enhancement of TEL. The inclusion complex formation was confirmed by FTIR, XRD, DSC, and molecular docking studies. A significantly higher release of TEL (up to 20-fold) from the inclusion complex was observed in the in vitro release study. Subsequently, a DCT reservoir was developed using various concentrations of sodium starch glycolate. Essentially, both the HFMN and DCT reservoir exhibit hemocompatibility and did not induce any skin irritation. The optimized combination of the HFMN-DCT reservoir showed an ex vivo permeation profile of 83.275 ± 2.405%. Notably, the proposed system showed superior pharmacokinetic profiles in the in vivo investigation using male Wistar rats. Overall, this study highlights the potential of HFMN-DCT reservoir systems as a versatile platform for transdermal drug delivery applications.

Comparative immunohistochemical analysis suggests a conserved role of EPS8L1 in epidermal and hair follicle barriers of mammals

The mammalian skin and its appendages depend on tightly coordinated differentiation of epithelial cells. Epidermal growth factor receptor (EGFR) pathway substrate 8 (EPS8) like 1 (EPS8L1) is enriched in the epidermis among human tissues and has also been detected in the epidermis of lizards. Here, we show by the analysis of single-cell RNA-sequencing data that EPS8L1 mRNA is co-expressed with filaggrin and loricrin in terminally differentiated human epidermal keratinocytes. Comparative genomics indicated that EPS8L1 is conserved in all main clades of mammals, whereas the orthologous gene has been lost in birds. Using a polyclonal antibody against EPS8L1, we performed an immunohistochemical screening of skin from diverse mammalian species and immuno-electron microscopy of human skin. EPS8L1 was detected predominantly in the granular layer of the epidermis in monotremes, marsupial, and placental mammals. The labeling was partly associated with cell membranes, and it was evident along the perimeter of keratinocytes at the transition with the cornified layer of the epidermis, similar to involucrin distribution. Basal, spinous, and the fully mature cornified layers lacked immunolabeling of EPS8L1. In addition to the epidermis, the hair follicle inner root sheath (IRS) was immunolabeled. Both epidermal granular layer and IRS contribute to the barrier function of the skin, suggesting that EPS8L1 is involved in the regulation of these barriers.

Penetration of topically applied polymeric nanoparticles across the epidermis of thick skin from rat

The barrier function of the epidermis poses a significant challenge to nanoparticle-mediated topical delivery. A key factor in this barrier function is the thickness of the stratum corneum (SC) layer within the epidermis, which varies across different anatomical sites. The epidermis from the palms and soles, for instance, have thicker SC compared to those from other areas. Previous studies have attempted to bypass the SC layer for nanoparticle penetration by using physical disruption; however, these studies have mostly focused on non-thick skin. In this study, we investigate the role of SC-disrupting mechano-physical strategies (tape-stripping and microneedle abrasion) on thick and thin skin, in allowing transdermal penetration of topically applied nanoparticles using an ex-vivo skin model from rat. Our findings show that tape-stripping reduced the overall thickness of SC in thick skin by 87%, from 67.4 ± 17.3μm to 8.2 ± 8.5μm, whereas it reduced thin skin SC by only 38%, from 9.9 ± 0.6μm to 6.2 ± 3.2μm. Compared to non-thick skin, SC disruption in thick skin resulted in higher nanoparticle diffusion. Tape-stripping effectively reduces SC thickness of thick skin and can be potentially utilized for enhanced penetration of topically applied nanoparticles in skin conditions that affect thick skin.

Development of a mini pig model of peanut allergy

Introduction

The prevalence of peanut allergies is increasing, emphasizing the need for an animal model to enhance our understanding of peanut allergy pathogenesis and to advance diagnostic tools and therapeutic interventions. While mice are frequently used as model organisms, their allergic responses do not fully mirror those observed in humans, warranting the exploration of a higher animal model. The porcine gastrointestinal system closely resembles that of humans, and exhibits allergy symptoms akin to human responses, making pigs a promising model for peanut allergy research.

Methods

In this study we compared two allergen sensitization protocols involving either topical allergen application after repeated tape stripping (TS) or intraperitoneal (IP) injections to induce peanut-specific allergy and anaphylaxis reactions in mini pigs. Mini pigs sensitized with a combination of peanut protein extract (PE) and cholera toxin (CT) through either the IP or the TS route.

