Ultrasound mediated transdermal drug delivery

Microneedles as a Promising Technology for Disease Monitoring and Drug Delivery: A Review

The delivery of molecules, such as DNA, RNA, peptides, and certain hydrophilic drugs, across the epidermal barrier poses a significant obstacle. Microneedle technology has emerged as a prominent area of focus in biomedical research because of its ability to deliver a wide range of biomolecules, vaccines, medicines, and other substances through the skin. Microneedles (MNs) form microchannels by disrupting the skin's structure, which compromises its barrier function, and facilitating the easy penetration of drugs into the skin. These devices enhance the administration of many therapeutic substances to the skin, enhancing their stability. Transcutaneous delivery of medications using a microneedle patch offers advantages over conventional drug administration methods. Microneedles containing active substances can be stimulated by different internal and external factors to result in the regulated release of the substances. To achieve efficient drug administration to the desired location, it is necessary to consider the design of needles with appropriate optimized characteristics. The choice of materials for developing and manufacturing these devices is vital in determining the pharmacodynamics and pharmacokinetics of drug delivery. This article provides the most recent update and overview of the numerous microneedle systems that utilize different activators to stimulate the release of active components from the microneedles. Further, it discusses the materials utilized for producing microneedles and the design strategies important in managing the release of drugs. An explanation of the commonly employed fabrication techniques in biomedical applications and electronics, particularly for integrated microneedle drug delivery systems, is discussed. To successfully implement microneedle technology in clinical settings, it is essential to comprehensively assess several factors, such as biocompatibility, drug stability, safety, and production cost. Finally, an in-depth review of these criteria and the difficulties and potential future direction of microneedles in delivering drugs and monitoring diseases is explored.

Natural Epithelial Barrier Integrity Enhancers-Citrus medica and Origanum dayi Extracts

Buccal drug delivery offers a promising alternative for avoiding gastrointestinal degradation and first-pass metabolism. However, enhancing the buccal epithelial barrier's permeability remains challenging. This study explores the effects of ethanolic extracts from Citrus medica var. Balady (CM), Citrus medica var. Calabria (CMC), and Origanum dayi (ORD) on buccal epithelium permeability in vitro using a TR146 cell-based model. The cell viability assay revealed that the extracts were non-toxic at the concentration range tested (<0.5% w/v). Surprisingly, none of the tested extracts significantly enhanced the buccal permeability of 40 kDa Fluorescein Isothiocyanate Dextran (FD40). However, the CMC and ORD extracts significantly reduced the epithelial permeability of FD40, mirroring the effects of hyaluronic acid (HA), a known barrier integrity enhancer. The total phenolic content (TPC) analysis suggested a potential link between the phenolic concentration and epithelial barrier reinforcement. The rapid colorimetric response method was applied to assess the interaction of these extracts with biological membranes. The results indicated that HA interacts with cellular membranes via lipid bilayer penetration, whereas the extracts likely influence the barrier integrity through alternative mechanisms, such as ligand-receptor interactions or extracellular matrix modulation. These findings highlight the potential of CMC and ORD extracts as natural agents to enhance buccal epithelial integrity. In conclusion, incorporating these extracts into formulations, such as hydrogels, could offer a cost-effective and biocompatible alternative to HA for improving buccal cavity health.

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.

Niacinamide: a review on dermal delivery strategies and clinical evidence

Niacinamide, an active form of vitamin B3, is recognised for its significant dermal benefits including skin brightening, anti-ageing properties and the protection of the skin barrier. Its widespread incorporation into cosmetic products, ranging from cleansers to serums, is attributed to its safety profile and proven efficacy. Recently, topical niacinamide has also been explored for other pharmaceutical applications, including skin cancers. Therefore, a fundamental understanding of the skin permeation behaviour of niacinamide becomes crucial for formulation design. Given the paucity of a comprehensive review on this aspect, we provide insights into the mechanisms of action of topically applied niacinamide and share the current strategies used to enhance its skin permeation. This review also consolidates clinical evidence of topical niacinamide for its cosmeceutical uses and as treatment for some skin disorders, including dermatitis, acne vulgaris and actinic keratosis. We also emphasise the current exploration and perspectives on the delivery designs of topical niacinamide, highlighting the potential development of formulations focused on enhancing skin permeation, particularly for clinical benefits.

Comparative study of permeation effects between vibrating microneedle and low-frequency sonophoresis systems

Microneedle transdermal administration and low-frequency ultrasound represent two important physical penetration-promoting methods for enhancing drug penetration. This article aims to investigate and compare the effects of drug penetration enhancement through transdermal administration using vibrating microneedles versus low-frequency sonophoresis. In Vitro permeation studies were conducted using Valia-Chien double chamber diffusion cells to evaluate the transdermal delivery of tetramethylpyrazine hydrochloride (TMPH). The TMPH concentration in the receiving compartment was determined using high-performance liquid chromatography (HPLC). Several combinations of microneedles and ultrasound settings were investigated, including different needle heights, vibration frequencies, exposure times, and assorted distances of ultrasound horn and skin. The results revealed the vibrating microneedle system as the most efficacious treatment to increase the TMPH permeability into the rat skin. The combination of a larger needle, higher frequency, and a 3-min exposure led to a 41.92-fold increase in cumulative permeability compared to the control group. The ultrasound treatment exhibited a moderate enhancement effect on TMPH skin penetration. Using a horn-to-skin distance of 3 mm and a 3-min exposure resulted in a 4.34-fold increase in TMPH cumulative permeation compared to the control group. It could be concluded that while both the vibrating microneedle and the low-frequency ultrasound systems act as penetration enhancers for promoting the TMPH permeation through the skin, the vibrating microneedle system notably demonstrates a more effective penetration-promoting effect.

Design Principles and Applications of Ionic Liquids for Transdermal Drug Delivery

Ionic liquids (ILs) are salts with melting points typically <100 °C, composed of specific anions and cations. Recently, IL application has expanded into material engineering and biomedicine. Due to their unique properties, ILs have garnered significant interest in pharmacological research as solubilizers, transdermal absorption enhancers, antibacterial agents, and stabilizers of insoluble pharmaceutical active ingredients. The improvement of skin permeability by ILs is closely associated with their specific physicochemical characteristics, which are identified by their ionic composition. However, the existing literature on transdermal medication administration is insufficient in terms of a comprehensive knowledge base. This review provides a comprehensive assessment of the design principles involved in IL synthesis. Additionally, it discusses the methods utilized to assess skin permeability and provides a focused outline of IL application in transdermal drug administration.

The Design Features, Quality by Design Approach, Characterization, Therapeutic Applications, and Clinical Considerations of Transdermal Drug Delivery Systems-A Comprehensive Review

Transdermal drug delivery systems (TDDSs) are designed to administer a consistent and effective dose of an active pharmaceutical ingredient (API) through the patient's skin. These pharmaceutical preparations are self-contained, discrete dosage forms designed to be placed topically on intact skin to release the active component at a controlled rate by penetrating the skin barriers. The API provides the continuous and prolonged administration of a substance at a consistent rate. TDDSs, or transdermal drug delivery systems, have gained significant attention as a non-invasive method of administering APIs to vulnerable patient populations, such as pediatric and geriatric patients. This approach is considered easy to administer and helps overcome the bioavailability issues associated with conventional drug delivery, which can be hindered by poor absorption and metabolism. A TDDS has various advantages compared to conventional methods of drug administration. It is less intrusive, more patient-friendly, and can circumvent first pass metabolism, as well as the corrosive acidic environment of the stomach, that happens when drugs are taken orally. Various approaches have been developed to enhance the transdermal permeability of different medicinal compounds. Recent improvements in TDDSs have enabled the accurate administration of APIs to their target sites by enhancing their penetration through the stratum corneum (SC), hence boosting the bioavailability of drugs throughout the body. Popular physical penetration augmentation methods covered in this review article include thermophoresis, iontophoresis, magnetophoresis, sonophoresis, needle-free injections, and microneedles. This review seeks to provide a concise overview of several methods employed in the production of TDDSs, as well as their evaluation, therapeutic uses, clinical considerations, and the current advancements intended to enhance the transdermal administration of drugs. These advancements have resulted in the development of intelligent, biodegradable, and highly efficient TDDSs.

