Skin Application Research Articles

Design and Characterization of an Ethosomal Gel Encapsulating Rosehip Extract

Rising environmental awareness drives green consumers to purchase sustainable cosmetics based on natural bioactive compounds. The aim of this study was to deliver Rosa canina L. extract as a botanical ingredient in an anti-aging gel using an eco-friendly approach. Rosehip extract was first characterized in terms of its antioxidant activity through a DPPH assay and ROS reduction test and then encapsulated in ethosomal vesicles with different percentages of ethanol. All formulations were characterized in terms of size, polydispersity, zeta potential, and entrapment efficiency. Release and skin penetration/permeation data were obtained through in vitro studies, and cell viability was assessed using an MTT assay on WS1 fibroblasts. Finally, ethosomes were incorporated in hyaluronic gels (1% or 2% w/v) to facilitate skin application, and rheological properties were studied. Rosehip extract (1 mg/mL) revealed a high antioxidant activity and was successfully encapsulated in ethosomes containing 30% ethanol, having small sizes (225.4 ± 7.0 nm), low polydispersity (0.26 ± 0.02), and good entrapment efficiency (93.41 ± 5.30%). This formulation incorporated in a hyaluronic gel 1% w/v showed an optimal pH for skin application (5.6 ± 0.2), good spreadability, and stability over 60 days at 4 °C. Considering sustainable ingredients and eco-friendly manufacturing technology, the ethosomal gel of rosehip extract could be an innovative and green anti-aging skincare product.

Plaster Gel Loaded with Silver Nanoparticle-Mediated Ganoderma applanatum: from Fabrication to Evaluation.

Traditional Asian remedies have mainly employed the macrofungus Ganoderma applanatum, which belongs to the family Ganodermataceae, as a medicinal mushroom due to its high antibacterial and antioxidant activity. Extracts of the fungus can be synthesized into nanoparticles, which are subsequently produced as plaster gels. Synthesized silver nanoparticle-mediated G. applanatum was discovered to have the greatest ability to inhibit bacterial growth in S. epidermidis. When applied to the skin, the prepared plaster gel converted from a gel to a film; thus, both gel and film generation are characteristic of its formulation. The plaster gel that was made was found to be consistent and attractive, and the yellow color had darkened. Its viscosity and pH were appropriate for the application and allowed it to remain on the skin without dripping or reacting with the skin until it dried. A shorter duration for film formation is possible. The film's tensile was slightly reduced, and it exhibited excellent thermal stability. Decomposition of the generated film occurred at a slower rate, which constrained the polymer chain's ability to move. The semi-crystalline structure was characteristic of the film. It was found that particles were distributed in the film. Rapid release from plaster gel within 4h was seen, and this was followed by a period of a slowly declining release rate over 12h. The accurate first-order kinetic used to estimate the release rate of the formulation. The plaster gel demonstrated greater antibacterial activity than the MIC value indicated. The in vivo evaluation was positive and showed no skin irritation. The formulation showed good stability. Therefore, this indicated that the prepared plaster gel is appropriate for topical pharmaceutical delivery and safe for skin application.

A Lightweight Swin Transformer-Based Pipeline for Optical Coherence Tomography Image Denoising in Skin Application

Optical coherence tomography (OCT) has attracted attention in dermatology applications for skin disease characterization and diagnosis because it provides high-resolution (<10 μm) of tissue non-invasively with high imaging speed (2–8 s). However, the quality of OCT images can be significantly degraded by speckle noise, which results from light waves scattering in multiple directions. This noise can hinder the accuracy of disease diagnosis, and the conventional frame averaging method requires multiple repeated (e.g., four to six) scans, which is time consuming and introduces motion artifacts. To overcome these limitations, we proposed a lightweight U-shape Swin (LUSwin) transformer-based denoising pipeline to recover high-quality OCT images from the noisy OCT images by utilizing a fast one-repeated OCT scan. In terms of the peak signal-to-noise-ratio (PSNR) performance, the results reveal that the denoised images from the LUSwin transformer (26.92) are of a higher quality than the four-repeated frame-averaging method (26.19). Compared to the state-of-the-art networks in image denoising, the proposed LUSwin transformer has the smallest floating points operation (3.9299 G) and has the second highest PSNR results, only 0.02 lower than the Swin-UNet, which has the highest PSNR results (26.94). This study demonstrates that the transformer model has the capacity to denoise the noisy OCT image from a fast one-repeated OCT scan.