Results

Sensitized pigs via both methods developed systemic PE-specific IgG and IgE responses. Following peanut challenge via the IP route, both TS- and IP-sensitized pigs displayed allergy symptoms, including lethargy, skin rashes, vomiting, and a drop in body temperature. However, respiratory distress was observed exclusively in pigs sensitized through the TS route and not in those sensitized through the IP route. However, it is noteworthy that both groups of sensitized pigs maintained peanut hypersensitivity for up to two months post-sensitization, albeit with a reduction in the severity of allergy symptoms. Importantly, both groups exhibited sustained levels of PE-specific IgG, IgE, and elevated concentrations of mast cell protease in their blood following the IP challenges.

Discussion

Overall, this study reports TS and IP as two different modes of sensitization leading to onset of peanut specific allergic reactions in mini pigs, but only the TS-sensitization led to systemic anaphylaxis (simultaneous presence of symptoms: breathing difficulty, intense skin rash, and impaired mobility). A distinctive feature of these sensitization protocols is the 100% success rate (N = 4 pigs per group) in sensitizing the subjects.

The effect of electrical stimulation on skin vulnerability to irritants

PURPOSE

Electrical stimulation (ES) is a widely used technique in the medical field for various purposes. The effect of ES on several skin properties has been investigated; however, its effect on skin vulnerability to irritants remains unknown. This study aimed to investigate the effects of ES application on skin vulnerability to external irritants.

MATERIALS AND METHODS

An experimental study on 12 healthy male subjects (Mean ± SD, 22.9 ± 3.6 years) who completed the study. The subjects were free of skin abnormalities in the volar aspect of both forearms. Three areas were allocated to each forearm and marked as areas 1, 2, and A in the treated forearm, and areas 3, 4, and B in the control forearm. ES was applied to the volar aspect of the treated forearm for 30 min three times a week, for 2 weeks. The effect of ES on skin vulnerability was investigated using 5% and 0.5% sodium lauryl sulfate (SLS) patches applied to both treated and control forearms. The skin response to irritants was evaluated using transepidermal water loss (TEWL) and a visual erythema score 24 h after patch removal.

RESULTS

Compared to the control forearm, ES increased skin permeability and erythema in response to external irritants (SLS), as measured by the visual analog score (Z = 2.75, p = 0.006) and TEWL (p < 0.05), respectively.

CONCLUSIONS

ES escalates skin reactions to low concentrations of irritant substances, such as SLS, in the area between the two electrodes. This emphasizes the use of this substance, and similar irritants should be avoided in areas treated with ES.

Novel 40 µm spot size 3050/3200 nm DFG laser versus CO2 laser for laser-assisted drug delivery

BACKGROUND AND OBJECTIVES

The use of ablative fractional lasers to enhance the delivery of topical drugs through the skin is known as laser-assisted drug delivery. Here, we compare a novel 3050/3200 nm difference frequency generation (DFG) fiber laser (spot size: 40 µm) to a commercially used CO2 laser (spot size: 120 µm). The objective is to determine whether differences in spot size and coagulation zone (CZ) thickness influence drug uptake.

MATERIALS AND METHODS

Fractional ablation was performed on ex-vivo human abdominal skin with the DFG (5 mJ) and CO2 (12 mJ) lasers to generate 680 µm deep lesions. To evaluate drug delivery, 30 kDa encapsulated fluorescent dye was topically applied to the skin and histologically analyzed at skin depths of 100, 140, 200, 400, and 600 µm. Additionally, transcutaneous permeation of encapsulated and 350 Da nonencapsulated dye was assessed using Franz Cells.

RESULTS

The DFG laser generated smaller channels (diameter: 56.5 µm) with thinner CZs (thickness: 22.4 µm) than the CO2 laser (diameter: 75.9 µm, thickness: 66.8 µm). The DFG laser treated group exhibited significantly higher encapsulated dye total fluorescence intensities after 3 h compared to the CO2 laser treated group across all skin depths (p < 0.001). Permeation of nonencapsulated dye was also higher in the DFG laser treated group vs the CO2 laser treated group after 48 h (p < 0.0001), while encapsulated dye was not detected in any group.

