Recent advances in polymeric transdermal drug delivery systems

Tolerability, acceptability, and reproducibility of topical STAR particles in human subjects

Topical delivery to treat dermatological disease is constrained by low skin permeability to most drugs due to the stratum corneum barrier. STAR particles containing microneedle protrusions can be topically applied on the skin to create micropores that dramatically increase skin permeability, even to water-soluble compounds and macromolecules. This study addresses the tolerability, acceptability, and reproducibility of STAR particles rubbed on the skin at multiple pressures and after multiple applications to human subjects. One-time STAR particle application at pressures between 40 and 80 kPa showed that skin microporation and erythema directly correlated with increased pressure, and 83% of subjects reported STAR particles to be comfortable at all pressures. Repeated application of STAR particles for 10 consecutive days at 80 kPa showed that skin microporation (~0.5% of skin area), erythema (low-to-moderate), and comfort with self-administration (75%) were similar over the course of the study. Comfort of sensations associated with STAR particles increased from 58% to 71% during the study, and familiarity with STAR particles increased from 12.5% to 50% of subjects reporting STAR particle application not feeling different from other skin products. This study demonstrates that topically applied STAR particles were well tolerated and highly acceptable after application at various pressures and repeated daily use. These findings further suggest that STAR particles offer a safe and reliable platform to enhance cutaneous drug delivery.

Biphasic drug release from electrospun structures

INTRODUCTION

Biphasic release, as a special drug-modified release profile that combines immediate and sustained release, allows fast therapeutic action and retains blood drug concentration for long periods. Electrospun nanofibers, particularly those with complex nanostructures produced by multi-fluid electrospinning processes, are potential novel biphasic drug delivery systems (DDSs).

AREAS COVERED

This review summarizes the most recent developments in electrospinning and related structures. In this review, the role of electrospun nanostructures in biphasic drug release was comprehensively explored. These electrospun nanostructures include monolithic nanofibers obtained through single-fluid blending electrospinning, core-shell and Janus nanostructures prepared via bifluid electrospinning, three-compartment nanostructures obtained via trifluid electrospinning, nanofibrous assemblies obtained through the layer-by-layer deposition of nanofibers, and the combined structure of electrospun nanofiber mats with casting films. The strategies and mechanisms through which complex structures facilitate biphasic release were analyzed.

EXPERT OPINION

Electrospun structures can provide many strategies for the development of biphasic drug release DDSs. However, many issues such as the scale-up productions of complex nanostructures, the in vivo verification of the biphasic release effects, keeping pace with the developments of multi-fluid electrospinning, drawing support from the state-of-the-art pharmaceutical excipients, and the combination with traditional pharmaceutical methods need to be addressed for real applications.

Potential Role of Innate Lymphoid Cells in the Pathogenesis and Treatment of Skin Diseases

Group 2 innate lymphoid cells (ILC2s) are lymphoid cells that are resident in mucosal tissues, especially the skin, which, once stimulated by epithelial cell-derived cytokines, release IL-5, IL-13, and IL-4, as the effectors of type 2 immune responses. This research aims to evaluate the role of ILC2s in the pathogenesis of skin diseases, with a particular focus on inflammatory cutaneous disorders, in order to also elucidate potential therapeutic perspectives. The research has been conducted in articles, excluding reviews and meta-analyses, on both animals and humans. The results showed that ILC2s play a crucial role in the pathogenesis of systemic skin manifestations, prognosis, and severity, while a potential antimelanoma role is emerging from the new research. Future perspectives could include the development of new antibodies targeting or stimulating ILC2 release. This evidence could add a new therapeutic approach to inflammatory cutaneous conditions, including allergic ones.

Cleanroom-Free Fabrication of Microneedles for Multimodal Drug Delivery

Microneedles have recently emerged as a powerful tool for minimally invasive drug delivery and body fluid sampling. To date, high-resolution fabrication of microneedle arrays (MNAs) is mostly achieved by the utilization of sophisticated facilities and expertise. Particularly, hollow microneedles have usually been manufactured in cleanrooms out of silicon, resin, or metallic materials. Such strategies do not support the fabrication of microneedles from biocompatible/biodegradable materials and limit the capability of multimodal drug delivery for the controlled release of different therapeutics through a combination of injection and sustained diffusion. This study implements low-cost 3D printers to fabricate relatively large needle arrays, followed by repeatable shrink-molding of hydrogels to form high-resolution molds for solid and hollow MNAs with controllable sizes. The developed strategy further enables modulating surface topography of MNAs to tailor their surface area and instantaneous wettability for controllable drug delivery and body fluid sampling. Hybrid gelatin methacryloyl (GelMA)/polyethylene glycol diacrylate (PEGDA) MNAs are fabricated using the developed strategy that can easily penetrate the skin and enable multimodal drug delivery. The proposed method holds promise for affordable, controllable, and scalable fabrication of MNAs by researchers and clinicians for controlled spatiotemporal administration of therapeutics and sample collection.

Transdermal Delivery of Phloretin by Gallic Acid Microparticles

Exposure to ultraviolet (UV) radiation causes harmful effects on the skin, such as inflammatory states and photoaging, which depend strictly on the form, amount, and intensity of UV radiation and the type of individual exposed. Fortunately, the skin is endowed with a number of endogenous antioxidants and enzymes crucial in its response to UV radiation damage. However, the aging process and environmental stress can deprive the epidermis of its endogenous antioxidants. Therefore, natural exogenous antioxidants may be able to reduce the severity of UV-induced skin damage and aging. Several plant foods constitute a natural source of various antioxidants. These include gallic acid and phloretin, used in this work. Specifically, polymeric microspheres, useful for the delivery of phloretin, were made from gallic acid, a molecule that has a singular chemical structure with two different functional groups, carboxylic and hydroxyl, capable of providing polymerizable derivatives after esterification. Phloretin is a dihydrochalcone that possesses many biological and pharmacological properties, such as potent antioxidant activity in free radical removal, inhibition of lipid peroxidation, and antiproliferative effects. The obtained particles were characterized by Fourier transform infrared spectroscopy. Antioxidant activity, swelling behavior, phloretin loading efficiency, and transdermal release were also evaluated. The results obtained indicate that the micrometer-sized particles effectively swell, and release the phloretin encapsulated in them within 24 h, and possess antioxidant efficacy comparable to that of free phloretin solution. Therefore, such microspheres could be a viable strategy for the transdermal release of phloretin and subsequent protection from UV-induced skin damage.