Active-passive compound metasurface for simultaneously manipulating radiation and scattering in a wide band

Metasurfaces, which are usually passive or non-radiating, have provided unprecedented degree of freedom especially for scattering manipulation. For the manipulating radiation, metasurfaces often serve as auxiliaries to radiators since they cannot radiate themselves. Thus, it is unfavorable for integration and miniaturization. In this work, we propose the concept of active–passive compound metasurface (APCM) and explore the possibility of utilizing meta-atoms as active radiators, so as to simultaneously achieve flexible radiation and scattering manipulations at the same time. To this end, a meta-atom structure with large reflection phase-span is delicately designed. In this way, the meta-atom can serve both as wideband radiator fed by a probe and reflection-phase modulator. Flexible scattering-pattern manipulation for one polarization state and high-efficiency radiation-pattern manipulation for the orthogonal polarization state can be simultaneously achieved within the same band from 8.0 to 12.0 GHz. As a proof of concept, two prototypes, one for scattering-cancellation and high-directive radiation while the other for deflected reflection and vortex-beam radiation, were designed, fabricated, and measured, respectively. Both the simulated and measured results verify the active–passive compound design. This work paves an alternative route to integrated multi-functional materials or interfaces and may find wide applications in next-generation communication, radar, smart skin, and others.

An ionic pressure sensor array with digitizable sensitivity

Flexible pressure sensors play an indispensable role in electronic skin. A flexible pressure sensor array with a larger sensing area is an inevitable trend for further developing a single flexible pressure sensor. However, pressure sensor arrays suffer from a key challenge: each sensing unit in the array cannot be individually defined for its pressure sensing range and sensitivity. Here, we present an ionic pressure sensor array with digitizable sensitivity achieved through the synergistic cooperation of an ion gel shell interfacial capacitive sensing mechanism and a filler with digitally tunable mechanical stiffness. Through this design, the sensitivity of each sensing pixel unit in the array can be digitally defined in the range of 20 times, and the fabrication process is greatly simplified. We fabricated sensor arrays for object contour recognition and weight judgment, demonstrating their potential application in electronic skin. In addition, we proposed using a customized 3D printer of elastomer to simplify its fabrication process, which is beneficial for engineering applications.

Transient Receptor Potential Channel Vanilloid 1 Contributes to Facial Mechanical Hypersensitivity in a Mouse Model of Atopic Asthma

Sensitive skin, a common pathophysiological feature of allergic diseases, is defined as an unpleasant sensation in response to stimuli that normally should not provoke such sensations. However, the relationship between allergic inflammation and hypersensitive skin in the trigeminal system remains to be elucidated. To explore whether bronchial allergic inflammation affects facial skin and primary sensory neurons, we used an ovalbumin (OVA)–induced asthma mouse model. Significant mechanical hypersensitivity was observed in the facial skin of mice with pulmonary inflammation induced by OVA sensitization compared to mice treated with adjuvant or vehicle as controls. The skin of OVA-treated mice showed an increased number of nerve fibers, especially rich intraepithelial nerves, compared to controls. Transient receptor potential channel vanilloid 1 (TRPV1)–immunoreactive nerves were enriched in the skin of OVA-treated mice. Moreover, epithelial TRPV1 expression was higher in OVA-treated mice than in controls. Trigeminal ganglia of OVA-treated mice displayed larger numbers of activated microglia/macrophages and satellite glia. In addition, more TRPV1 immunoreactive neurons were found in the trigeminal ganglia of OVA-treated mice than in controls. Mechanical hypersensitivity was suppressed in OVA-treated Trpv1-deficient mice, while topical skin application of a TRPV1 antagonist before behavioral testing reduced the reaction induced by mechanical stimulation. Our findings reveal that mice with allergic inflammation of the bronchi had mechanical hypersensitivity in the facial skin that may have resulted from TRPV1-mediated neuronal plasticity and glial activation in the trigeminal ganglion.

Application of a novel multicomponent nanoemulsion to tumor therapy Based on the theory of “unification of drugs and excipients”

Toad skin has many pharmacological activities and bufadienolides are regarded as its main anti-tumor components. The poor water solubility, high toxicity, rapid elimination and less selectivity in vivo of bufadienolides limit the application of toad skin. Based on the “unification of drugs and excipients” theory, the toad skin extracts (TSE) and Brucea javanica oil (BJO) nanoemulsions (NEs) were designed to solve the aforementioned problems. BJO as the main oil phase was not only used to prepare the NEs, but played a synergistic therapeutic role combined with TSE. TSE-BJO NEs showed 155 nm particle size, entrapment efficiency of >95% and good stability. TSE-BJO NEs demonstrated superior anti-tumor activity compared with the TSE or BJO NEs alone. The mechanism of TSE-BJO NEs to enhance the antineoplastic efficacy involved several pathways, such as inhibiting cell proliferation, inducing tumor cell apoptosis >40% and arresting cell cycle at G2/M. TSE-BJO NEs could co-deliver drugs into the target cells efficiently and exhibit satisfying synergism. Besides, TSE-BJO NEs facilitated the long circulation of bufadienolides contributing to the high accumulation of drugs at tumor sites and the improvement of anti-tumor efficacy. The study achieves the combinative administration of the toxic TSE and BJO with high efficacy and safety.