CONCLUSION

The DFG laser treated skin exhibited significantly higher total fluorescence uptake compared to the CO2 laser. Additionally, the smaller spot size and thinner CZ of the DFG laser could result in faster wound healing and reduced adverse effects while delivering similar or greater amount of topically applied drugs.

Fabrication of controlled-release polymeric microneedles containing progesterone-loaded self-microemulsions for transdermal delivery

Progesterone (PG) has been approved for hormone replacement therapy to mitigate the risk of endometrial carcinoma. However, there has been a lack of success in oral PG due to its rapid degradation. Transdermal PG has advantages but lacks efficacy due to its poor solubility (Log p = 3.9). Therefore, this study aimed to evaluate how combining self-microemulsifying drug delivery systems (SMEDDS) and polymeric microneedles (MNs) could improve the transdermal delivery of PG in a controlled-release manner. Among PG-SMEDDS, PG-SME5 was selected for its desirable properties and stability. The two-layer polymeric MNs formulation incorporating PG-SME5 (PG-SMEDDS-tMNs) was formulated from aqueous blends of polymers as a first layer and 20% PCL as a second layer. It successfully penetrated neonatal porcine skin with the dissolution of the first layer observed within 15 min after application. In vitro skin permeation revealed that the percentage of PG which permeated the skin over 82 h using PG-SMEDDS-tMNs was higher than a PG-suspension and PG-SMEDDS. The Higuchi kinetic showed controlled release over 15 days of PG from PG-SMEDDS-tMNs. These studies suggested that incorporating PG-SMEDDS into controlled-release two-layer polymeric MNs could be a promising approach for improving the transdermal delivery of PG.

Novel Vesicular Bilosomal Delivery Systems for Dermal/Transdermal Applications

The application of therapeutically active molecules through the dermal/transdermal route into the skin has evolved as an attractive formulation strategy in comparison to oral delivery systems for the treatment of various disease conditions. However, the delivery of drugs across the skin is limited due to poor permeability. Dermal/transdermal delivery is associated with ease of accessibility, enhanced safety, better patient compliance, and reduced variability in plasma drug concentrations. It has the ability to bypass the first-pass metabolism, which ultimately results in steady and sustained drug levels in the systemic circulation. Vesicular drug delivery systems, including bilosomes, have gained significant interest due to their colloidal nature, improved drug solubility, absorption, and bioavailability with prolonged circulation time for a large number of new drug molecules. Bilosomes are novel lipid vesicular nanocarriers comprising bile salts, such as deoxycholic acid, sodium cholate, deoxycholate, taurocholate, glycocholate or sorbitan tristearate. These bilosomes are associated with high flexibility, deformability, and elasticity attributed to their bile acid component. These carriers are advantageous in terms of improved skin permeation, increased dermal and epidermal drug concentration, and enhanced local action with reduced systemic absorption of the drug, resulting in reduced side effects. The present article provides a comprehensive overview of the biopharmaceutical aspects of dermal/transdermal bilosome delivery systems, their composition, formulation techniques, characterization methods, and applications.

Skin delivery of synthetic benzoyl pterostilbenes suppresses atopic dermatitis-like inflammation through the inhibition of keratinocyte and macrophage activation