A compact and low-frequency drive ultrasound transducer for facilitating cavitation-assisted drug permeation via skin

Low-frequency sonophoresis has emerged as a promising minimally invasive transdermal drug delivery method. However, effectively inducing cavitation on the skin surface with a compact, low-frequency ultrasound transducer poses a significant challenge. This paper presents a modified design of a low-frequency ultrasound transducer capable of generating ultrasound cavitation on the skin surfaces. The transducer comprises a piezoelectric ceramic disk and a bowl-shaped acoustic resonator. A conical slit structure was incorporated into the modified transducer design to amplify vibration displacement and enhance the maximum sound pressure. The FEM-based simulation results confirmed that the maximum sound pressure at the resonance frequency of 78 kHz was increased by 1.9 times that of the previous design. Ultrasound cavitation could be experimentally observed on the gel surface. Moreover, 3 min of ultrasound treatment significantly improved the caffeine permeability across an artificial membrane. These results demonstrated that this transducer holds promise for enhancing drug permeation by generating ultrasound cavitation on the skin surface.

Recent progress of microneedles in transdermal immunotherapy: A review

Since human skin is an immune organ, a large number of immune cells are distributed in the epidermis and the dermis of the skin. Transdermal immunotherapy shows great therapeutic advantages in innate immunotherapy and adaptive immunotherapy. To solve the problem that macromolecules are difficult to penetrate into the skin, the microneedle technology can directly break through the skin barrier using micron-sized needles in a non-invasive and painless way for transdermal drug delivery. Therefore, it is considered to be an effective technology to increase drug transdermal absorption. In this review, the types of preparation, the combinations with different techniques and the mechanisms of microneedles in transdermal immunotherapy were summarized. Compared with traditional immunotherapy like intramuscular injection and subcutaneous injection, the microneedle has many advantages in transdermal immunotherapy, such as reducing patient pain, enhancing vaccine stability, and inducing stronger immune responses. Although there are still some limitations to be solved, the application of microneedle technology in transdermal immunotherapy is undoubtedly a promising means of drug delivery.

High-Intensity Focused Ultrasound Enhances Drug Penetration into the Human Skin in the Franz Diffusion Cell

Purpose

High-intensity focused ultrasound (HIFU)-assisted drug delivery is a non-invasive tool to deliver drugs to targeted areas, currently used mainly for treating cancer and cardiovascular diseases. However, in terms of transdermal drug delivery, HIFU technology is still poorly understood. Accordingly, this study sought to investigate the effectiveness of HIFU on drug penetration into the skin using human skin tissues.

Methods

Gel-type drugs whose ingredient is glutathione were labelled with fluorescein isothiocyanate, in turn the drugs were allowed to penetrate to the human skin tissue in the Franz diffusion cell for 24 hours in control and HIFU treatment groups, and their fluorescence intensity was measured using a multiple microplate reader at one, two, six, and 24 hours after drug application. In addition, tissue slice analysis was performed in each tissue slice at 24 hours post-drug application. The % area, fluorescence intensity per area, and penetration depth of the drug were measured using a fluorescence microscope.

Results

The fluorescence intensity increased with time in all groups. Specifically, at 24 hours after drug application, the fluorescence intensity (a.u). of the 10-shot HIFU treatment group was significantly enhanced compared to that of the control group (p < 0.05). The tissue slice analysis demonstrated that the % area of fluorescent drug and the fluorescence intensity per area (a.u.) were all significantly increased in both HIFU treatment groups compared to the control group (p < 0.05, p < 0.001). In addition, the penetration depth (μm) also markedly rose in both HIFU treatment groups compared to the control group (p < 0.01, p < 0.05).

Conclusion

It was demonstrated for the first time that HIFU significantly facilitated topical drug penetration into the human skin, strongly implying that HIFU can be a useful option for transdermal drug delivery.

Transdermal drug delivery mediated by acoustic vortex beam

Ultrasound-mediated transdermal drug delivery exhibits various advantages such as biocompatibility, controllability and safety, which attracts plenty of interests within biomedical field. Current researches mostly emphasizes the acoustic cavitation generated by planar or focused waves while neglecting other physics that occur during transportation. Our experimental study illustrates the presence of an acoustic vortex (AV) beam that exhibits a lower acoustic intensity and typically means a lower dose of inertial cavitation, yet achieves a more efficient delivery. Such a result calls for the fundamental mechanism of ultrasound-mediated transdermal transfer using the AV beam. In this work, according to our knowledge, the AV beam is firstly introduced to ultrasound-mediated transdermal medication delivery. The transversal acoustic radiation force (T-ARF), which is the primary characteristic carried by the acoustic vortex beam, and its contribution to the transport enhancement are investigated. It is shown that a focused AV (FAV) beam with a maximal acoustic pressure of 200 kPa induces a pN-level T-ARF, which promotes the enlargement of pores on the stratum corneum and thereby enhances the permeability, as compared with a zero-order (non-vortex) counterpart. This contribution of the T-ARF is validated by the experimental transport on the cellulose membrane, which exhibits a significantly increased membrane porosity and delivery efficiency. The favorable results introduce the new degree of freedom into the ultrasound-mediated transdermal drug transport based on AV beam, and thereby promotes the development of a combined control strategy for more precise and efficient transdermal drug delivery in conjunction with the administration of acoustic cavitation.

Effectiveness of low-intensity pulsed ultrasound on osteoarthritis: molecular mechanism and tissue engineering

Osteoarthritis (OA) is distinguished by pathological alterations in the synovial membrane, articular cartilage, and subchondral bone, resulting in physical symptoms such as pain, deformity, and impaired mobility. Numerous research studies have validated the effectiveness of low-intensity pulsed ultrasound (LIPUS) in OA treatment. The periodic mechanical waves generated by LIPUS can mitigate cellular ischemia and hypoxia, induce vibration and collision, produce notable thermal and non-thermal effects, alter cellular metabolism, expedite tissue repair, improve nutrient delivery, and accelerate the healing process of damaged tissues. The efficacy and specific mechanism of LIPUS is currently under investigation. This review provides an overview of LIPUS's potential role in the treatment of OA, considering various perspectives such as the synovial membrane, cartilage, subchondral bone, and tissue engineering. It aims to facilitate interdisciplinary scientific research and further exploration of LIPUS as a complementary technique to existing methods or surgery. Ongoing research is focused on determining the optimal dosage, frequency, timing, and treatment strategy of LIPUS for OA. Additional research is required to clarify the precise mechanism of action and potential impacts on cellular, animal, and human systems prior to its integration into therapeutic applications.