Stretchable and All-Directional Strain-Insensitive Electronic Glove for Robotic Skins and Human-Machine Interfacing.

Electronic gloves (e-gloves), with their multifunctional sensing capability, hold a promising application in robotic skin and human-machine interfaces, endowing robots with a human sense of touch. Despite the progress in developing e-gloves by exploiting flexible or stretchable sensors, existing models have inherent rigidity in their sensing area, limiting their stretchability and sensing performance. Herein, we present an all-directional strain-insensitive stretchable e-glove that successfully extends sensing functionality such as pressure, temperature, humidity, and ECG with minimal crosstalk. A scalable and facile method is successfully demonstrated by combining low-cost CO2 laser engraving and electrospinning technology to fabricate multimodal e-glove sensors with a vertical architecture. In comparison to other smart gloves, the proposed e-glove features a ripple-like meandering sensing area and interconnections that are designed to stretch in response to the applied deformation, without affecting the performance of the sensors offering full mechanical stretchability. Furthermore, CNT-coated laser-engraved graphene (CNT/LEG) is used as an active sensing material in which the cross-linking network of the CNT in the LEG minimizes the stress effect and maximizes the sensitivity of the sensors. The fabricated e-glove can detect hot/cold, moisture, and pain simultaneously and precisely, while also allowing for remote transmission of sensory data to the user.

The effect of long skin soaking in the calcium solution on the quality of rambak crackers from buffalo skin

Buffalo skin is an underutilized by-product of buffalo slaughter. It is perishable and if it is not processed immediately, it will rot. One of the applications of buffalo skin is processing into skin crackers. The present research was aimed at determining the best duration of buffalo skin soaking in the lime solution with regard to its effect on quality of rambak from buffalo skin. The study used a completely randomized design (CRD) with a factor of treatment time, which consisted of four levels, i.e. A=76 hours, B=86 hours, C=96 hours, D=106 hours. Each treatment was performed with five replicates, so that 20 samples were obtained. The data were analyzed using the statistical analysis of variance (ANOVA). Parameters observed were the water content, yield, volume expansion, and organoleptic characteristics such as taste, aroma, color, and texture. The results show that different soaking duration (76 hours, 86 hours, 96 hours, and 106 hours) did not have a significant effect on yield, taste, aroma, color, and texture, but significantly affected the volume expansion and water content in rambak from buffalo skin. The best result was achieved with soaking duration of 106 hours; the rambak was characterized by the following parameters: water content 10.83%, yield 57.87%, volume expansion 76.66%, color score 3.51, taste score 3.61, aroma score 3.63 and texture score 3.30.

Low-Intensity Visible and Near-Infrared Light-Induced Cell Signaling Pathways in the Skin: A Comprehensive Review

Objective: To describe current knowledge regarding established and putative cell signaling pathways involved in skin photobiomodulation. Background: The skin is the largest and most accessible organ of the body. It is the first line of defense against the external environment, including solar radiation. Among solar rays, visible and infrared non-ionizing photons may reach human skin and trigger a cascade of non-thermal cell signaling pathways called photobiomodulation (PBM). The use of PBM using artificial light sources has been known for more than 50 years, but it has not yet been widely accepted due to uncertainty about the cellular mechanisms of action. However, much knowledge has been gained in this field in recent years, which will be summarized in this review. Methods: An extensive literature review was performed using Medline, Embase, and Google Scholar as research databases to acquire relevant publications in this particular field. Results: A comprehensive description of chromophores, primary and secondary effectors is provided in addition to a visual representation of known and putative cell signaling mechanisms involved in such complex light-skin interactions. Also, a summary of clinical indications of skin PBM, key light parameters, and promising skin applications (local and systemic) are mentioned. Conclusions: In PBM, skin cells are the first to absorb photons, triggering specific cell-signaling pathways through primary and secondary effectors, leading to enhanced cell repair and survival, notably in hypoxic or stressed cells. A better understanding of the mechanisms of action will help us optimize known indications and discover new ones.