Atopic dermatitis (AD) is one of the most common skin autoimmune diseases needing continuous anti-inflammatory management. Pterostilbene is reported to exhibit anti-inflammatory activity with higher bioavailability and stability than its parent compound, resveratrol. In this study, a series of synthetic pterostilbene analogs were designed by the hybridization of pterostilbene with chalcones or benzoyl chloride. Seventeen analogs derived from pterostilbene were synthesized with differences in the positions of hydroxyl, methoxyl, or fluoro moieties. These compounds were screened by the inhibitory effect on the overexpressed Th2-associated cytokines/chemokines in the activated human keratinocytes (HaCaT). The anti-IL-5 and anti-CCL5 activity of these compounds led to the identification of three effective compounds: 3a ((E)- 4-(3,5-dimethoxystyryl)phenyl benzoate), 3d ((E)- 4-(3,5-dimethoxystyryl)phenyl 2-methoxybenzoate), and 3g ((E)- 4-(3,5-dimethoxystyryl)phenyl 2-fluorobenzoate). These benzoyl pterostilbenes also significantly decreased Th1/Th17-associated proinflammatory mediators in the activated macrophages (differentiated THP-1). The result showed that the conditioned medium of benzoyl pterostilbene-treated macrophages reduced the phosphorylated STAT3 in the keratinocytes, indicating the blockade of crosstalk between resident and immune cells. Compounds 3d and 3g generally showed greater skin absorption than 3a. The flux of 3g across barrier-defective skins mimicking the AD skin was 3-fold higher than that of across intact skin. The dinitrochlorobenzene (DNCB)-induced AD mouse model manifested that topical delivery with 3g improved the pathological signs through inhibiting cytokines/chemokines (IL-5, TNF-α, CCL17, and CCL22) and macrophage recruitment. The epidermal thickness was reduced from 76 to 55 µm after topical 3g delivery. The therapeutic activity of 3g was comparable to that of tacrolimus (TAC) used as a positive control. The benzoyl pterostilbenes attenuated the inflammation via the MAPK and c-Jun signaling. Furthermore, this study provided experimental evidence of benzoyl pterostilbene analogs for therapeutic potential on AD.

Visualization of Nanocarriers and Drugs in Cells and Tissue

In this chapter, the visualization of nanocarriers and drugs in cells and tissue is reviewed. This topic is tightly connected to modern drug delivery, which relies on nanoscopic drug formulation approaches and the ability to probe nanoparticulate systems selectively in cells and tissue using advanced spectroscopic and microscopic techniques. We first give an overview of the breadth of this research field. Then, we mainly focus on topical drug delivery to the skin and discuss selected visualization techniques from spectromicroscopy, such as scanning transmission X-ray microscopy and fluorescence lifetime imaging. These techniques rely on the sensitive and quantitative detection of the topically applied drug delivery systems and active substances, either by exploiting their molecular properties or by introducing environmentally sensitive probes that facilitate their detection.

Microphysiological Constructs and Systems: Biofabrication Tactics, Biomimetic Evaluation Approaches, and Biomedical Applications

In recent decades, microphysiological constructs and systems (MPCs and MPSs) have undergone significant development, ranging from self-organized organoids to high-throughput organ-on-a-chip platforms. Advances in biomaterials, bioinks, 3D bioprinting, micro/nanofabrication, and sensor technologies have contributed to diverse and innovative biofabrication tactics. MPCs and MPSs, particularly tissue chips relevant to absorption, distribution, metabolism, excretion, and toxicity, have demonstrated potential as precise, efficient, and economical alternatives to animal models for drug discovery and personalized medicine. However, current approaches mainly focus on the in vitro recapitulation of the human anatomical structure and physiological-biochemical indices at a single or a few simple levels. This review highlights the recent remarkable progress in MPC and MPS models and their applications. The challenges that must be addressed to assess the reliability, quantify the techniques, and utilize the fidelity of the models are also discussed.

Unraveling the Multifaceted Roles of Extracellular Vesicles: Insights into Biology, Pharmacology, and Pharmaceutical Applications for Drug Delivery

Extracellular vesicles (EVs) are nanoparticles released from various cell types that have emerged as powerful new therapeutic option for a variety of diseases. EVs are involved in the transmission of biological signals between cells and in the regulation of a variety of biological processes, highlighting them as potential novel targets/platforms for therapeutics intervention and/or delivery. Therefore, it is necessary to investigate new aspects of EVs' biogenesis, biodistribution, metabolism, and excretion as well as safety/compatibility of both unmodified and engineered EVs upon administration in different pharmaceutical dosage forms and delivery systems. In this review, we summarize the current knowledge of essential physiological and pathological roles of EVs in different organs and organ systems. We provide an overview regarding application of EVs as therapeutic targets, therapeutics, and drug delivery platforms. We also explore various approaches implemented over the years to improve the dosage of specific EV products for different administration routes.