Formulation and Characterization of Ethyl Cellulose-Based Patches Containing Curcumin-Chitosan Nanoparticles for the Possible Management of Inflammation via Skin Delivery

Curcumin, a natural phenolic compound, exhibits poor absorption and extensive first pass metabolism after oral administration. In the present study, curcumin-chitosan nanoparticles (cur-cs-np) were prepared and incorporated into ethyl cellulose patches for the management of inflammation via skin delivery. Ionic gelation method was used for the preparation of nanoparticles. The prepared nanoparticles were evaluated for size, zetapotential, surface morphology, drug content, and % encapsulation efficiency. The nanoparticles were then incorporated into ethyl cellulose-based patches using solvent evaporation technique. ATR-FTIR was used to study/assess incompatibility between drug and excipients. The prepared patches were evaluated physiochemically. The in vitro release, ex vivo permeation, and skin drug retention studies were carried out using Franz diffusion cells and rat skin as permeable membrane. The prepared nanoparticles were spherical, with particle size in the range of 203–229 nm, zetapotential 25–36 mV, and PDI 0.27–0.29 Mw/Mn. The drug content and %EE were 53% and 59%. Nanoparticles incorporated patches are smooth, flexible, and homogenous. The in vitro release and ex vivo permeation of curcumin from nanoparticles were higher than the patches, whereas the skin retention of curcumin was significantly higher in case of patches. The developed patches deliver cur-cs-np into the skin, where nanoparticles interact with skin negative charges and hence result in higher and prolonged retention in the skin. The higher concentration of drug in the skin helps in better management of inflammation. This was shown by anti-inflammatory activity. The inflammation (volume of paw) was significantly reduced when using patches as compared to nanoparticles. It was concluded that the incorporation of cur-cs-np into ethyl cellulose-based patches results in controlled release and hence enhanced anti-inflammatory activity.

Formulation and characterization of thiolated chitosan/polyvinyl acetate based microneedle patch for transdermal delivery of dydrogesterone

Microneedle patches are promising transdermal drug delivery platforms with minimal invasiveness in a painless manner. Microneedle patch could be a promising alternate route for delivery of drugs having poor solubility and low bioavailability. This research work therefore, aimed to develop and characterize microneedle patch of thiolated chitosan (TCS) and polyvinyl acetate (PVA) for the systemic delivery of dydrogesterone (DYD). TCS-PVA-based microneedle patch was fabricated with 225 needles having a length of 575 µm with the sharp pointed end. Different ratios of TCS-PVA-based patch were employed to investigate the effects of mechanical tensile strength and percentage elongation. The scanning electron microscopy (SEM) revealed intact sharp-pointed needles. In vitro dissolution studies of microneedle patch (MN-P) were carried out by modified Franz-diffusion cell revealing the sustained release of DYD 81.45 ± 2.768 % at 48 hrs as compared to pure drug that showed 96.7 ± 1.75 % at 12 hrs. The transport of DYD (81%) across skin reaching the systemic circulation was evaluated through ex vivo permeation studies of MN-P. The skin penetration study through the parafilm M method showed good penetration with no deformation and breakage of needles along with no visible signs of skin irritation. Histological study of mice skins clearly showed the deeper penetration of needles into the skin. In summary, as-prepared MN-P show potential in developing an effective transdermal delivery system for DYD.

Current Advances in Lipid Nanosystems Intended for Topical and Transdermal Drug Delivery Applications

Skin delivery is an exciting and challenging field. It is a promising approach for effective drug delivery due to its ease of administration, ease of handling, high flexibility, controlled release, prolonged therapeutic effect, adaptability, and many other advantages. The main associated challenge, however, is low skin permeability. The skin is a healthy barrier that serves as the body's primary defence mechanism against foreign particles. New advances in skin delivery (both topical and transdermal) depend on overcoming the challenges associated with drug molecule permeation and skin irritation. These limitations can be overcome by employing new approaches such as lipid nanosystems. Due to their advantages (such as easy scaling, low cost, and remarkable stability) these systems have attracted interest from the scientific community. However, for a successful formulation, several factors including particle size, surface charge, components, etc. have to be understood and controlled. This review provided a brief overview of the structure of the skin as well as the different pathways of nanoparticle penetration. In addition, the main factors influencing the penetration of nanoparticles have been highlighted. Applications of lipid nanosystems for dermal and transdermal delivery, as well as regulatory aspects, were critically discussed.

Reliable Kinetics for Drug Delivery with a Microfluidic Device Integrated with the Dialysis Bag

The clinical success of a drug delivery system turns back to performing experiments with more reliable data. The dialysis bag has been one of the most employed technologies to monitor drug release from nanocarriers, membranes, and scaffolds. Unfortunately, this technology has several challenges regarding the accuracy of the obtained results. In this study, the development of a new system by integrating a microfluidic device and dialysis bag named "MF-dialysis" was carried out to evaluate the accuracy of the reported data. The release study was performed focusing on two drug delivery systems: (i) nanocarrier: Artemisia Absinthium extract-loaded soy protein isolate nanoparticle and (ii) sodium alginate film loaded with the nanocarrier. The obtained nanocarrier was analyzed by SEM, DLS, and zeta potential. The final experimental data were modeled using SigmaPlot software. Based on the results, two distinct but fitted models for the dialysis bag (power model, R² = 0.99) and MF-dialysis (exponential model, R² = 0.95) were obtained. MF-dialysis approved that after a while, NPs and films showed more drug release compared to the dialysis bag. To sum up, the MF-dialysis system can be a good candidate for a quick and more reliable study of drug delivery systems.

Recent Advances in Metal-Organic Framework (MOF) Asymmetric Membranes/Composites for Biomedical Applications

Metal-organic frameworks (MOFs) are a new class of porous crystalline materials composed of metal and organic material. MOFs have fascinating properties, such as fine tunability, large specific surface area, and high porosity. MOFs are widely used for environmental protection, biosensors, regenerative medicine, medical engineering, cell therapy, catalysts, and drug delivery. Recent studies have reported various significant properties of MOFs for biomedical applications, such as drug detection and delivery. In contrast, MOFs have limitations such as low stability and low specificity in binding to the target. MOF-based membranes improve the stability and specificity of conventional MOFs by increasing the surface area and developing the possibility of MOF-ligand binding, while conjugated membranes dramatically increase the area of active functional groups. This special property makes them attractive for drug and biosensor fabrication, as both the spreading and solubility components of the porosity can be changed. Asymmetric membranes are a structure with high potential in the biomedical field, due to the different characteristics on its two surfaces, the possibility of adjusting various properties such as the size of porosity, transfer rate and selectivity, and surface properties such as hydrophilicity and hydrophobicity. MOF assisted asymmetric membranes can provide a platform with different properties and characteristics in the biomedical field. The latest version of MOF materials/membranes has several potential applications, especially in medical engineering, cell therapy, drug delivery, and regenerative medicine, which will be discussed in this review, along with their advantages, disadvantages, and challenges.

Combination of ion-pair strategy and chemical enhancers for design of dexmedetomidine long-acting patches: Dual action mechanism induced longer controlled release and better delivery efficiency

The purpose of this study was to prepare a dexmedetomidine (Dex) 72 h long-acting patch by the combined use of ion-pair strategy and chemical enhancers (CEs), and to investigate molecular mechanisms of drug-loading enhancement and controlled release. The formulation of patch was optimized by single-factor investigation and Box-Behnken design. The pharmacokinetics, analgesic pharmacodynamics and irritation of the formulation were evaluated, respectively. Moreover, the effects of ion-pairs and CEs on the patch were characterized by DSC, rheology study, FTIR, and molecular docking, and the effects on the skin were evaluated by Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR), Raman study, and molecular dynamics, respectively. The optimized formulation was 17.00 % (w/w) Dex-NA (Naphthoic acid), 7.20 % Polyglyceryl-3 dioleate (POCC), 25-AAOH as pressure sensitive adhesives (PSA) and 66.50 μm in thickness. Compared with the control group (C_max = 62.02 ± 16.55 ng/mL, MRT_0-t = 26.74 ± 1.27 h), the pharmacokinetics behavior of the optimization group was more stable and durable (C_max = 31.22 ± 13.26 ng/mL, MRT_0-t = 33.62 ± 1.62 h). Besides, it also showed good analgesic effect and no obvious irritation. The results indicated that Dex-NA both increased the drug-PSA interactions and inhibited the penetration of the drug into the skin. POCC increased the molecular mobility of the PSA and disrupted skin lipids thereby improving the drug penetration rate. In summary, the Dex long-acting patch was developed, which provided a reference for the combined application of ion-pair strategy and CEs in other long-acting transdermal delivery.