Advancements in transdermal drug delivery: A comprehensive review of physical penetration enhancement techniques

Transdermal drug administration has grown in popularity in the pharmaceutical research community due to its potential to improve drug bioavailability, compliance among patients, and therapeutic effectiveness. To overcome the substantial barrier posed by the stratum corneum (SC) and promote drug absorption within the skin, various physical penetration augmentation approaches have been devised. This review article delves into popular physical penetration augmentation techniques, which include sonophoresis, iontophoresis, magnetophoresis, thermophoresis, needle-free injection, and microneedles (MNs) Sonophoresis is a technique that uses low-frequency ultrasonic waves to break the skin's barrier characteristics, therefore improving drug transport and distribution. In contrast, iontophoresis uses an applied electric current to push charged molecules of drugs inside the skin, effectively enhancing medication absorption. Magnetophoresis uses magnetic fields to drive drug carriers into the dermis, a technology that has shown promise in aiding targeted medication delivery. Thermophoresis is the regulated heating of the skin in order to improve drug absorption, particularly with thermally sensitive drug carriers. Needle-free injection technologies, such as jet injectors (JIs) and microprojection arrays, offer another option by producing temporary small pore sizes in the skin, facilitating painless and effective drug delivery. MNs are a painless, minimally invasive method, easy to self-administration, as well as high drug bioavailability. This study focuses on the underlying processes, current breakthroughs, and limitations connected with all of these approaches, with an emphasis on their applicability in diverse therapeutic areas. Finally, a thorough knowledge of these physical enhancement approaches and their incorporation into pharmaceutical research has the potential to revolutionize drug delivery, providing more efficient and secure treatment choices for a wide range of health-related diseases.

Effects of low-frequency ultrasound combined with anti-MRSA agents on the mouse model of pulmonary infection

The treatment of methicillin-resistant Staphylococcus aureus (MRSA)-induced pneumonia with antibiotics alone poses considerable challenges. To address these challenges, low-frequency ultrasound (LFU) emerges as a promising approach. In this study, a mouse pneumonia model was established through intratracheal injection of MRSA to investigate the therapeutic efficacy of LFU in combination with antibiotics. Minimal inhibitory concentration was assessed, and the distribution of antibiotics in the lung and plasma was determined using liquid chromatography coupled with mass spectrometry. Various parameters, including the survival rate, histopathology, lung bacterial clearance, and the expressions of cytokines and inflammation-related genes, were evaluated before and after treatment. Compared with the infection group, both the antibiotic-alone groups [vancomycin (VCM), linezolid, and contezolid (CZD)] and the groups in combination with LFU demonstrated an improvement in the survival status of mice. The average colony-forming units of lung tissue in the LFU combination groups were lower compared with the antibiotic-alone groups. While no significant changes in C-reactive protein and procalcitonin in plasma and bronchoalveolar lavage fluid were observed, histopathological results revealed reduced inflammatory damage in LFU combination groups. The secretion of interleukin-6 and tumor necrosis factor-alpha was decreased by the combination treatment, particularly in the VCM + LFU group. Furthermore, the expressions of MRSA virulence factors (hla and agrA) and inflammation-related genes (Saa3, Cxcl9, and Orm1) were further reduced by the combinations of LFU and antibiotics. Additionally, LFU treatment facilitated the distribution of VCM and CZD in mouse lung tissue at 30 and 45 min, respectively, after dosage.IMPORTANCETreating pneumonia caused by methicillin-resistant Staphylococcus aureus (MRSA) with antibiotics alone poses significant challenges. In this in vivo study, we present compelling evidence supporting the efficacy of low-frequency ultrasound (LFU) as a promising approach to overcome these obstacles. Our findings demonstrated that LFU enhanced the effectiveness of vancomycin, linezolid, and contezolid in an MRSA pneumonia model. The combination of LFU with anti-MRSA agents markedly improved the survival rate of mice, accelerated the clearance of pulmonary bacteria, reduced inflammatory injury, inhibited the production of MRSA endotoxin, and enhanced the distribution of antibiotics in lung tissue. The application of LFU in the treatment of pulmonary infections held substantial significance. We believe that readers of your journal will find this topic of considerable interest.

An Emerging Era: Conformable Ultrasound Electronics

Conformable electronics are regarded as the next generation of personal healthcare monitoring and remote diagnosis devices. In recent years, piezoelectric-based conformable ultrasound electronics (cUSE) have been intensively studied due to their unique capabilities, including nonradiative monitoring, soft tissue imaging, deep signal decoding, wireless power transfer, portability, and compatibility. This review provides a comprehensive understanding of cUSE for use in biomedical and healthcare monitoring systems and a summary of their recent advancements. Following an introduction to the fundamentals of piezoelectrics and ultrasound transducers, the critical parameters for transducer design are discussed. Next, five types of cUSE with their advantages and limitations are highlighted, and the fabrication of cUSE using advanced technologies is discussed. In addition, the working function, acoustic performance, and accomplishments in various applications are thoroughly summarized. It is noted that application considerations must be given to the tradeoffs between material selection, manufacturing processes, acoustic performance, mechanical integrity, and the entire integrated system. Finally, current challenges and directions for the development of cUSE are highlighted, and research flow is provided as the roadmap for future research. In conclusion, these advances in the fields of piezoelectric materials, ultrasound transducers, and conformable electronics spark an emerging era of biomedicine and personal healthcare.

Peptide-containing nanoformulations: Skin barrier penetration and activity contribution

Transdermal drug delivery presents a less invasive pathway, circumventing the need to pass through the gastrointestinal tract and liver, thereby reducing drug breakdown, initial metabolism, and gastrointestinal discomfort. Nevertheless, the unique composition and dense structure of the stratum corneum present a significant barrier to transdermal delivery. This article presents an overview of the current developments in peptides and nanotechnology to address this challenge. Initially, we sum up peptide-containing nanoformulations for transdermal drug delivery, examining them through the lenses of both inorganic and organic materials. Particular emphasis is placed on the diverse roles that peptides play within these nanoformulations, including conferring functionality upon nanocarriers and enhancing the biological efficacy of drugs. Subsequently, we summarize innovative strategies for enhancing skin penetration, categorizing them into passive and active approaches. Lastly, we discuss the therapeutic potential of peptide-containing nanoformulations in addressing a range of diseases, drawing insights from the biological activities and functions of peptides. Furthermore, the challenges hindering clinical translation are also discussed, providing valuable insights for future advancements in transdermal drug delivery.

Evolution of Transdermal Drug Delivery Devices and Novel Microneedle Technologies: A Historical Perspective and Review

The history of transdermal drug delivery is as old as humankind. Transdermal drug delivery has undergone three generations of development; the third generation has involved the use of medical devices and instruments. This review provides a historical perspective on the primary approaches employed in the three generations of transdermal drug delivery. In addition, we explore some of the recently developed transdermal techniques that are deemed promising in the field of drug delivery. We discuss how advances in these techniques have led to the development of devices for the delivery of a therapeutically effective amount of drug across human skin and highlight the limitations of the first- and second-generation drug delivery tools. As such, a review of the performance of these techniques and the toxicity of the devices used in transdermal drug delivery are considered. In the last section of the review, a discussion of the fabrication and operation of different types of microneedles is presented. The applications of microneedles in the sensing and delivery of various therapeutic agents are described in detail. Furthermore, an overview of the efficacy of microneedles as emerging tools for the controlled release of drugs is presented.

