Heat: A Highly Efficient Skin Enhancer for Transdermal Drug Delivery

Preparation and characterization of dissolving hyaluronic acid composite microneedles loaded micelles for delivery of curcumin

In order to improve the bioavailability of curcumin (Cur) and patient compliance, a type of novel hyaluronic acid (HA) composite microneedles containing Cur-loaded micelles was designed in this paper. On the one hand, the microneedles matrix solution was prepared by screening the optimal concentration of HA and the better proportion of HA to sodium carboxymethyl starch (CMS-Na). On the other hand, the amphiphilic polymer, named as Quercetin-Dithiodipropionic Acid-Oligomeric Hyaluronic Acid (Que-DA-oHA), was synthesized and characterized using ¹H-NMR. Subsequently, the dialysis method was used to prepare Cur-loaded Que-DA-oHA micelles with an average size of 172.6 ± 11.4 nm and zeta potential of - 33.71 ± 0.45 mV. A micromolding process was used to prepare the micelle-loaded HA composite microneedles. It had been found that when the concentration of HA was 200 mg/mL and the mass ratio of HA to CMS-Na was 2:1, the prepared HA composite microneedles had good mechanical strength. In-skin dissolution kinetics showed that the micelle-loaded HA composite microneedles could dissolve quickly in the skin. In vitro permeation study indicated that the microneedles delivered 74.7% of their drug load over 6 h, which exhibited remarkable drug permeation properties in a short time. Here, we creatively combined micellar technology with microneedle technology to rapidly deliver Cur transdermally for diseases treatment such as melanoma. Graphical abstract.

Functional Fibers, Composites and Textiles Utilizing Photothermal and Joule Heating

This review focuses on the mechanism of adjusting the thermal environment surrounding the human body via textiles. Recently highlighted technologies for thermal management are based on the photothermal conversion principle and Joule heating for wearable electronics. Recent innovations in this technology are described, with a focus on reports in the last three years and are categorized into three subjects: (1) thermal management technologies of a passive type using light irradiation of the outside environment (photothermal heating), (2) those of an active type employing external electrical circuits (Joule heating), and (3) biomimetic structures. Fibers and textiles from the design of fibers and textiles perspective are also discussed with suggestions for future directions to maximize thermal storage and to minimize heat loss.

Physical drug delivery enhancement for aged skin, UV damaged skin and skin cancer: Translation and commercialization

This review analyses physical drug delivery enhancement technologies with a focus on improving UV damaged skin, actinic keratoses and non-melanoma skin cancer treatment. In recent years, physical drug delivery enhancement has been shown to enhance cosmeceutical and skin cancer treatment efficacy, but there are pros and cons to each approach which we discuss in detail. Mechanisms of action, clinical efficacy, experimental design, outcomes in academic publications, clinical trial reports and patents are explored to evaluate each technology with a critical, translation focused lens. We conclude that the commercial success of cosmeceutical applications, e.g. microneedles, will drive further innovation in this arena that will impact how actinic keratoses and non-melanoma skin cancers are clinically managed.

Thermoresponsive gating membranes embedded with liquid crystal(s) for pulsatile transdermal drug delivery: An overview and perspectives

Due to the circadian rhythm regulation of almost every biological process in the human body, physiological and biochemical conditions vary considerably over the course of a 24-h period. Thus, optimal drug delivery and therapy should be effectively controlled to achieve the desired therapeutic plasma concentrations and therapeutic drug responses at the required time according to chronopharmacological concepts, rather than continuous maintenance of constant drug concentrations for an extended time period. For many drugs, it is not always necessary to constantly deliver a drug into the human body under disease conditions due to rhythmic variations. Pulsatile drug delivery systems (PDDSs) have been receiving more attention in pharmaceutical development by providing a predetermined lag period, followed by a fast or rate-controlled drug release after application. PDDSs are characterized by a programmed drug release, which may release a drug at repeatable pulses to match the biological and clinical needs of a given disease therapy. This review article focuses on thermoresponsive gating membranes embedded with liquid crystals (LCs) for transdermal drug delivery using PDDS technology. In addition, the principal rationale and the advanced approaches for the use of PDDSs, the marketed products of chronotherapeutic DDSs with pulsatile function designed by various PDDS technologies, pulsatile drug delivery designed with thermoresponsive polymers, challenges and opportunities of transdermal drug delivery, and novel approaches of LC systems for drug delivery are reviewed and discussed. A brief overview of all academic research articles concerning single LC- or binary LC-embedded thermoresponsive membranes with a switchable on-off permeation function through topical application by an external temperature control, which may modulate the dosing interval and administration time according to the therapeutic needs of the human body, is also compiled and presented. In the near future, since thermal-based approaches have become a well-accepted method to enhance transdermal delivery of different water-soluble drugs and macromolecules, a combination of the thermal-assisted approach with thermoresponsive LCs membranes will have the potential to improve PDDS applications but still poses a great challenge.