A review on optimistic development of polymeric nanocomposite membrane on environmental remediation

Current health and environmental concerns about the abundance and drawbacks of municipal wastewater as well as industrial effluent have prompted the development of novel and innovative treatment processes. A global shortage of clean water poses significant challenges to the survival of all life forms. For the removal of both biodegradable and non-biodegradable harmful wastes/pollutants from water, sophisticated wastewater treatment technologies are required. Polymer membrane technology is critical to overcoming this major challenge. Polymer matrix-based nanocomposite membranes are among the most popular in polymer membrane technology in terms of convenience. These membranes and their major components are environmentally friendly, energy efficient, cost effective, operationally versatile, and feasible. This review provides an overview of the drawbacks as well as promising developments in polymer membrane and nanocomposite membranes for environmental remediation, with a focus on wastewater treatment. Additionally, the advantages of nanocomposite membranes such as stability, antimicrobial properties, and adsorption processes have been discussed. The goal of this review was to summarize the remediation of harmful pollutants from water and wastewater/effluent using polymer matrix-based nanocomposite membrane technology, and to highlight its shortcomings and future prospects.

Dissolvable Carboxymethylcellulose Microneedles for Noninvasive and Rapid Administration of Diclofenac Sodium

The aim of this study is to prepare dissolvable biopolymeric microneedle (MN) patches composed solely of sodium carboxymethylcellulose (CMC), a water-soluble cellulose derivative with good film-forming ability, by micromolding technology for the transdermal delivery of diclofenac sodium salt (DCF). The MNs with ≈456 µm in height displayed adequate morphology, thermal stability up to 200 °C, and the required mechanical strength for skin insertion (>0.15 N needle^-1 ). Experiments in ex vivo abdominal human skin demonstrate the insertion capability of the CMC_DCF MNs up to 401 µm in depth. The dissolution of the patches in saline buffer results in a maximum cumulative release of 98% of diclofenac after 40 min, and insertion in a skin simulant reveals that all MNs completely dissolve within 10 min. Moreover, the MN patches are noncytotoxic toward human keratinocytes. These results suggest that the MN patches produced with CMC are promising biopolymeric systems for the rapid administration of DCF in a minimally invasive manner.

A Novel Integrated Transdermal Drug Delivery System with Micropump and Microneedle Made from Polymers

Transdermal drug delivery (TDD), which enables targeted delivery with microdosing possibilities, has seen much progress in the past few years. This allows medical professionals to create bespoke treatment regimens and improve drug adherence through real-time monitoring. TDD also increases the effectiveness of the drugs in much smaller quantities. The use of polymers in the drug delivery field is on the rise owing to their low cost, scalability and ease of manufacture along with drug and bio-compatibility. In this work, we present the design, development and characterization of a polymer-based TDD platform fabricated using additive manufacturing technologies. The system consists of a polymer based micropump integrated with a drug reservoir fabricated by 3D printing and a polymer hollow microneedle array fabricated using photolithography. To the best of our knowledge, we present the fabrication and characterization of a 3D-printed piezoelectrically actuated non-planar valveless micropump and reservoir integrated with a polymer hollow microneedle array for the first time. The integrated system is capable of delivering water at a maximum flow rate of 1.03 mL/min and shows a maximum backpressure of 1.37 kPa while consuming only 400 mW. The system has the least number of moving parts. It can be easily fabricated using additive manufacturing technologies, and it is found to be suitable for drug delivery applications.

Nanomaterials-Functionalized Hydrogels for the Treatment of Cutaneous Wounds

Hydrogels have been utilized extensively in the field of cutaneous wound treatment. The introduction of nanomaterials (NMs), which are a big category of materials with diverse functionalities, can endow the hydrogels with additional and multiple functions to meet the demand for a comprehensive performance in wound dressings. Therefore, NMs-functionalized hydrogels (NMFHs) as wound dressings have drawn intensive attention recently. Herein, an overview of reports about NMFHs for the treatment of cutaneous wounds in the past five years is provided. Firstly, fabrication strategies, which are mainly divided into physical embedding and chemical synthesis of the NMFHs, are summarized and illustrated. Then, functions of the NMFHs brought by the NMs are reviewed, including hemostasis, antimicrobial activity, conductivity, regulation of reactive oxygen species (ROS) level, and stimulus responsiveness (pH responsiveness, photo-responsiveness, and magnetic responsiveness). Finally, current challenges and future perspectives in this field are discussed with the hope of inspiring additional ideas.

Formulation Development and In Vitro/In Vivo Characterization of Methotrexate-Loaded Nanoemulsion Gel Formulations for Enhanced Topical Delivery

Methotrexate-loaded oil-in-water nanoemulsion formulations were prepared using the high shear homogenization technique. A drug excipient study (ATR-FTIR) was carried out to investigate the compatibility between the drug, the polymers, and its admixtures. The thermal stability of the nanoemulsion formulations was evaluated by subjecting them to a heating and cooling cycle. The prepared nanoemulsion formulations (FNE1 to FNE6) were evaluated for particle size, PDI value, and entrapment efficiency (EE). They were analyzed for morphological information using transmission electron microscopy. The drug (methotrexate)-loaded nanoemulsion formulations (FNE2, FNE4, and FNE6) were then converted into nanoemulsion gel formulations by adding 1% chitosan (polymer) as a gelling agent. The nanoemulsion gel formulations (FNEG2, FNEG4, and FNEG6) were investigated for physicochemical parameters, viscosity, spreadability, extrudability, drug content, and skin irritation. Various penetration enhancers (olive oil, clove, and almond oil) were employed to examine the potency of the prepared nanoemulsion gel formulations. In vitro drug release, ex vivo permeation, skin drug retention, and stability tests were carried out for evaluation of the prepared nanoemulsion gel formulations (FNEG2, FNEG4, and FNEG6). The data obtained from the in vitro study were subjected to the kinetic model, and the Korsemeyer-Peppas model was best fitted to the data. The nanoemulsion gel formulation FNEG6 showed the maximum controlled drug release and followed an anomalous, non-Fickian release mechanism. The use of almond oil in the preparation of the nanoemulsion gel formulation FNEG6 helped the penetration of the drug across stratum corneum and the restructuring of the properties of skin and resulted in a higher penetration and retention of methotrexate in a deeper layer of the skin. The current study concluded that the methotrexate-loaded nanoemulsion gel formulation FNEG6 showed the best optimum release, permeation, and retention results as compared to the available oral tablets' formulations, followed by a low serum concentration and the maximum drug retention, which is beneficial in treating skin infections and reducing systemic toxicity.