Emerging drug delivery systems with traditional routes - A roadmap to chronic inflammatory diseases

Inflammation is prevalent and inevitable in daily life but can generally be accommodated by the immune systems. However, incapable self-healing and persistent inflammation can progress to chronic inflammation, leading to prevalent or fatal chronic diseases. This review comprehensively covers the topic of emerging drug delivery systems (DDSs) for the treatment of chronic inflammatory diseases (CIDs). First, we introduce the basic biology of the chronic inflammatory process and provide an overview of the main CIDs of the major organs. Next, up-to-date information on various DDSs and the associated strategies for ensuring targeted delivery and stimuli-responsiveness applied to CIDs are discussed extensively. The implementation of traditional routes of drug administration to maximize their therapeutic effects against CIDs is then summarized. Finally, perspectives on future DDSs against CIDs are presented.

New Horizons in Dermal and Transdermal Drug Delivery Systems

Dermal and transdermal drug delivery represents an important strategy to target drugs towards the site of action or to noninvasively enhance treatment activity, circumventing the hepatic first passage and reducing toxicity [...].

In silico molecular docking, molecular dynamics, ADMET analysis of fucoidan against receptor frizzled-8 and coreceptor LRP6 in Wnt/β-Catenin pathway and in vitro analysis of fucoidan extract from Sargassum echinocarpum as β-catenin inhibitor in breast cancer cell line (MCF-7)

This study aimed to investigate the effect of fucoidan on the Wnt/β-Catenin pathway using both in-silico molecular docking, molecular dynamics, ADMET analysis (in frizzled-8 receptor and LRP6 coreceptor) and in-vitro experiments using MCF-7 breast cancer cells. Through the molecular docking analysis, the binding energies on the frizzled-8 receptor were -5.6, -5.1, -9.4, and -8.8 kcal/mol, respectively. Meanwhile, those on the LRP6 receptor, were -7.3, -6.2, -10.0, and -9.8 kcal/mol, respectively. The results showed that fucoidan had a favorable binding affinity for both receptors. Furthermore, it was discovered to reduce the interaction and binding affinity between Wnt agonists to frizzled-8 and LRP6 receptors. This reduction was reflected in the change in the binding energy of the fucoidan-Wnt agonist-frizzled 8 and fucoidan-Wnt agonist-LRP6 complexes, which exhibited decreases of -7.0 kcal/mol and -7.8 kcal/mol, respectively. Fucoidan was found stable in complexes with frizzled-8 receptor and co-receptor LRP6. ADMET study showed it's non-carcinogenic and can be distributed in the body. Fucoidan effectively inhibited β-catenin production, a critical factor in the Wnt/β-catenin pathway. The MCF-7 breast cancer cells were treated with fucoidan extract from S. echinocarpum at incubation times of 24, 48, and 72 h, resulting in a reduction of β-catenin levels by 95.19%, 83.88%, and 80.88%, respectively. Fucoidan also shows no significant difference in value compared to fucoidan standard (F. vesiculosus) and doxorubicin. Fucoidan exhibited antiproliferative effects against breast cancer cells, specifically through its modulation of the Wnt/β-Catenin pathway, and held great potential as an herbal anticancer agent.Communicated by Ramaswamy H. Sarma.

Illuminating Insights: Clinical Study Harnessing Pharmacoscintigraphy for Permeation Study of Radiolabeled Nimesulide Topical Formulation in Healthy Human Volunteers

An alternative to oral administration for the delivery of therapeutic substances is the topical route, which frequently has comparable efficacy but may have a better tolerability profile. Gamma scintigraphy is a noninvasive technique that involves the application of radioactive substances to conduct biodistribution studies of therapeutic substances delivered through various routes. Nimesulide (NSD) was radiolabeled with technetium pertechnetate (Technetium99m [99mTc]) and this radiolabeled drug complex (99mTc-NSD) was used to prepare a topical gel formulation. The permeation of the radiolabeled drug from the topical gel was determined by gamma scintigraphy on human volunteers. The region of interest was calculated for the quantification of permeated radiolabeled drugs. This was observed that the mean percentage permeation of 99mTc-NSD was found to be 0.32 ± 0.22 to 36.37 ± 2.86 at 5 and 240 min. It was demonstrated that gamma scintigraphy may be a noninvasive and reliable technique for the determination of drug permeation through topical routes.