75Se - A promising alternative to 192Ir for potential use in the skin cancer brachytherapy: A Monte Carlo simulation study using FLUKA code

This study aimed to evaluate the possibility of utilizing the HDR 75Se source for skin cancer brachytherapy. In this work, based on the BVH-20 skin applicator, two cup-shaped applicators, without and with the flattening filter, were modeled. To obtain the optimal flattening filter shape, an approach based on the MC simulation in combination with an analytical estimation was used. Then, the dose distributions for 75Se-applicators were generated using MC simulations in water, and their dosimetric characterizations such as flatness, symmetry, and penumbra were evaluated. Furthermore, the radiation leakage in the backside of the applicators was estimated by additional MC simulation. Finally, to evaluate the treatment times, calculations were performed for two 75Se-applicators assuming 5 Gy per fraction. The flatness, symmetry, and penumbra values for the 75Se-applicator without the flattening filter were estimated to be 13.7%, 1.05, and 0.41 cm respectively. The corresponding values for 75Se-applicator with the flattening filter were estimated to be 1.6%, 1.06, and 0.10 cm respectively. The radiation leakage value at a distance of 2 cm from the applicator surface was calculated to be 0.2% and 0.4% for the 75Se-applicator without and with the flattening filter respectively. Our results showed that the treatment time for the 75Se-applicator is comparable with that of the 192Ir-Leipzig applicator. The findings revealed that the dosimetric parameters of the 75Se applicator are comparable with the 192Ir skin applicator. Overall, the 75Se source can be an alternative to 192Ir sources for HDR brachytherapy of skin cancer.

Skin Improvement of the Composition Containing Nano-exosome Derived from Aloe vera Bark Callus as New Type of Transdermal Delivery System

Purpose: The purpose of this study was to extract nano-exosomes from Aloe vera bark callus and validate their effects on collagen synthesis and skin corneous improvement.Methods: Human dermal fibroblast (HDF) was used to validate collagen synthesis, while HaCaT cells, a human keratin cell line, were used to verify absorption capability. The Folin–Denis technique was used to determine the polyphenol content. In addition, lotion formulations and skin application experiments were also carried out.Results: Nano-exosomes with size ranging 50–150 nm were successfully isolated from Aloe vera bark callus (alosomes). Alosomes produced 22.11% more collagen in HDF than Aloe vera bark extract at 1.0% concentration. In the cytotoxicity test, 80% of cells were survived at concentrations of 1% or less. After one hour, a considerable quantity was transported into the cytoplasm of HaCaT cells. The polyphenol concentration was four times that of Aloe vera bark extract. Skin tests using alosome-containing lotion demonstrated that skin surface, hydration, and elasticity were improved after 4 weeks. Moisture contents of the stratum corneum and dermis layer were improved, whereas moisture content of corneous was reduced after 4 weeks.Conclusion: The skin-improving effect of nano-exosomes derived from Aloe vera bark callus is shown in this study, indicating its potential as a functional cosmetic raw material.

Norcantharidin Nanoemulsion Development, Characterization, and In Vitro Antiproliferation Effect on B16F1 Melanoma Cells.

Melanoma is a highly lethal type of cancer that has had an increase in incidence in the last decades. Nevertheless, current therapies lack effectiveness and have highly disabling side effects, which calls for new therapeutic strategies. Norcantharidin (NCTD) is an acid derivative with potential antitumor activity isolated from natural blister beetles. However, its solubility limitations restrict its use. To address this issue, we developed an oil-in-water nanoemulsion using commonly available cosmetic ingredients, which increased NCTD solubility 10-fold compared to water. The developed nanoemulsion showed a good droplet size and homogeneity, with adequate pH and viscosity for skin application. In vitro drug release studies showed a sustained release profile, ideal for prolonged therapeutic effects. Accelerated stability studies proved that the formulation was reasonably stable under stress conditions, with particle separation fingerprints, instability index, particle size, and sedimentation velocity analyses being conducted. To assess the therapeutic potential of the developed formulation, in vitro studies were conducted on melanoma B16F1 cells; results showed an IC50 of 1.026 +/- 0.370 mg/kg, and the cells' metabolic activity decreased after exposure to the NCTD nanoemulsion. Hence, a new "easy-to-make" nanoformulation with therapeutic potential on melanoma cells was developed, as a possible adjuvant for future melanoma treatment.