Applications and recent advances in transdermal drug delivery systems for the treatment of rheumatoid arthritis

Rheumatoid arthritis is a chronic, systemic autoimmune disease predominantly based on joint lesions with an extremely high disability and deformity rate. Several drugs have been used for the treatment of rheumatoid arthritis, but their use is limited by suboptimal bioavailability, serious adverse effects, and nonnegligible first-pass effects. In contrast, transdermal drug delivery systems (TDDSs) can avoid these drawbacks and improve patient compliance, making them a promising option for the treatment of rheumatoid arthritis (RA). Of course, TDDSs also face unique challenges, as the physiological barrier of the skin makes drug delivery somewhat limited. To overcome this barrier and maximize drug delivery efficiency, TDDSs have evolved in terms of the principle of transdermal facilitation and transdermal facilitation technology, and different generations of TDDSs have been derived, which have significantly improved transdermal efficiency and even achieved individualized controlled drug delivery. In this review, we summarize the different generations of transdermal drug delivery systems, the corresponding transdermal strategies, and their applications in the treatment of RA.

Advances and Prospects for Hydrogel-Forming Microneedles in Transdermal Drug Delivery

Transdermal drug delivery (TDD) is one of the key approaches for treating diseases, avoiding first-pass effects, reducing systemic adverse drug reactions and improving patient compliance. Microneedling, iontophoresis, electroporation, laser ablation and ultrasound facilitation are often used to improve the efficiency of TDD. Among them, microneedling is a relatively simple and efficient means of drug delivery. Microneedles usually consist of micron-sized needles (50-900 μm in length) in arrays that can successfully penetrate the stratum corneum and deliver drugs in a minimally invasive manner below the stratum corneum without touching the blood vessels and nerves in the dermis, improving patient compliance. Hydrogel-forming microneedles (HFMs) are safe and non-toxic, with no residual matrix material, high drug loading capacity, and controlled drug release, and they are suitable for long-term, multiple drug delivery. This work reviewed the characteristics of the skin structure and TDD, introduced TDD strategies based on HFMs, and summarized the characteristics of HFM TDD systems and the evaluation methods of HFMs as well as the application of HFM drug delivery systems in disease treatment. The HFM drug delivery system has a wide scope for development, but the translation to clinical application still has more challenges.

Innovative Strategies for Hair Regrowth and Skin Visualization

Today, about 50% of men and 15-30% of women are estimated to face hair-related problems, which create a significant psychological burden. Conventional treatments, including drug therapy and transplantation, remain the main strategies for the clinical management of these problems. However, these treatments are hindered by challenges such as drug-induced adverse effects and poor drug penetration due to the skin's barrier. Therefore, various efforts have been undertaken to enhance drug permeation based on the mechanisms of hair regrowth. Notably, understanding the delivery and diffusion of topically administered drugs is essential in hair loss research. This review focuses on the advancement of transdermal strategies for hair regrowth, particularly those involving external stimulation and regeneration (topical administration) as well as microneedles (transdermal delivery). Furthermore, it also describes the natural products that have become alternative agents to prevent hair loss. In addition, given that skin visualization is necessary for hair regrowth as it provides information on drug localization within the skin's structure, this review also discusses skin visualization strategies. Finally, it details the relevant patents and clinical trials in these areas. Together, this review highlights the innovative strategies for skin visualization and hair regrowth, aiming to provide novel ideas to researchers studying hair regrowth in the future.

Topical Delivery of Cell-Penetrating Peptide-Modified Human Growth Hormone for Enhanced Wound Healing

Protein drugs have been emerging as a class of promising therapeutics. However, their topical application has been limited by their high molecular weight and poor permeability to the cell membrane. In this study, we aimed to enhance human growth hormone (hGH) permeability for topical application by conjugation of TAT peptide, a cell-penetrating peptide, to hGH via crosslinker. After TAT was conjugated to hGH, TAT-hGH was purified by affinity chromatography. TAT-hGH significantly increased cell proliferation compared with the control. Interestingly, the effect of TAT-hGH was higher than hGH at the same concentration. Furthermore, the conjugation of TAT to hGH enhanced the permeability of TAT-hGH across the cell membrane without affecting its biological activity in vitro. In vivo, the topical application of TAT-hGH into scar tissue markedly accelerated wound healing. Histological results showed that TAT-hGH dramatically promoted the re-epithelialization of wounds in the initial stage. These results demonstrate TAT-hGH as a new therapeutic potential drug for wound healing treatment. This study also provides a new method for topical protein application via enhancement of their permeability.

NIR light-activatable dissolving microneedle system for melanoma ablation enabled by a combination of ROS-responsive chemotherapy and phototherapy

BACKGROUND

As a consequence of the aggressive and recurrent nature of melanoma, repeated, multimodal treatments are often necessary to cure the disease. While microneedle (MN)-based transdermal drug delivery methods can allow drugs to avoid first-pass metabolism and overcome the stratum corneum barrier, the main challenges of these delivery methods entail the lack of controlled drug release/activation and effective imaging methods to guide the entire treatment process.

METHODS

To enable a transdermal delivery method with controllable drug release/activation and effective imaging guidance, we designed a near-infrared (NIR) photoactivatable, dissolving MN system comprising dissolvable polyvinylpyrrolidone MNs arrays (MN-pB/I) containing liposomes that were co-loaded with the photosensitizer indocyanine green (ICG) and the reactive oxygen species (ROS)-activatable prodrug of doxorubicin (pB-DOX).

RESULTS

After applying the MN patch to the tumor site, the liposomes concentrated in the needle tips were released into the tumor tissue and distributed evenly upon dissolution of the matrix to enable targeted delivery. Then, the ROS produced by ICG after exposure to NIR light performed photodynamic therapy and activated the pB-DOX for chemotherapy by cleaving the prodrug moiety and converting it to DOX. As a dye, ICG was also used to guide the treatment regimens and monitor the efficacy by fluorescence and photoacoustic imaging. The growth of the tumors in the MN-pB/I group were inhibited by 93.5%, while those were only partially inhibited in the control groups. Negligible treatment-induced side effects and cardiotoxicity were observed.

CONCLUSION

The MN-pB/I represents a multimodal, biocompatible theragnostic system with spatiotemporal control that was capable of ablating melanoma tumors after a single dose, providing a promising candidate for clinical melanoma therapy.

Silk Nanocarrier with Tunable Size to Improve Transdermal Capacity for Hydrophilic and Hydrophobic Drugs

Transdermal drug delivery is an attractive option for multiple disease therapies as it reduces adverse reactions and improves patient compliance. Water-dispersible β-sheet rich silk nanofiber carriers have hydrophobic properties that benefit transdermal delivery but still show inferior transdermal capacities. Thus, hydrophobic silk nanofibers were fabricated to fine-tune their size and endow them with desirable transdermal delivery capacities. Silk nanocarrier length was shortened from 2000 nm to approximately 40 nm after ultrasonic treatment. In vitro human skin and in vivo animal studies revealed different transdermal behaviors for silk nanocarriers at different nanosizes. Silk nanocarriers passed slowly through the corneum without destroying the corneum structure. Improved transdermal capacity was achieved for smaller size carriers. Both hydrophilic and hydrophobic drugs could be loaded onto silk nanocarriers, suggesting a promising future for different disease therapies. No cytotoxicity and skin irritation were identified for silk nanocarriers, which strengthened their superiority as transdermal carriers. Therefore, silk nanocarriers <100 nm may promote the percutaneous absorption of active cargos for disease therapy and cosmetic applications.