Bio-Inspired Muco-Adhesive Polymers for Drug Delivery Applications

Muco-adhesive drug delivery systems continue to be one of the most studied for controlled pharmacokinetics and pharmacodynamics. Briefly, muco-adhesive polymers, can be described as bio-polymers that adhere to the mucosal (mucus) surface layer, for an extended residency period of time at the site of application, by the help of interfacial forces resulting in improved drug delivery. When compared to traditional drug delivery systems, muco-adhesive carriers have the potential to enhance therapeutic performance and efficacy, locally and systematically, in oral, rectal, vaginal, amongst other routes. Yet, the achieving successful muco-adhesion in a novel polymeric drug delivery solution is a complex process involving key physico-chemico-mechanical parameters such as adsorption, wettability, polymer chain length, inter-penetration and cross-linking, to list a few. Hence, and in light of accruing progress, evidence and interest, during the last decade, this review aims to provide the reader with an overview of the theories, principles, properties, and underlying mechanisms of muco-adhesive polymers for pharmaceutics; from basics to design to characterization to optimization to evaluation to market. A special focus is devoted to recent advances incorporating bio-inspired polymers for designing controlled muco-adhesive drug delivery systems.

Preparation and in vitro-in vivo evaluation of QbD based acemetacin loaded transdermal patch formulations for rheumatic diseases

This research aimed to develop patches for transdermal delivery of acemetacin, which can be used to treat rheumatic diseasesand to determine their potential use. Patches were successfully created by solvent casting method using hydroxypropyl methylcellulose, propylene glycol, polyethylene glycol 400, tween 80, and dimethyl sulfoxide. Prepared patches were found using the Design of Experiments (DoE) method within the Quality by Design (QbD) approach. F1-ACM with a thickness of 0.1 ± 0.0 cm, a weight of 43.33 ± 6.29 mg, pH of 4.99 ± 0.24, moisture content of 18.33 ± 2.98%, a tensile strength of 9.196 ± 0.441 Mpa, elongation at break of 28.722 ± 0.803% and drug content of 100% was chosen as ideal formulation. 89.7% of ACM from F1-ACM was released in 5 min. F1-ACM significantly (p < 0.05) increased the response latency to the thermal stimulus at 90th (3.071 ± 0.517) and 120th (3.87 ± 0.332) min in the hot plate test. In the tail-flick experiment, F1-ACM significantly (p < 0.05) increased the reaction delay against heat stimuli at 90th (3.016 ± 0.695), 120th (2.884 ± 0.851), and 180th (2.893 ± 0.932) min. F1-ACM patch significantly (p < 0.001) inhibited paw edema formation at 1, 2, 3, 4, and 5 h after induction of inflammation as compared to the control group. Therefore, this formulation can be employed more efficiently for rheumatic disease.

The most promising microneedle device: present and future of hyaluronic acid microneedle patch

Microneedle patch (MNP) is an alternative to the oral route and subcutaneous injection with unique advantages such as painless administration, good compliance, and fewer side effects. Herein, we report MNP as a prominent strategy for drug delivery to treat local or systemic disease. Hyaluronic acid (HA) has advantageous properties, such as human autologous source, strong water absorption, biocompatibility, and viscoelasticity. Therefore, the Hyaluronic acid microneedle patch (HA MNP) occupies a large part of the MNP market. HA MNP is beneficial for wound healing, targeted therapy of certain specific diseases, extraction of interstitial skin fluid (ISF), and preservation of drugs. In this review, we summarize the benefits of HA and cross-linked HA (x-HA) as an MNP matrix. Then, we introduce the types of HA MNP, delivered substances, and drug distribution. Finally, we focus on the biomedical application of HA MNP as an excellent drug carrier in some specific diseases and the extraction and analysis of biomarkers. We also discuss the future development prospect of HA MNP in transdermal drug delivery systems (TDDS).

Mechanistic insights of different release behaviors dominated by drug physicochemical properties in polyisobutylene pressure sensitive adhesive

The purpose of this study was to investigate the effect of the physicochemical parameters of drugs on their own release behaviors in polyisobutylene pressure sensitive adhesive (PIB PSA), which provided a theoretical guidance for the application of PIB in transdermal drug delivery system (TDDS). Seven drugs with different physicochemical parameters including clonidine (CLO), flurbiprofen (FLU), diclofenac (DIC), ibuprofen (IBU), zolmitriptan (ZOL), lidocaine (LID), tulobuterol (TUL) and the mixed adhesive (7:3, w/w) of Oppanol® B 15 N (M.W. = 108,000 Da) and Oppanol® N 50 (M.W. = 565,000 Da) were selected for in vitro drug release and skin permeation studies. Regression analysis was used to study the relationship between physicochemical parameters and release behaviors. The release behaviors of drugs were a negative correlation with polarizability and dipole moment per molecular volume (μ/V), which represented van der Waals and dipole-dipole interaction, respectively. Fourier transform infrared spectroscopy (FT-IR), modulated temperature differential scanning calorimetry (MDSC) and molecular dynamics simulation were used to provide molecular details of the interaction between the drug and PIB. The free volume and molecular mobility of PIB were characterized using mechanical property tests, rheology study, MDSC and molecular dynamics simulation. Based on the above results, drugs with high polarizability and μ/V had stronger van der Waals and dipole-dipole interaction with PIB, reducing the free volume and molecular mobility of PIB, so that the drug struggled to release from PIB. In addition, the diffusion activation energy of the drug was calculated by using the variable temperature release study to characterize the ease of drug release from the kinetic aspect. And the trends of in vitro drug release and skin penetration profiles were basically similar. Thus, it was thought that the physicochemical parameters of the drug played a vital role in the drug release behavior of PIB PSAs and would affect the skin penetration process, which provided a reference for the design and application of patches based on PIB PSAs in TDDS.

Natural polysaccharide-based biodegradable polymeric platforms for transdermal drug delivery system: a critical analysis

Natural biodegradable polymers generally include polysaccharides (starch, alginate, chitin/chitosan, hyaluronic acid derivatives, etc.) and proteins (collagen, gelatin, fibrin, etc.). In transdermal drug delivery systems (TDDS), these polymers play a vital role in controlling the device's drug release. It is possible that natural polymers can be used for TDDS to attain predetermined drug delivery rates due to their physicochemical properties. These polymers can be employed to market products and scale production because they are readily available and inexpensive. As a result of these polymers, new pharmaceutical delivery systems can be developed that is both regulated and targeted. The focus of this article is the application of a biodegradable polymeric platform based on natural polymers for TDDS. Due to their biocompatibility and biodegradability, natural biodegradable polymers are frequently used in biomedical applications. Additionally, these natural biodegradable polymers are being studied for their characteristics and behaviors.

Precise Design Strategies of Nanotechnologies for Controlled Drug Delivery

Rapid advances in nanotechnologies are driving the revolution in controlled drug delivery. However, heterogeneous barriers, such as blood circulation and cellular barriers, prevent the drug from reaching the cellular target in complex physiologic environments. In this review, we discuss the precise design of nanotechnologies to enhance the efficacy, quality, and durability of drug delivery. For drug delivery in vivo, drugs loaded in nanoplatforms target particular sites in a spatial- and temporal-dependent manner. Advances in stimuli-responsive nanoparticles and carbon-based drug delivery platforms are summarized. For transdermal drug delivery systems, specific strategies including microneedles and hydrogel lead to a sustained release efficacy. Moreover, we highlight the current limitations of clinical translation and an incentive for the future development of nanotechnology-based drug delivery.