Advanced Approaches of Bioactive Peptide Molecules and Protein Drug Delivery Systems

Despite the fact that protein and peptide therapeutics are widely employed in the treatment of various diseases, their delivery is posing an unembellished challenge to the scientists. It was discovered that delivery of these therapeutic systems through oral route is easy with high patient compliance. However, proteolytic degradation and absorption through the mucosal epithelium are the barriers in this route. These issues can be minimized by the use of enzyme inhibitors, absorption enhancers, different carrier systems or either by direct modification. In the process of investigation, it was found that transdermal route is not posing any challenges of enzymatic degradation, but, still absorption is the limitation as the outer layer of skin acts as a barrier. To suppress the effect of the barrier and increase the rate of the absorption, various advanced technologies were developed, namely, microneedle technology, iontophoresis, electroporation, sonophoresis and biochemical enhancement. Indeed, even these molecules are targeted to the cells with the use of cell-penetrating peptides. In this review, delivery of the peptide and protein therapeutics using oral, transdermal and other routes is discussed in detail.

Transformation of the dermal collagen framework under laser heating

The aim of this study was to compare between the changes undergone by the dermal collagen framework when heated by IR laser radiation and by traditional means and to reveal the specific features of the dermal matrix modification under moderate IR laser irradiation. Rabbit skin specimens were heated to 50°C, 55°C, 60°C and 65°C in a calorimeter furnace and with a 1.68-μm fiber Raman laser. The proportion of the degraded collagen macromolecules was determined by differential scanning calorimetry. Changes in the architectonics of the collagen framework were revealed by using standard, phase-contrast, polarization optical and scanning electron microscopy techniques. The collagen denaturation and dermal matrix amorphization temperature in the case of laser heating proved to be lower by 10°C than that for heating in the calorimeter furnace. The IR laser treatment of the skin was found to cause a specific low-temperature (45°C-50°C) transformation of its collagen framework, with some collagen macromolecules remaining intact. The transformation reduces to the splitting of collagen bundles and distortion of the course of collagen fibers. The denaturation of collagen macromolecules in the case of traditional heating takes its course in a threshold manner, so that their pre-denaturation morphological changes are insignificant.

Development of tizanidine loaded aspasomes as transdermal delivery system: ex-vivo and in-vivo evaluation

New generation of amphiphilic vesicles known as aspasomes were investigated as potential carriers for transdermal delivery of tizanidine (TZN). Using full factorial design, an optimal formulation was developed by evaluating the effects of selected variables on the properties of the vesicles with regards to entrapment efficiency, vesicle size and cumulative percentage released. The optimal formula (TZN-AS 6) consisting of 20 mg TZN, 50 mg ascorbyl palmitate (AP), 50 mg cholesterol (CH) and 50 mg Span 60, represented well dispersed spherical vesicles in the nanorange sizes and exhibited excellent stability under different storage conditions. Ex-vivo permeation studies using excised rat skin showed a 4.4-fold increase of the steady state flux in comparison to the unformulated drug (p < 0.05). The pharmacokinetic parameters obtained from the in-vivo study using Wistar rats, showed that the bioavailability of TZN was enhanced significantly (p < 0.05) when compared to the oral market product of TZN, Sirdalud^®. Moreover, skin irritancy tests confirmed that the vesicles were non-invasive and safe for the skin. Based on the results obtained, the optimised aspasomes formula represents a promising Nano platform for TZN to be administered transdermally, thus improving the therapeutic efficacy of this important muscle relaxant.