Pharmaceutical based cosmetic serums

The growth and demand for cosmeceuticals (cosmetic products that have medicinal or drug-like benefits) have been enhanced for the last few decades. Lately, the newly invented dosage form, i.e., the pharmaceutical-based cosmetic serum has been developed and widely employed in various non-invasive cosmetic procedures. Many pharmaceutical-based cosmetic serums contain natural active components that claim to have a medical or drug-like effect on the skin, hair, and nails, including anti-aging, anti-wrinkle, anti-acne, hydrating, moisturizing, repairing, brightening and lightening skin, anti-hair fall, anti-fungal, and nail growth effect, etc. In comparison with other pharmaceutical-related cosmetic products (creams, gels, foams, and lotions, etc.), pharmaceutical-based cosmetic serums produce more rapid and incredible effects on the skin. This chapter provides detailed knowledge about the different marketed pharmaceutical-based cosmetic serums and their several types such as facial serums, hair serums, nail serums, under the eye serum, lip serum, hand, and foot serum, respectively. Moreover, some valuable procedures have also been discussed which provide prolong effects with desired results in the minimum duration of time after the few sessions of the serum treatment.

Superior Replacement of Medicinal Gel With Ayurvedic Nanogel as a Coupling Medium for Electrotherapeutic Treatment of Osteoarthritis: A Review Article

Osteoarthritis is a disabling condition globally, affecting a major population. The non-invasive conservative management of osteoarthritis is majorly catered to by physical therapy rehabilitation. Research has been conducted to evaluate the impact of the most commonly used electrotherapy modality, therapeutic ultrasound, on reducing pain and increasing functional activities in individuals suffering from osteoarthritis, but the condition is still, after over two decades of research, growing rapidly in its prevalence. Therefore, the aim of our study was to analyze the literature and compare the evolving trends in coupling medium used for the application of therapeutic ultrasound in arthritic conditions of musculoskeletal origin. Databases of PubMed, Web of Science, Embase, Pedro, and Cochrane were searched till June 2022. The outcome measures used were to detect the status of pain and improvement in functional status. Overall ultrasound therapy adjunct to exercise program was found to be superior to either ultrasound therapy or exercise program alone for the management of pain and functional status of the patients. Additionally, phonophoresis was deduced to have shown better pain relief than conventional ultrasound. Phonophoresis was done using non-steroidal anti-inflammatory drugs and Ayurvedic medicinal herbs in the form of Nano gel.

Synergistic effect of low-frequency ultrasound and antibiotics on the treatment of Klebsiella pneumoniae pneumonia in mice

The antibiotic‐resistant Klebsiella pneumoniae (Kp) has become a significant crisis in treating pneumonia. Low‐frequency ultrasound (LFU) is promising to overcome the obstacles. Mice were infected with bioluminescent Kp Xen39 by intratracheal injection to study the therapeutic effect of LFU in combination with antibiotics. The counts per second (CPS) were assessed with an animal biophoton imaging system. Bacterial clearance, histopathology, and the concentrations of cytokines were determined to evaluate the therapeutic effect. LC–MS/MS was used to detect the distribution of antibiotics in the lung and plasma. LFU in combination with meropenem (MEM) or amikacin (AMK) significantly improved the behavioural state of mice. The CPS of the LFU combination group were more significantly decreased compared with those of the antibiotic alone groups. The average colony‐forming units of lung tissue in the LFU combination groups were also lower than those of the antibiotic groups. Although no significant changes of cytokines (IL‐6 and TNF‐α) in plasma and bronchoalveolar lavage fluid were observed, LFU in combination with antibiotics showed less inflammatory damage from histopathological results compared with the antibiotic‐alone groups. Moreover, 10 min of LFU treatment promoted the distribution of MEM and AMK in mouse lung tissue at 60 and 30 min, respectively, after dosage. LFU could enhance the effectiveness of MEM and AMK in the treatment of Kp‐induced pneumonia, which might be attributed to the fact that LFU could promote the distribution of antibiotics in lung tissue and reduce inflammatory injury.

Effect of High-Frequency Ultrasound on Targeted Liposomes

Delivering highly toxic drugs inside a safe carrier to tumors while achieving controlled and effective drug release at the targeted sites represents an attractive approach to enhance drug efficiency while reducing its undesirable side effects. Functionalization of highly biocompatible nanocarriers such as liposomes conjugated with targeting moieties enhances their ability to target specific cancer cells overexpressing the targeted receptors. Furthermore, upon their accumulation at the target site, high-frequency ultrasound (HFUS) can be used to stimulate the controlled release of the loaded drugs. Here, the US-mediated drug release from calcein-loaded non-pegylated, pegylated as well as targeted-pegylated liposomes modified with human serum albumin (HSA) and transferrin (Tf) was investigated. HFUS at two different frequencies (1 MHz and 3 MHz) was found to trigger calcein release, with higher release rates recorded at the lower frequency (i.e., 1 MHz) compared to the higher frequency (i.e., 3 MHz) despite a higher power density. Pegylation was found to enhance liposomal sensitivity to HFUS. In addition, targeted pegylated liposomes were more susceptible to HFUS than non-targeted pegylated (control) liposomes. These findings show that pegylation and targeting moieties directly influence liposomal sensitivity to HFUS. Therefore, combining targeted-pegylated liposomes with HFUS represents a promising controlled and effective drug delivery system.

Biocoating-A Critical Step Governing the Oral Delivery of Polymeric Nanoparticles

Decades of research into the topic of oral nanoparticle (NP) delivery has still not provided a clear consensus regarding which properties produce an effective oral drug delivery system. The surface properties-charge and bioadhesiveness-as well as in vitro and in vivo correlation seem to generate the greatest number of disagreements within the field. Herein, a mechanism underlying the in vivo behavior of NPs is proposed, which bridges the gaps between these disagreements. The mechanism relies on the idea of biocoating-the coating of NPs with mucus-which alters their surface properties, and ultimately their systemic uptake. Utilizing this mechanism, several coated NPs are tested in vitro, ex vivo, and in vivo, and biocoating is found to affect NPs size, zeta-potential, mucosal diffusion coefficient, the extent of aggregation, and in vivo/in vitro/ex vivo correlation. Based on these results, low molecular weight polylactic acid exhibits a 21-fold increase in mucosal diffusion coefficient after precoating as compared to uncoated particles, as well as 20% less aggregation, and about 30% uptake to the blood in vivo. These discoveries suggest that biocoating reduces negative NP charge which results in an enhanced mucosal diffusion rate, increased gastrointestinal retention time, and high systemic uptake.

Microbubbles Stabilized by Protein Shell: From Pioneering Ultrasound Contrast Agents to Advanced Theranostic Systems

Ultrasound is a widely-used imaging modality in clinics as a low-cost, non-invasive, non-radiative procedure allowing therapists faster decision-making. Microbubbles have been used as ultrasound contrast agents for decades, while recent attention has been attracted to consider them as stimuli-responsive drug delivery systems. Pioneering microbubbles were Albunex with a protein shell composed of human serum albumin, which entered clinical practice in 1993. However, current research expanded the set of proteins for a microbubble shell beyond albumin and applications of protein microbubbles beyond ultrasound imaging. Hence, this review summarizes all-known protein microbubbles over decades with a critical evaluation of formulations and applications to optimize the safety (low toxicity and high biocompatibility) as well as imaging efficiency. We provide a comprehensive overview of (1) proteins involved in microbubble formulation, (2) peculiarities of preparation of protein stabilized microbubbles with consideration of large-scale production, (3) key chemical factors of stabilization and functionalization of protein-shelled microbubbles, and (4) biomedical applications beyond ultrasound imaging (multimodal imaging, drug/gene delivery with attention to anticancer treatment, antibacterial activity, biosensing). Presented critical evaluation of the current state-of-the-art for protein microbubbles should focus the field on relevant strategies in microbubble formulation and application for short-term clinical translation. Thus, a protein bubble-based platform is very perspective for theranostic application in clinics.