Development of Clinical Weekly-Dose Teriparatide Acetate Encapsulated Dissolving Microneedle Patch for Efficient Treatment of Osteoporosis

Teriparatide acetate (TA), which directly promotes bone formation, is subcutaneously injected to treat osteoporosis. In this study, TA with a once-weekly administration regimen was loaded on dissolving microneedles (DMNs) to effectively deliver it to the systemic circulation via the transdermal route. TA activity reduction during the drying process of various TA polymer solutions formulated with hyaluronic acid and trehalose was monitored and homogeneities were assessed. TA-DMN patches fabricated using centrifugal lithography in a two-layered structure with dried pure hyaluronic acid on the base layer and dried TA polymer solution on the top layer were evaluated for their physical properties. Rhodamine-B-loaded TA-DMNs were found to form perforations when inserted into porcine skin using a shooting device. In addition, 87.6% of TA was delivered to the porcine skin after a 5-min TA-DMN patch application. The relative bioavailability of TA via subcutaneous injection was 66.9% in rats treated with TA-DMN patches. The maximal TA concentration in rat plasma was proportional to the number of patches used. Therefore, the TA-DMN patch fabricated in this study may aid in the effective delivery of TA in a patient-friendly manner and enhance medical efficacy in osteoporosis treatment.

Overcoming skin barriers through advanced transdermal drug delivery approaches

Upon exhaustive research, the transdermal drug delivery system (TDDS) has appeared as a potential, well-accepted, and popular approach to a novel drug delivery system. Ease of administration, easy handling, minimum systemic exposure, least discomfort, broad flexibility and tunability, controlled release, prolonged therapeutic effect, and many more perks make it a promising approach for effective drug delivery. Although, the primary challenge associated is poor skin permeability. Skin is an intact barrier that serves as a primary defense mechanism to preclude any foreign particle's entry into the body. Owing to the unique anatomical framework, i.e., compact packing of stratum corneum with tight junction and fast anti-inflammatory responses, etc., emerged as a critical physiological barrier for TDDS. Fusion with other novel approaches like nanocarriers, specially designed transdermal delivery devices, permeation enhancers, etc., can overcome the limitations. Utilizing such strategies, some of the products are under clinical trials, and many are under investigation. This review explores all dimensions that overcome poor permeability and allows the drug to attain maximum potential. The article initially compiles fundamental features, components, and design of TDDS, followed by critical aspects and various methods, including in vitro, ex vivo, and in vivo methods of assessing skin permeability. The work primarily aimed to highlight the recent advancement in novel strategies for effective transdermal drug delivery utilizing active methods like iontophoresis, electroporation, sonophoresis, microneedle, needleless jet injection, etc., and passive methods such as the use of liposomes, SLN, NLC, micro/nanoemulsions, dendrimers, transferosomes, and many more nanocarriers. In all, this compilation will provide a recent insight on the novel updates along with basic concepts, the current status of clinical development, and challenges for the clinical translation of TDDS.

Development of a Silicone-Based Polymer Matrix as a Suitable Transdermal Therapeutic System for Diallyl Disulfide

There is an unmet need for novel therapeutic tools relieving chronic pain. Hydrogen sulfide (H₂S) is highly involved in pain processes; however, the development of ideal matrices for sulfide donor compounds remains a great pharmaceutical challenge. We aimed to establish a suitable transdermal therapeutic system (TTS) using the H₂S donor diallyl disulfide (DADS) as a model compound. After the preparation of DADS, its solubility was investigated in different liquid excipients (propylene glycol, polyethylene glycol, silicone oil) and its membrane diffusivity was assessed in silicone matrices of different compositions. Drug-releasing properties of DADS-containing patches with different silicone oil contents were determined with Franz and flow-through cells. We found a correlation between the liquid excipient content of the patch and the diffusion rate of DADS. DADS showed the best solubility in dimethyl silicone oil, and the diffusion constant was proportional to the amount of oil above the 3 m/m% threshold value. The 8-day-old patch showed a significantly lower, but better-regulated, drug release over time than the 4-day-old one. In conclusion, the silicone-based polymer matrix developed in this study is suitable for stable storage and optimal release of DADS, providing a good basis for a TTS applied in chronic pain.

Drug in adhesive transdermal patch containing antibiotic-loaded solid lipid nanoparticles

The structure of the skin only allows those hydrophobic elements to penetrate through the depth of the skin with low molecular weight (less than 500 Da) and low daily dose (less than 100 mg/day). Skin penetration of many drugs such as antibiotics at a high daily dose remains an unresolved challenge. In this study a transdermal patch using cephalexin as an antibiotic drug model was developed. Cephalexin was loaded into α-tocopherol succinate-based solid lipid nanoparticles (SLNs). Cephalexin-loaded SLNs with a drug/lipid ratio of 20%, diameter of 180 ± 7 nm, and drug loading 7.9% led to the greatest inhibition zone of Staphylococcus aureus and showed the highest skin permeation capabilities. Cephalexin-loaded SLNs were distributed into poly-iso-butylene adhesive solution and final patches prepared using solvent casting. The physico-chemical characteristics, in vitro drug release, antimicrobial efficacy, and skin cell proliferation properties of patches were evaluated. Results indicated that the optimal transdermal patch formulation containing 90% adhesive solution, 7% cephalexin, and 3% cephalexin-loaded SLNs (with antibiotic content approximately 28% less) inhibited growth of S.aureus better than the formulation containing 90% adhesive solution and 10% cephalexin. In vitro evaluation of the growth of human fibroblast skin cells in media with the optimal patch exhibited greater proliferation (about 25.5%) than those in media without the patch.

Drug Delivery System Based on Carboxymethyl Cellulose Containing Metal-Organic Framework and Its Evaluation for Antibacterial Activity

A novel drug delivery system based on carboxymethyl cellulose containing copper oxide at melamine and zinc oxide at melamine framework (CMC-Cu-MEL and CMC-Zn-MEL) was prepared by the hydrothermal route. Synthesized nanocomposites were characterized by FTIR, SEM, and Raman spectroscopy. In addition, transmission electron microscopy (TEM) and selected area electron diffraction (SAED) images were applied to confirm the particle size and diffraction pattern of the prepared nanocomposites. Furthermore, the crystallinity of the synthesized CMC, CMC-Cu-MEL, and CMC-Zn-MEL materials was studied via X-ray diffraction (XRD). Estimating the transport exponent, which discloses the solvent diffusion and chain relaxation processes, and the Ritger–Peppas kinetic model theory were used to control the TC release mechanism from CMC-Cu-MEL and CMC-Zn-MEL. Additionally, the CMC-Cu-MEL and CMC-Zn-MEL containing TC had the highest activity index percents of 99 and 106% against S. aureus and 93 and 99% against E. coli, respectively. The tailored CMC-Cu-MEL and CMC-Zn-MEL for drug delivery systems are expected to be feasible and efficient.