Photothermal Polymer Nanocomposites of Tungsten Bronze Nanorods with Enhanced Tensile Elongation at Low Filler Contents

We present polymer nanocomposites of tungsten bronze nanorods (TBNRs) and ethylene propylene diene monomers (EPDM). The combination of these components allows the simultaneous enhancement in the mechanical and photothermal properties of the composites at low filler contents. The as-synthesized TBNRs had lengths and diameters of 14.0 ± 2.4 nm and 2.5 ± 0.5 nm, respectively, and were capped with oleylamine, which has a chemical structure similar to EPDM, making the TBNRs compatible with the bulk EPDM matrix. The TBNRs absorb a wide range of near-infrared light because of the sub-band transitions induced by alkali metal doping. Thus, the nanocomposites of TBNRs in EPDM showed enhanced photothermal properties owing to the light absorption and subsequent heat emission by the TBNRs. Noticeably, the nanocomposite with only 3 wt% TBNRs presented significantly enhanced tensile strain at break, in comparison with those of pristine EPDM, nanocomposites with 1 and 2 wt % TBNRs, and those with tungsten bronze nanoparticles, because of the alignment of the nanorods during tensile elongation. The photothermal and mechanical properties of these nanocomposites make them promising materials for various applications such as in fibers, foams, clothes with cold weather resistance, patches or mask-like films for efficient transdermal delivery upon heat generation, and photoresponsive surfaces for droplet transport by the thermocapillary effect in microfluidic devices and microengines.

Delivery of antiseptic solutions by a bacterial cellulose wound dressing: Uptake, release and antibacterial efficacy of octenidine and povidone-iodine

BACKGROUND

Bacterial nanocellulose (BNC) is considered a promising carrier for various substances and novel approaches using BNC in combination with antiseptics are well documented. However, the difference in the molecular weight of these molecules influences their uptake by and release from BNC. Analysing the diffusion of standard molecules with different weight, e.g. dextrans, offers the possibility to investigate the mobility of various molecules. We aimed to test the use of BNC regarding uptake and release of different standard molecules as well as two commercially available antiseptics for possible applications in future wound dressings.

MATERIAL AND METHODS

Diffusion profiles, uptake and release of three FITC-dextran molecules differing in weight as well as octenidine (Octenisept®) and povidone-iodine (Betaisodona®)-based antiseptics were tested with BNC-based wound dressings. Furthermore, the antiseptic efficacy of BNC in combination with antiseptics against Staphylococcus aureus was tested.

RESULTS

Uptake and release capacity for FITC-dextran molecules showed a molecular weight-dependent mobility from BNC into an agarose gel. The loading capacity of BNC was also inversely proportional to the molecular weight of the antiseptics. The release test for octenidine showed a sustained and prolonged delivery into a solid matrix, whereas povidone-iodine was released faster. Both antiseptic solutions combined with BNC showed a good dose-dependent efficacy against S. aureus.

CONCLUSION

Results obtained from the mobility of FITC-dextran molecules in the BNC matrix could open possible applications for the combination of BNC with other molecules for medical applications. Combination of both tested antiseptics with BNC showed to be an efficient approach to control bacterial infections.

Near-infrared light activatable hydrogels for metformin delivery

Drug loaded hydrogels have proven to be versatile controlled-release systems. We report here on heat active hydrogel formation by mixing graphene oxide (GO) or carboxyl enriched reduced graphene oxide (rGO-COOH) with metformin hydrochloride, an insulin sensitizer drug currently used as the first line therapy to treat patients with type 2 diabetes. The driving forces of the gelation process between the graphene-based nanomaterial and metformin are hydrogen bonding and electrostatic interactions, weakened at elevated temperature. Using the excellent photothermal properties of the graphene matrixes, we demonstrate that these supramolecular drug reservoirs can be photothermally activated for transdermal metformin delivery. A sustained delivery of metformin was achieved using a laser power of 1 W cm-2. In vitro assessment of the key target Glucose-6 Phosphatase (G6P) gene expression using a human hepatocyte model confirmed that metformin activity was unaffected by photothermal activation. In vivo, metformin was detected in mice plasma at 1 h post-activation of the metformin loaded rGO-COOH gel.