Polysaccharide-Based Transdermal Drug Delivery

Materials derived from natural plants and animals have great potential for transdermal drug delivery. Polysaccharides are widely derived from marine, herbal, and microbial sources. Compared with synthetic polymers, polysaccharides have the advantages of non-toxicity and biodegradability, ease of modification, biocompatibility, targeting, and antibacterial properties. Currently, polysaccharide-based transdermal drug delivery vehicles, such as hydrogel, film, microneedle (MN), and tissue scaffolds are being developed. The addition of polysaccharides allows these vehicles to exhibit better-swelling properties, mechanical strength, tensile strength, etc. Due to the stratum corneum’s resistance, the transdermal drug delivery system cannot deliver drugs as efficiently as desired. The charge and hydration of polysaccharides allow them to react with the skin and promote drug penetration. In addition, polysaccharide-based nanotechnology enhances drug utilization efficiency. Various diseases are currently treated by polysaccharide-based transdermal drug delivery devices and exhibit promising futures. The most current knowledge on these excellent materials will be thoroughly discussed by reviewing polysaccharide-based transdermal drug delivery strategies.

Quantitative Analysis of Acoustic Pressure for Sonophoresis and Its Effect on Transdermal Penetration

Ultrasound facilitates the penetration of macromolecular compounds through the skin and offers a promising non-invasive technique for transdermal delivery. However, technical difficulties in quantifying ultrasound-related parameters have restricted further analysis of the sonophoresis mechanism. In this study, we devise a bolt-clamped Langevin transducer-based sonophoresis device that enables us to measure with a thin lead zirconate titanate (PZT) sensor. One-dimensional acoustic theory accounting for wave interaction at the skin interface indicates that the acoustic pressure and cavitation onset on the skin during sonophoresis are sensitive to the subcutaneous support, meaning that there is a strong need to perform the pressure measurement in an experimental environment replacing the human body. From a series of the experiments with our new device, the transdermal penetration of polystyrene, silica and gold nanoparticles is found to depend on the size and material of the particles, as well as the hardness of the subcutaneous support material. We speculate from the acoustic pressure measurement that the particles' penetration results from the mechanical action of cavitation.

Stretchable Electronic Facial Masks for Sonophoresis

We introduce a stretchable electronic facial mask (SEFM) as a platform for facial healthcare, which can integrate with various sensors and actuators. As a demonstration, an SEFM for sonophoresis enabling the promotion of the delivery effect of a drug mask is developed. To overcome the technique challenges, several approaches including the design of the joined silicone layer by two planar half-face portions and the single-side soft pressing (SSSP) technique for encapsulation are exploited in this work, which could be extended to the design and fabrication of other stretchable electronics. The mechanical, thermal, electrical, and ultrasonic characteristics of the SEFM are all verified by the finite element analysis and experiments. Finally, we prove the effect of the SEFM on accelerating the delivery of hyaluronic acid (HA) through animal experiments and confirm that the SEFM can enhance the skin moisture content by 20% via human facial experiments.

Intradermal injection of lidocaine with a microneedle device to provide rapid local anaesthesia for peripheral intravenous cannulation: A randomised open-label placebo-controlled clinical trial

Background

Peripheral venous cannulation is one of the most common procedures in medicine. It is associated with noticeable pain and apprehension, although in most cases it is performed without any anesthesia due to lack of a painless, cost-effective option, which would provide rapid local anesthesia with subsequent significant reduction in the experienced pain. We conducted an open-label placebo-controlled clinical trial to evaluate the efficacy and safety of a 2% lidocaine injection using the commercially available microneedle device MinronJet600 (NanoPass Technologies Ltd, Israel) to achieve rapid local anesthesia prior to peripheral venous cannulation.

Methods

One hundred and two subjects were randomly allocated into two groups. In the first group, 100μL of lidocaine hydrochloride (2%) was injected intradermally to subjects using the MicronJet600 device in the left arm (MJ-Lido) and 100μL of saline was injected intradermally using the device in the right arm (MJ-Saline). In the second group, 100μL of lidocaine hydrochloride (2%) was injected using the MicronJet600 device into the left arm (MJ-Lido), with no injection into the right arm of subjects (No pretreatment). In both groups the intradermal injection was performed at the cannulation site prior to insertion of a 18G cannula into a median cubital vein in both arms. As a primary variable, a score of cannulation-induced pain was indicated by subjects using a 100-point visual analog scale immediately after cannulation. As a secondary variable, subjects in Group 2 also indicated their preference to receive the anaesthetic injection with MicronJet600 in the future by using the 5-point Likert scale. Also, as a secondary variable, the duration of skin numbness after lidocaine injection was indicated by performing a superficial pin-prick with a 27G needle at 15, 30 and 45 minutes, at distances of 1, 2 and 3 centimeters from the injection site.

Results

A significant pain reduction (11.0-fold) was achieved due to the lidocaine injection compared to the cannulation without any pretreatment (p< 0.005). After the lidocaine injection the anesthesia was effective up to 2 centimeters from the injection site and remained for up to 30 minutes. Eighty percent of subjects from the second group preferred cannulation after the lidocaine injection over cannulation without any pretreatment. No significant side effects were identified.

Conclusion

Intradermal injection of anaesthetic with Micronjet600 was found to be a safe and effective option for providing rapid local anesthesia for peripheral intravenous cannulation.

Trial regiatration

The clinical trial was registered, before the patient enrollment began, in the Research Registry publicly accessible database (registration identifier: researchregistry4662). Also, the trial was registered in ClinicalTrials.gov (registration identifier: NCT05108714) after its completion.

Ionic liquids as effective additives to enhance the solubility and permeation for puerarin and ferulic acid

Ionic liquids, especially the cholinium-amino acid-based ionic liquids (CHAAILs), have recently been found to be effective ingredients in formulation of transdermal drug delivery system. In this work, we synthesized six CHAAILs, and investigated their ability to enhance the solubility and permeation of two active pharmaceutic ingredients (APIs), i.e. ferulic acid and puerarin. The solubility measurements showed that a low amount of CHAAILs can significantly increase the solubility of APIs. Moreover, the effective enhancement of permeation of APIs across a polyethersulfone (PES) membrane was achieved at low concentration (4 mg ml⁻¹) of CHAAILs. It is more worthwhile that the presence of CHAAIL brings much less cytotoxicity as compared to traditional types of ionic liquids. Therefore, CHAAILs can be considered as great potential candidates of green and effective additives in transdermal drug delivery systems.

Cholinium-animo acid based ionic liquids displayed high efficiency in enhancing the solubility and permeation ability of active pharmaceutic ingredients.