Fe(III)-coordinated N-[tris(hydroxymethyl)methyl]acrylamide-modified acrylic pressure-sensitive adhesives with enhanced adhesion and cohesion for efficient transdermal application

Pressure-sensitive adhesives are critical to the product's safety, efficacy, and quality in transdermal drug delivery systems. However, many defects of transdermal patches (e.g., insufficient adhesion, patch displacement, and "dark ring" phenomenon) remain. Herein, the N-[tris(hydroxymethyl)methyl]acrylamide (NAT)-modified acrylic pressure-sensitive adhesive coordinated with Fe(III) (AA-NAT/Fe³⁺) was creatively proposed. Results demonstrated that the adhesiveness and cohesiveness of the optimized AA-NAT/Fe³⁺ were higher by 1.8- and 9.7-fold, respectively, than those of commercially available DURO-TAK® 87-4098 due to the hydrogen bonding interaction of NAT-skin interface and coordination of NAT-Fe³⁺. Moreover, compared with that of DURO-TAK® 87-4098, the adhesion time of AA-NAT/Fe³⁺ on the human forearm was remarkably prolonged, and no "dark ring" phenomenon was observed for AA-NAT/Fe³⁺ after removal. After clonidine (CLO) was loaded into AA-NAT/Fe³⁺, controlled drug release and a drug transdermal behavior were endowed for CLO@AA-NAT/Fe³⁺in vitro and in vivo. AA-NAT/Fe³⁺ still maintained superiority in adhesion and cohesion properties after CLO loading. These observations would contribute to the development of pressure-sensitive adhesives with outstanding adhesion and cohesion for transdermal patches. STATEMENT OF SIGNIFICANCE: This N-[tris(hydroxymethyl)methyl]acrylamide-modified acrylic pressure-sensitive adhesive coordinated with Fe(III) has enhanced adhesion and cohesion properties, which provide a simple but effective strategy to solve the problems (e.g., insufficient adhesion, patch displacement, and "dark ring" phenomenon) in existing transdermal patches.

Microneedle Patch Delivery of Methotrexate-Loaded Albumin Nanoparticles to Immune Cells Achieves a Potent Antipsoriatic Effect

Introduction

Transdermal drug delivery provides a desirable alternative method of penetrating the skin for psoriasis treatment, by virtue of its ability to dampen the overactivation of immune cells and inflammation, while attenuating the detrimental effects of systemic administration. Lymph nodes (LNs), as a critical organ of the lymphatic and the acquired immune system, are suitable sites for drug homing to suppress the immune cells.

Methods

In this context, we developed a microneedle (MN) patch that delivers nanodrugs locally to LNs for improving the antipsoriatic treatment. In this study, human serum albumin nanoparticles carrying methotrexate (HM) were synthesized and loaded into hyaluronic acid (HA)-based microneedles (HM/MN).

Results

The patch showed an excellent ability to pierce the skin, which enhanced drug delivery. In a mouse model of psoriasis, the HM/MN patch significantly prevented the erythema with decreased skin thickness, thus inhibiting the progression of psoriasis. Further analysis for immune cells in LNs, the percent of dendritic cells (DC) and T cells reduced after the local treatment with HM/MN. Notably, the feasibility of targeted delivery of methotrexate to LNs using nanoparticles was verified by detecting increased accumulation of methotrexate in LNs. In addition, the HM/MN patch pronouncedly decreased the levels of tumor necrosis factor α and interleukin 6 in the skin.

Conclusion

The results suggested the high efficacy of using the HM/MN patch to treat psoriasis, and provided new insight into the mechanism of the transdermal drug delivery system.

Biopolymer Nanoparticles for Nose-to-Brain Drug Delivery: A New Promising Approach for the Treatment of Neurological Diseases

Diseases affecting the central nervous system (CNS) are among the most disabling and the most difficult to cure due to the presence of the blood–brain barrier (BBB) which represents an impediment from a therapeutic and diagnostic point of view as it limits the entry of most drugs. The use of biocompatible polymer nanoparticles (NPs) as vehicles for targeted drug delivery to the brain arouses increasing interest. However, the route of administration of these vectors remains critical as the drug must be delivered without being degraded to achieve a therapeutic effect. An innovative approach for the administration of drugs to the brain using polymeric carriers is represented by the nose-to-brain (NtB) route which involves the administration of the therapeutic molecule through the neuro-olfactory epithelium of the nasal mucosa. Nasal administration is a non-invasive approach that allows the rapid transport of the drug directly to the brain and minimizes its systemic exposure. To date, many studies involve the use of polymer NPs for the NtB transport of drugs to the brain for the treatment of a whole series of disabling neurological diseases for which, as of today, there is no cure. In this review, various types of biodegradable polymer NPs for drug delivery to the brain through the NtB route are discussed and particular attention is devoted to the treatment of neurological diseases such as Glioblastoma and neurodegenerative diseases.

Applications of Electrospun Drug-Eluting Nanofibers in Wound Healing: Current and Future Perspectives

Wounds are a consequence of disruption in the structure, integrity, or function of the skin or tissue. Once a wound is formed following mechanical or chemical damage, the process of wound healing is initiated, which involves a series of chemical signaling and cellular mechanisms that lead to regeneration and/or repair. Disruption in the healing process may result in complications; therefore, interventions to accelerate wound healing are essential. In addition to mechanical support provided by sutures and traditional wound dressings, therapeutic agents play a major role in accelerating wound healing. The medicines known to improve the rate and extent of wound healing include antibacterial, anti-inflammatory, and proliferation enhancing agents. Nonetheless, the development of these agents into eluting nanofibers presents the possibility of fabricating wound dressings and sutures that provide mechanical support with the added advantage of local delivery of therapeutic agents to the site of injury. Herein, the process of wound healing, complications of wound healing, and current practices in wound healing acceleration are highlighted. Furthermore, the potential role of drug-eluting nanofibers in wound management is discussed, and lastly, the economic implications of wounds as well as future perspectives in applying fiber electrospinning in the design of wound dressings and sutures are considered and reported.

Lasered Graphene Microheaters Modified with Phase-Change Composites: New Approach to Smart Patch Drug Delivery

The combination of paraffin wax and O,O′-bis(2-aminopropyl) polypropylene glycol–block–polyethylene glycol–block–polypropylene glycol was used as a phase-change material (PCM) for the controlled delivery of curcumin. The PCM was combined with a graphene-based heater derived from the laser scribing of polyimide film. This assembly provides a new approach to a smart patch through which release can be electronically controlled, allowing repetitive dosing. Rather than relying on passive diffusion, delivery is induced and terminated through the controlled heating of the PCM with transfer only occurring when the PCM transitions from solid to liquid. The material properties of the device and release characteristics of the strategy under repetitive dosing are critically assessed. The delivery yield of curcumin was found to be 3.5 µg (4.5 µg/cm²) per 3 min thermal cycle.

Combined Strategy of Wound Healing Using Thermo-Sensitive PNIPAAm Hydrogel and CS/PVA Membranes: Development and In-Vivo Evaluation

Past studies have shown that the hot spring effect can promote wound healing. Mild thermal stimulation and metal ions can promote angiogenesis. In this study, the hot spring effect was simulated by thermosensitive PNIPAAm hydrogel loaded with copper sulfide nanoparticles. Heat stimulation could be generated through near-infrared irradiation, and copper ions solution could be pulsed. On the other hand, the CS/PVA nanofiber membrane was attached to the bottom of the hydrogel to simulate the extracellular matrix structure, thus improving the wound healing ability. The CS/PVA nanofiber membrane was prepared by electrospinning, and the appropriate prescription and process parameters were determined. The nanofiber membrane has uniform pore size, good water absorption and permeability. The poor mechanical properties of PNIPAAm hydrogel were improved by adding inorganic clay. The temperature of the hydrogel loaded with CuS nanoparticles reached 40 °C under near-infrared light irradiation for 20 min, and the release rate of Cu²⁺ reached 26.89%. The wound-healing rate of the rats in the combined application group reached 79.17% at 13 days, demonstrating superior results over the other control groups. Histological analyses show improved inflammatory response at the healed wound area. These results indicate that this combined application approach represents a promising wound treatment strategy.