Preferential Accumulation of Phospholipid-PEG and Cholesterol-PEG Decorated Gold Nanorods into Human Skin Layers and Their Photothermal-Based Antibacterial Activity

Herein, a library of gold nanorods (GNR) decorated with polyethylene glycol-thiol (PEG-SH) containing different functionalities were synthesized and characterized by optical absorption spectroscopy, zeta potential, dynamic light scattering (DLS), transmission electron microscope (TEM) and proton nuclear magnetic resonance (1H-NMR). The colloidal stability of GNR when exposed to skin, and their preferential accumulation into excised human skin layers were investigated. Confocal laser scanning microscopy, transmission electron microscope (TEM) and inductively coupled plasma-optical emission spectroscopy (ICP-OES) were utilized to track the penetration of GNR into different skin layers. The results demonstrated that cholesterol-PEG coated GNR were preferentially loaded up in the upper layers of skin (stratum corneum), while phospholipid-PEG coated counterparts were drastically deposited in skin dermis. Neutral methoxy-PEG-coated GNR were distributed in both SC and dermis skin layers, while charged GNR (anionic-carboxylic acid-PEG-GNR and cationic-amine-PEG-GNR) revealed a minimal accumulation into skin. DSPE-PEG-GNR and Chol-PEG-GNR demonstrated antibacterial activities against Staphylococcus aureus (S aureus) at MIC values of 0.011 nM and 0.75 nM, respectively. Photothermal treatment for S. aureus at sub-MIC concentrations resulted in a significant bactericidal effect when using Chol-PEG-GNR but not DSPE-PEG-GNR. Gold-based nanoscale systems have great value as a promising platform for skin diseases therapy.

Self-Nanoemulsifying Electrospun Fiber Enhancing Drug Permeation

Electrospun fibers are excellent drug carriers and tissue engineering scaffolds. However, approaches to promote drug permeation in tissues with such carriers remain of great interest. Here, we propose a Quality-by-Design strategy to enhance drug permeation with self-nanoemulsifying electrospun fibers. Owing to the nanoemulsion which formed spontaneously when the polymer contacts aqueous solution such as body fluid, the resulting drug-laden fibrous membrane exhibits an outstanding drug permeation and therapeutic enhancement effect in a Franz cell experiment with ex vivo abdomen skin of rats, an artificial connective tissue model, and an in vivo rheumatoid arthritis model in rats. Meanwhile, the material also shows the capacity of rational regulation on the rate of drug release. These features of the present strategy establish our material as a new efficient approach for various clinical conditions calling for cure.

Nanoformulations of doxorubicin: how far have we come and where do we go from here?

Nanotechnology, focused on discovery and development of new pharmaceutical products is known as nanopharmacology, and one research area this branch is engaged in are nanopharmaceuticals. The importance of being nano has been particularly emphasized in scientific areas dealing with nanomedicine and nanopharmaceuticals. Nanopharmaceuticals, their routes of administration, obstacles and solutions concerning their improved application and enhanced efficacy have been briefly yet comprehensively described. Cancer is one of the leading causes of death worldwide and evergrowing number of scientific research on the topic only confirms that the needs have not been completed yet and that there is a wide platform for improvement. This is undoubtedly true for nanoformulations of an anticancer drug doxorubicin, where various nanocarrriers were given an important role to reduce the drug toxicity, while the efficacy of the drug was supposed to be retained or preferably enhanced. Therefore, we present an interdisciplinary comprehensive overview of interdisciplinary nature on nanopharmaceuticals based on doxorubicin and its nanoformulations with valuable information concerning trends, obstacles and prospective of nanopharmaceuticals development, mode of activity of sole drug doxorubicin and its nanoformulations based on different nanocarriers, their brief descriptions of biological activity through assessing in vitro and in vivo behavior.