Metal-Organic Framework (MOF)-Based Ultrasound-Responsive Dual-Sonosensitizer Nanoplatform for Hypoxic Cancer Therapy

Sonodynamic therapy (SDT), which uses reactive oxygen species to target tumors, has shown promise in the management of unresectable cancers. However, the hypoxic tumor environment limits SDT efficiency, making complete tumor destruction challenging. Here, a dual-sonosensitizer nanoplatform is developed by loading an alkyl radical generator (2,2-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, AIPH) onto a zirconium metal-organic framework (Zr-MOF). The Zr-MOF@AIPH nanoparticles (NPs) can produce singlet oxygen, which can kill tumor cells under normoxic conditions, as well as alkyl radicals, which can kill tumor cells under both normoxic and hypoxic conditions. The combination of these free radicals further enhances SDT efficiency. Meanwhile, the nitrogen generated owing to AIPH decomposition can reduce the cavitation threshold and enhance the acoustic cavitation effect, thereby promoting NP penetration at the tumor site. Moreover, Zr-MOF@AIPH NPs exhibit good photoacoustic, fluorescence, and ultrasound imaging abilities due to their porphyrin-based structure and the nitrogen generated, which can remotely control NP delivery and determine the optimal therapeutic time window, ensuring the maximization of SDT efficiency. In vitro and in vivo examinations prove the superior antitumor efficacy, excellent biocompatibility, and favorable imaging ability of Zr-MOF@AIPH. This study spearheads the charge toward improving SDT efficacy in hypoxic environments via a combination of complementary sonosensitizers.

Transdermal delivery for gene therapy

Gene therapy is a critical constituent of treatment approaches for genetic diseases and has gained tremendous attention. Treating and preventing diseases at the genetic level using genetic materials such as DNA or RNAs could be a new avenue in medicine. However, delivering genes is always a challenge as these molecules are sensitive to various enzymes inside the body, often produce systemic toxicity, and suffer from off-targeting problems. In this regard, transdermal delivery has emerged as an appealing approach to enable a high efficiency and low toxicity of genetic medicines. This review systematically summarizes outstanding transdermal gene delivery methods for applications in skin cancer treatment, vaccination, wound healing, and other therapies.

Microneedle-Mediated Vaccination: Innovation and Translation

Vaccine administration by subcutaneous or intramuscular injection is the most commonly prescribed route for inoculation, however, it is often associated with some deficiencies such as low compliance, high professionalism, and risk of infection. Therefore, the application of microneedles for vaccine delivery has gained widespread interests in the past few years due to its high compliance, minimal invasiveness, and convenience. This review focuses on recent advances in the development and application of microneedles for vaccination based on different delivery strategies, and introduces the current status of microneedle-mediated vaccination in clinical translation. The prospects for its application including opportunities and challenges are further discussed.

Topically applied liposome-in-hydrogels for systematically targeted tumor photothermal therapy

Transdermal drug delivery for local or systemic therapy provides a potential anticancer modality with a high patient compliance. However, the drug delivery efficiency across the skin is highly challenging due to the physiological barriers, which limit the desired therapeutic effects. In this study, we prepared liposome-in-hydrogels containing a tumor targeting photosensitizer IR780 (IR780/lipo/gels) for tumor photothermal therapy (PTT). The formulation effectively delivered IR780 to subcutaneous tumor and deep metastatic sites, while the hydrogels were applied on the skin overlying the tumor or on an area of distant normal skin. The photothermal antitumor activity of topically administered IR780/lipo/gels was evaluated following laser irradiation. We observed significant inhibition of the rate of the tumor growth without any toxicity associated with the topical administration of hydrogels. Collectively, the topical administration of IR780/lipo/gels represents a new noninvasive and safe strategy for targeted tumor PTT.

Review of Oxygenation with Nanobubbles: Possible Treatment for Hypoxic COVID-19 Patients

The coronavirus disease (COVID-19) pandemic, which has spread around the world, caused the death of many affected patients, partly because of the lack of oxygen arising from impaired respiration or blood circulation. Thus, maintaining an appropriate level of oxygen in the patients' blood by devising alternatives to ventilator systems is a top priority goal for clinicians. The present review highlights the ever-increasing application of nanobubbles (NBs), miniature gaseous vesicles, for the oxygenation of hypoxic patients. Oxygen-containing NBs can exert a range of beneficial physiologic and pharmacologic effects that include tissue oxygenation, as well as tissue repair mechanisms, antiinflammatory properties, and antibacterial activity. In this review, we provide a comprehensive survey of the application of oxygen-containing NBs, with a primary focus on the development of intravenous platforms. The multimodal functions of oxygen-carrying NBs, including antimicrobial, antiinflammatory, drug carrying, and the promotion of wound healing are discussed, including the benefits and challenges of using NBs as a treatment for patients with acute hypoxemic respiratory failure, particularly due to COVID-19.

Measure method of effective diffusion in gas oscillating in channels of variable radius or porous medium

The paper discusses a new technique for measuring the diffusion coefficient of vapor of a volatile fluid in air in long straight channels or porous media. The proposed experimental technique is universal and allows a) determining the coefficient of molecular diffusion of vapor of a volatile liquid in air; b) calculating the coefficient of effective diffusion of vapor in oscillating air. The proposed technique was tested in the study of the diffusion of 2-propanol vapor in air at rest and oscillating air in a channel of variable radius and a porous medium consisting of randomly packed hard spheres of equal diameter and was found to be relevant. Initial experiments with a porous medium show that the proposed experimental technique can also be used to estimate the diffusive tortuosity of porous media. The results of studies, finished and planned, are useful for understanding the physical processes taking place in various technical operations including wood and food drying, drug delivery, etc.•

The new experimental technique provides accurate measurement of the molecular diffusion coefficient of vapor of a volatile fluid in air.

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The experimental setup allows measuring the enhanced mass transfer of vapor of a volatile fluid in oscillating air in a straight channel of constant/variable radius and a porous medium.

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The additional advantage of the present technique is that it enables the estimation of the diffusive tortuosity of a porous medium.

Glucose-Sensitive Core-Cross-Linked Nanoparticles Constructed with Polyphosphoester Diblock Copolymer for Controlling Insulin Delivery

This work aims to construct biocompatible, biodegradable core-cross-linked and insulin-loaded nanoparticles which are sensitive to glucose and release insulin via cleavage of the nanoparticles in a high-concentration blood glucose environment. First, a polyphosphoester-based diblock copolymer (PBYP-g-Gluc)-b-PEEP was prepared via ring-opening copolymerization (ROP) and the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) in which PBYP and PEEP represent the polymer segments from 2-(but-3-yn-1-yloxy)-2-oxo-1,3,2-dioxaphospholane and 2-ethoxy-2-oxo-1,3,2-dioxaphospholane, respectively, and Gluc comes from 2-azidoethyl-β-d-glucopyranoside (Gluc-N3) that grafted with PBYP. The structure and molecular weight of the copolymer were characterized by 1H NMR, 31P NMR, GPC, FT-IR, and UV-vis measurements. The amphiphilic copolymer could self-assemble into core-shell uncore-cross-linked nanoparticles (UCCL NPs) in aqueous solutions and form core-cross-linked nanoparticles (CCL NPs) after adding cross-linking agent adipoylamidophenylboronic acid (AAPBA). Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to study the self-assembly behavior of the two kinds of NPs and the effect of different Gluc group contents on the size of NPs further to verify the stability and glucose sensitivity of CCL NPs. The ability of NPs to load fluorescein isothiocyanate-labeled insulin (FITC-insulin) and their glucose-triggered release behavior were detected by a fluorescence spectrophotometer. The results of methyl thiazolyl tetrazolium (MTT) assay and hemolysis activity experiments showed that the CCL NPs had good biocompatibility. An in vivo hypoglycemic study has shown that FITC-insulin-loaded CCL NPs could reduce blood glucose and have a protective effect on hypoglycemia. This research provides a new method for constructing biodegradable and glucose-sensitive core-cross-linked nanomedicine carriers for controlled insulin release.