Role and Function of Mesenchymal Stem Cells on Fibroblast in Cutaneous Wound Healing

Skin wounds often repair themselves completely over time; however, this is true only for healthy individuals. Although various studies are being conducted to improve wound-healing therapy outcomes, the mechanisms of wound healing and regeneration are not completely understood yet. In recent years, mesenchymal stem cells (MSCs) have been reported to contribute significantly to wound healing and regeneration. Understanding the function of MSCs will help to elucidate the fundamentals of wound healing. MSCs are multipotent stem cells that are used in regenerative medicine for their ability to self-renew and differentiate into bone, fat, and cartilage, with few ethical problems associated with cell harvesting. Additionally, they have anti-inflammatory and immunomodulatory properties and antifibrotic effects via paracrine signaling, and many studies have been conducted to use them to treat graft-versus-host disease, inflammatory bowel disease, and intractable cutaneous wounds. Many substances derived from MSCs are involved in the wound-healing process, and specific cascades and pathways have been elucidated. This review aims to explain the fundamental role of MSCs in wound healing and the effects of MSCs on fibroblasts.

Novel Retro-Inverso Peptide Antibiotic Efficiently Released by a Responsive Hydrogel-Based System

Topical antimicrobial treatments are often ineffective on recalcitrant and resistant skin infections. This necessitates the design of antimicrobials that are less susceptible to resistance mechanisms, as well as the development of appropriate delivery systems. These two issues represent a great challenge for researchers in pharmaceutical and drug discovery fields. Here, we defined the therapeutic properties of a novel peptidomimetic inspired by an antimicrobial sequence encrypted in human apolipoprotein B. The peptidomimetic was found to exhibit antimicrobial and anti-biofilm properties at concentration values ranging from 2.5 to 20 µmol L⁻¹, to be biocompatible toward human skin cell lines, and to protect human keratinocytes from bacterial infections being able to induce a reduction of bacterial units by two or even four orders of magnitude with respect to untreated samples. Based on these promising results, a hyaluronic-acid-based hydrogel was devised to encapsulate and to specifically deliver the selected antimicrobial agent to the site of infection. The developed hydrogel-based system represents a promising, effective therapeutic option by combining the mechanical properties of the hyaluronic acid polymer with the anti-infective activity of the antimicrobial peptidomimetic, thus opening novel perspectives in the treatment of skin infections.

Formulation of Polymers-Based Methotrexate Patches and Investigation of the Effect of Various Penetration Enhancers: In Vitro, Ex Vivo and In Vivo Characterization

The present study aimed to prepare methotrexate-loaded transdermal patches with different blends of hydrophobic and hydrophilic polymers (Eudragit S-100 and hydroxypropyl methylcellulose) at different concentrations. The polymers employed in transdermal patches formulations served as controlled agent. Transdermal patches were prepared using the solvent casting technique. The suitable physicochemical properties were obtained from the formulation F5 (HPMC and Eudragit S-100 (5:1). Various penetration enhancers were employed in different concentrations to investigate their potential for enhancing the drug permeation profile from optimized formulations. A preformulation study was conducted to investigate drug-excipient compatibilities (ATR-FTIR) and the study showed greater compatibility between drug, polymers and excipients. The prepared patches containing different penetration enhancers at different concentrations were subjected for evaluating different physicochemical parameters and in vitro drug release studies. The obtained data were added to various kinetic models, then formulated patch formulations were investigated for ex vivo permeation studies, in vivo studies and skin drug retention studies. The prepared patches showed elastic, smooth and clear nature with good thickness, drug content, % moisture uptake and weight uniformity. The prepared transdermal patches showed % drug content ranging from 91.43 ± 2.90 to 98.37 ± 0.56, % swelling index from 36.98 ± 0.19 to 75.32 ± 1.21, folding endurance from 61 ± 3.14 to 78 ± 1.54 and tensile strength from 8.54 ± 0.18 to 12.87 ± 0.50. The formulation F5, containing a greater amount of hydrophilic polymers (HPMC), showed increased drug release and permeation and drug retention when compared to other formulated transdermal patch formulations (F1-F9). No significant change was observed during a stability study for a period of 60 days. The rabbit skin samples were subjected to ATR-FTIR studies, which revealed that polymers and penetration enhancers have affected skin proteins (ceramides and keratins). The pharmacokinetic profiling of optimized formulation (F5) as well as formulations with optimized concentrations of penetration enhancers revealed C_max ranged 167.80 ng/mL to 178.07 ± 2.75 ng/mL, T_max was 8 h to 10 h, and t^1/2 was 15.9 ± 2.11 to 21.49 ± 1.16. From the in vivo studies, it was revealed that the formulation F5-OA-10% exhibited greater skin drug retention as compared to other formulations. These results depicted that prepared methotrexate transdermal patches containing different blends of hydrophobic and hydrophilic polymers along with different penetration enhancers could be safely used for the management of psoriasis. The formulated transdermal patches exhibited sustained release of drug with good permeations and retention profile. Hence, these formulated transdermal patches can effectively be used for the management of psoriasis.

Simultaneous Release of Silver Ions and 10–Undecenoic Acid from Silver Iron–Oxide Nanoparticles Impregnated Membranes

The bio-medical benefits of silver ions and 10–undecenoic acid in various chemical-pharmaceutical preparations are indisputable, thus justifying numerous research studies on delayed and/or controlled release. This paper presents the effect of the polymer matrix in the simultaneous release of silver ions and 10–undecenoic acid in an aqueous medium of controlled pH and ionic strength. The study took into consideration polymeric matrices consisting of cellulose acetate (CA) and polysulfone (PSf), which were impregnated with oxide nanoparticles containing silver and 10–undecenoic acid. The studied oxide nanoparticles are nanoparticles of iron and silver oxides obtained by an accessible electrochemical method. The obtained results show that silver can be released, simultaneously with 10–undecenoic acid, from an impregnated polymeric membrane, at concentrations that ensure the biocidal and fungicidal capacity. Concentrations of active substances can be controlled by choosing the polymer matrix or, in some cases, by changing the pH of the target medium. In the studied case, higher concentrations of silver ions are released from the polysulfone matrix, while higher concentrations of 10–undecenoic acid are released from the cellulose acetate matrix. The results of the study show that a correlation can be established between the two released target substances, which is dependent on the solubility of the organic compound in the aqueous medium and the interaction of this compound with the silver ions. The ability of 10–undecenoic acid to interact with the silver ion, both through the carboxyl and alkene groups, contributes to the increase in the content of the silver ions transported in the aqueous medium.

Dendrobium officinale Enzyme Changing the Structure and Behaviors of Chitosan/γ-poly(glutamic acid) Hydrogel for Potential Skin Care

Hydrogels have been widespreadly used in various fields. But weak toughness has limited their further applications. In this study, Dendrobium officinale enzyme (DOE) was explored to improve chitosan/γ-poly(glutamic acid) (CS/γ-PGA) hydrogel in the structure and properties. The results indicated that DOE with various sizes of ingredients can make multiple noncovalent crosslinks with the skeleton network of CS/γ-PGA, significantly changing the self-assembly of CS/γ-PGA/DOE hydrogel to form regular protuberance nanostructures, which exhibits stronger toughness and better behaviors for skin care. Particularly, 4% DOE enhanced the toughness of CS/γ-PGA/DOE hydrogel, increasing it by 116%. Meanwhile, water absorption, antioxygenation, antibacterial behavior and air permeability were increased by 39%, 97%, 27% and 52%.