Molecular perspective of efficiency and safety problems of chemical enhancers: bottlenecks and recent advances

Chemical penetration enhancer (CPE) is a preferred approach to improve drug permeability through the skin, due to its unique advantages of simple use and high compatibility. However, CPEs efficiency and safety problems frequently arise, which greatly restrains the further application in transdermal drug delivery systems (TDDS). To get access to the root of problems, the efficiency and safety of CPEs are reviewed especially from molecular perspectives, which include (1) the possible factors of CPEs low efficiency; (2) the possible contribution of CPEs in the evolution of safety problems such as skin irritation and allergic reaction; (3) the interactive relationship between CPEs efficiency and safety, as well as the bottlenecks of achieving their balance. More importantly, based on these, recent advances are summarized in improving efficiency or safety of CPEs, which offers a guidance of rationally selecting CPEs in future research.

Topical delivery of gambogic acid assisted by the combination of low-frequency ultrasound and chemical enhancers for chemotherapy of cutaneous melanoma

Anti-cutaneous melanoma activity of the skin-delivered gambogic acid (GA) has been reported in our previous study. However, it is difficult for GA to diffuse passively through intact skin without any enhancement means. In this study, a combination of chemical enhancers (EN: azone and propylene glycol) and physical ultrasound (US) was used to improve the percutaneous permeation of GA and enhance the anti-melanoma activity. The enhancement effect of the combination of EN and US (EN-US) on GA in vitro and in vivo was studied, and the enhancement mechanism and skin irritation were also evaluated. We showed that the parameters of US application at a constant frequency (30 kHz) with a duty cycle of 100% and intensity of 1.75 W/cm² for 20 min were optimal. In vitro, EN-US showed a considerable enhancement of the permeation of GA, and the enhancement effect was stronger than that with the use of EN or US alone. In vivo antitumor study showed that the tumor growth was significantly inhibited after percutaneous administration of GA by EN-US, more than in the intravenous injection group. The penetration enhancement mechanism revealed that EN-US not only altered the structure of lipid bilayers and keratins to reduce the barrier effect of the stratum corneum but also produced diffusion channels in the skin under the cavitation effect of US, thereby promoting the skin penetration of GA. In addition, there was no observable skin irritation in mice after treatment with EN-US. Our study demonstrated that the combination of EN and US improved the skin permeation and retention of GA to enhance the anti-melanoma activity. This method also provides technical guidance for the future development of topical and transdermal therapeutic system of GA.

Combined effect of sonophoresis and a microemulsion on the dermal delivery of celecoxib

The aim of this study was to evaluate the intensity of sonophoresis at which the skin penetration of celecoxib was enhanced and to study the combined effects of sonophoresis and microemulsion application on the dermal delivery of celecoxib. The sonophoresis intensity that provided the highest skin penetration enhancement of celecoxib was 30 Watts/cm². However, the combination of sonophoresis and the microemulsion resulted in a decrease in celecoxib skin penetration. The results of a confocal laser scanning microscopy study using the colocalization analysis of multifluorescently labeled particles revealed that the reduction in skin penetration of celecoxib from the combination of sonophoresis and a microemulsion resulted from a decrease in transfollicular penetration, which is the major skin absorption pathway of the microemulsion.

Atmospheric Pressure Plasma Irradiation Facilitates Transdermal Permeability of Aniline Blue on Porcine Skin and the Cellular Permeability of Keratinocytes with the Production of Nitric Oxide

The transdermal delivery system of nutrients, cosmetics, and drugs is particularly attractive for painless, noninvasive delivery and sustainable release. Recently, atmospheric pressure plasma techniques have been of great interest to improve the drug absorption rate in transdermal delivery. Currently, plasma-mediated changes in the lipid composition of the stratum corneum are considered a possible mechanism to increase transdermal permeability. Nevertheless, its molecular and cellular mechanisms in transdermal delivery have been largely confined and still veiled. Herein, we present the effects of cold plasma on transdermal transmission on porcine skin and the cellular permeability of keratinocytes and further demonstrate the production of nitric oxide from keratinocytes. Consequently, argon plasma irradiation for 60 s resulted in 2.5-fold higher transdermal absorption of aniline blue dye on porcine skin compared to the nontreated control. In addition, the plasma-treated keratinocytes showed an increased transmission of high-molecular-weight molecules (70 and 150 kDa) with the production of nitric oxide. Therefore, these findings suggest a promoting effect of low-temperature plasma on transdermal absorption, even for high-molecular-weight molecules. Moreover, plasma-induced nitric oxide from keratinocytes is likely to regulate transdermal permeability in the epidermal layer.

Physical Enhancement? Nanocarrier? Current Progress in Transdermal Drug Delivery

A transdermal drug delivery system (TDDS) is a method that provides drug adsorption via the skin. TDDS could replace conventional oral administration and blood administration because it is easily accessible. However, it is still difficult to design efficient TDDS due to the high barrier property of skin covered with stratum corneum, which inhibits the permeation of drug molecules. Thus far, TDDS methods by applying physical stimuli such as microneedles and chemical stimuli such as surfactants have been actively developed. However, it has been hard to avoid inflammation at the administration site because these methods partially destroy the skin tissue. On the other hand, TDDS with nanocarriers minimizing damage to the skin tissues has emerged together with the development of nanotechnology in recent years. This review focuses on current trends in TDDS.

Enhancement strategies for transdermal drug delivery systems: current trends and applications

Transdermal drug delivery systems have become an intriguing research topic in pharmaceutical technology area and one of the most frequently developed pharmaceutical products in global market. The use of these systems can overcome associated drawbacks of other delivery routes, such as oral and parenteral. The authors will review current trends, and future applications of transdermal technologies, with specific focus on providing a comprehensive understanding of transdermal drug delivery systems and enhancement strategies. This article will initially discuss each transdermal enhancement method used in the development of first-generation transdermal products. These methods include drug/vehicle interactions, vesicles and particles, stratum corneum modification, energy-driven methods and stratum corneum bypassing techniques. Through suitable design and implementation of active stratum corneum bypassing methods, notably microneedle technology, transdermal delivery systems have been shown to deliver both low and high molecular weight drugs. Microneedle technology platforms have proven themselves to be more versatile than other transdermal systems with opportunities for intradermal delivery of drugs/biotherapeutics and therapeutic drug monitoring. These have shown that microneedles have been a prospective strategy for improving transdermal delivery systems.

Ultrashort Cell-Penetrating Peptides for Enhanced Sonophoresis-Mediated Transdermal Transport

The skin is a key site for drug administration because of its large surface area and noninvasive accessibility. However, the dermal architecture serves as an excellent barrier, protecting from external mechanical, chemical, microbial, and physical perturbations. Most drugs display poor permeability through this barrier, thus making dermal and subdermal delivery challenging. Cell-penetrating peptides (CPPs), a diverse group of relatively short cationic and amphipathic membrane-interacting peptides, are fast becoming an important class of drug carriers and could potentially be developed for the dermal delivery of active molecules. However, the mechanism of CPP transdermal delivery is not fully understood, and there is a genuine need for a minimal model to understand this important phenomenon. Here, we demonstrate the potent membrane interactions of a minimal four-amino-acid-long CPP as well as the significance of guanidinium patterning and cationic nature of this palindromic peptide on its bioactivity. Furthermore, we demonstrate the biocompatibility of this peptide as well as its rapid cellular uptake and endosomal distribution. Finally, by utilizing a porcine full-thickness skin model, we demonstrate the substantial independent dermal and sonophoresis-based transdermal penetration of this minimal model. These results provide a minimal model for CPPs which can be easily manipulated for further biophysical and biochemical evaluations as well as a potent functional CPP with excellent skin permeability, which can be utilized for a wide variety of cosmetic and medical applications.