Gut–Skin Axis: Unravelling the Connection between the Gut Microbiome and Psoriasis

Evidence has shown that gut microbiome plays a role in modulating the development of diseases beyond the gastrointestinal tract, including skin disorders such as psoriasis. The gut–skin axis refers to the bidirectional relationship between the gut microbiome and skin health. This is regulated through several mechanisms such as inflammatory mediators and the immune system. Dysregulation of microbiota has been seen in numerous inflammatory skin conditions such as atopic dermatitis, rosacea, and psoriasis. Understanding how gut microbiome are involved in regulating skin health may lead to development of novel therapies for these skin disorders through microbiome modulation, in particularly psoriasis. In this review, we will compare the microbiota between psoriasis patients and healthy control, explain the concept of gut–skin axis and the effects of gut dysbiosis on skin physiology. We will also review the current evidence on modulating gut microbiome using probiotics in psoriasis.

One-Step Synthesis of Cross-Linked Esterified Starch and Its Properties

Cross-linked esterified starch (CES) was prepared using a one-step method, where maize starch was selected as the raw material, sodium trimetaphosphate as the cross-linking agent, and acetic anhydride as the esterifying agent, respectively. A response surface experiment was systematically conducted for analyzing the correlation of the experimental variables (cross-linked temperature, pH, reaction time, sodium trimetaphosphate and acetic anhydride dosage) and properties of the product (peak and final viscosity). The Brabender viscosity, freeze-thaw stability, shearing resistance, and acid tolerance of the cross-linked acetylated dual modified starch were studied under different conditions of crosslinking degree and acetyl content. Meanwhile, the granular structure and morphology of the modified starch were analyzed. The results indicated that: after cross-linked acetylated dual modification, the starch had a distinct birefringence and granular structure, along with the creation of new carbonyl groups. The low degree of crosslinking and high acetyl contents were beneficial to the viscosity, which was significantly increased at both low and high temperatures. Moreover, the freeze-thaw stability of CES was elevated sharply after five cycles. In addition, CES displayed increased shear and acid tolerance compared to the original waxy maize, and their lowest differences between waxy maize and CES were only 0.62% and 0.59%, respectively. In summary, a novel method for starch modification was provided, and the synthesized CES was suggested to have exceptional performance for the food industry.

Mechanism and Application of Chitosan and Its Derivatives in Promoting Permeation in Transdermal Drug Delivery Systems: A Review

The mechanisms and applications of chitosan and its derivatives in transdermal drug delivery to promote drug permeation were reviewed in this paper. Specifically, we summarized the permeation-promoting mechanisms of chitosan and several of its derivatives, including changing the structure of stratum corneum proteins, acting on the tight junction of granular layers, affecting intercellular lipids, and increasing the water content of stratum corneum. These mechanisms are the reason why chitosan and its derivatives can increase the transdermal permeation of drugs. In addition, various transdermal preparations containing chitosan and its derivatives were summarized, and their respective advantages were expounded, including nanoparticles, emulsions, transdermal microneedles, nanocapsules, transdermal patches, transdermal membranes, hydrogels, liposomes, and nano-stents. The purpose of this review is to provide a theoretical basis for the further and wider application of chitosan in transdermal drug delivery systems. In the future, research results of chitosan and its derivatives in transdermal drug delivery need more support from in vivo experiments, as well as good correlation between in vitro and in vivo experiments. In conclusion, the excellent permeability-promoting property, good biocompatibility, and biodegradability of chitosan and its derivatives make them ideal materials for local transdermal drug delivery.

Molecularly Imprinted Polymers as State-of-the-Art Drug Carriers in Hydrogel Transdermal Drug Delivery Applications

Molecularly Imprinted Polymers (MIPs) are polymeric networks capable of recognizing determined analytes. Among other methods, non-covalent imprinting has become the most popular synthesis strategy for Molecular Imprinting Technology (MIT). While MIPs are widely used in various scientific fields, one of their most challenging applications lies within pharmaceutical chemistry, namely in therapeutics or various medical therapies. Many studies focus on using hydrogel MIPs in transdermal drug delivery, as the most valuable feature of hydrogels in their application in drug delivery systems that allow controlled diffusion and amplification of the microscopic events. Hydrogels have many advantages over other imprinting materials, such as milder synthesis conditions at lower temperatures or the increase in the availability of biological templates like DNA, protein, and nucleic acid. Moreover, one of the most desirable controlled drug delivery applications is the development of stimuli-responsive hydrogels that can modulate the release in response to changes in pH, temperature, ionic strength, or others. The most important feature of these systems is that they can be designed to operate within a particular human body area due to the possibility of adapting to well-known environmental conditions. Therefore, molecularly imprinted hydrogels play an important role in the development of modern drug delivery systems.

Spaceflight Stressors and Skin Health

Traveling to space puts astronauts at risk of developing serious health problems. Of particular interest is the skin, which is vitally important in protecting the body from harmful environmental factors. Although data obtained from long-duration spaceflight studies are inconsistent, there have been indications of increased skin sensitivity and signs of dermal atrophy in astronauts. To better understand the effects of spaceflight stressors including microgravity, ionizing radiation and psychological stress on the skin, researchers have turned to in vitro and in vivo simulation models mimicking certain aspects of the spaceflight environment. In this review, we provide an overview of these simulation models and highlight studies that have improved our understanding on the effect of simulation spaceflight stressors on skin function. Data show that all aforementioned spaceflight stressors can affect skin health. Nevertheless, there remains a knowledge gap regarding how different spaceflight stressors in combination may interact and affect skin health. In future, efforts should be made to better simulate the spaceflight environment and reduce uncertainties related to long-duration spaceflight health effects.

Recent progress in polymeric non-invasive insulin delivery

The design of carriers for insulin delivery has recently attracted major research attentions in the biomedical field. In general, the release of drug from polymers is driven via a variety of polymers. Several mechanisms such as matrix release, leaching of drug, swelling, and diffusion are usually adopted for the release of drug through polymers. Insulin is one of the most predominant therapeutic drugs for the treatment of both diabetes mellitus; type-I (insulin-dependent) and type II (insulin-independent). Currently, insulin is administered subcutaneously, which makes the patient feel discomfort, pain, hyperinsulinemia, allergic responses, lipodystrophy surrounding the injection area, and occurrence of miscarried glycemic control. Therefore, significant research interest has been focused on designing and developing new insulin delivery technologies to control blood glucose levels and time, which can enhance the patient compliance simultaneously through alternative routes as non-invasive insulin delivery. The aim of this review is to emphasize various non-invasive insulin delivery mechanisms including oral, transdermal, rectal, vaginal, ocular, and nasal. In addition, this review highlights different smart stimuli-responsive insulin delivery systems including glucose, pH, enzymes, near-infrared, ultrasound, magnetic and electric fields, and the application of various polymers as insulin carriers. Finally, the advantages, limitations, and the effect of each non-invasive route on insulin delivery are discussed in detail.