Исследование переносимости препарата БАРС® капли инсектоакарицидные для кошек

Ectoparasites are a serious problem for veterinarians and pet owners.
 Insectoacaricidal preparation BARS®, developed by NVC Agrovetzashchita LLC, is a multicomponent insectoacaricide and is produced in the form of drops at the withers. For cats as active substances in 1 ml contains: fipronil ‒ 100 mg, cyfluthrin ‒ 2.5 mg, piperonyl butoxide ‒ 0.5 mg, diflubenzuron ‒ 1 mg.
 Purpose of the study. To study the tolerability of the drug during its repeated use in cats at a therapeutic dose of 0.5 ml/5 kg and a double therapeutic dose of 1 ml/5 kg of body weight with daily skin application for 7 days.
 
 Materials and methods. To study the tolerability of the Insectoacaricidal preparation BARS®, 3 groups of cats were formed, 10 animals each (2 experimental and 1 control).
 Results. During the experiment, there were no external signs of intoxication in cats. All animals of the experimental groups were active. The reaction to external stimuli is preserved. The body temperature of the animals throughout the experiment remained within the physiological range in all groups.
 Conclusion. The drug in recommended doses is well tolerated by cats, does not adversely affect the general physiological state, morphological and biochemical parameters of blood, and physical and chemical parameters of urine. Also, they do not have a skin-resorptive and locally irritating effect.

AuCu decorated MXene/RGO aerogels towards wearable thermal management and pressure sensing applications

MXene based aerogels with efficient thermal insulation, excellent electrical conductivity, reversible compressibility, and high durability hold great potential for various applications, ranging from wearable electronics to multifunctional scaffolds. How to balance various performance to adapt to more application scenarios is an urgent problem to be solved. In the present work, honeycomb AuCu alloy nanoparticles decorated Ti3C2Tx MXene/RGO aerogels (MXene/RGO/AuCu NPs aerogels) were prepared by a simple reduction and directional freeze-drying method. The optimized MXene/RGO/AuCu NPs aerogels have low density (0.023 g/cm3), flame retardant, robust mechanical properties (longitudinal and transverse compressive modulus of 450.9 kPa and 79.9 kPa at 90% strain, respectively) and 80% compressive elasticity. The deformable porous structure enables it to respond to pressure, which has been proved to be applied to pulse and human respiration monitoring. The ordered pore structure and the LSPR effect of MXene and AuCu particles make aerogels have heat resistance, flame retardancy, good electrothermal (can rise to 245.2 °C in 6 s at 7 V drive voltage) and photothermal properties (109 °C in 10 s at 1sun sunlight intensity). The excellent thermal management capability and pressure sensing characteristics make it a prospect application in wearable flexible heaters and artificial skin.

Simultaneous Polymerization Acceleration and Mechanical Enhancement for Printing a Biomimetic PEDOT Adhesive by Coordinative and Orthogonal Ruthenium Photochemistry

Conductive hydrogels are promising material candidates in fields ranging from flexible sensors and electronic skin applications to personalized medical monitoring. However, developing intrinsically conductive polymer hydrogels (ICPHs) with high mechanical properties and excellent printability is still challenging. Here, we introduce a simultaneous polymerization acceleration and mechanical enhancement (SPAME) strategy to construct PEDOT-based ICPHs via the rational design of coordinative and orthogonal ruthenium photochemistry (CORP). This orthogonal photochemistry triggers the oxidative polymerization of EDOT and the coupling of phenols within seconds under blue light irradiation. Benefiting from the bifunctional EDTA-Fe design, the photoreleased Fe(III) accelerated the EDOT polymerization and shortened the preparation time of ICPHs to a few seconds. At the same time, the addition of EDTA-Fe enhanced their mechanical properties, and both the critical strains and maximum stresses of the hydrogel doubled. Furthermore, the introduction of phenol residues in PAA-Ph significantly shortened the gelation time from several minutes to about 7 s. Thus, this fast and controllable CORP chemistry is compatible with standard printing techniques for engineering hydrogels for complex multifunctional structures for multifunctional bioelectronics and devices.

In vitro anti-ageing activities of ethanolic extracts from Pink rambutan (Nephelium lappaceum Linn.) for skin applications

Skin ageing is characterized by features such as wrinkles, loss of elasticity, laxity, rough-textured appearance, melasma and freckles. Several researches have focused for preventing, and treating skin ageing by many natural ingredients. This study aimed to assess the anti-ageing activities for anti-skin ageing of the ethanolic extracts of Pink rambutan (PR) (Nephelium lappaceum Linn.) from leaves (L), branches (B), seeds (S), and peels from ripe (R) and young (Y) fruits. The extraction yields of all Pink Rambutan (PR) extracted by the Maceration (M) and the Soxhlet extraction (Sox) using 95% ethanol as a solvent, ranged from 10.62% to 30.63%. Flavonoids were found as the main phytochemicals in almost all the PR extracts. The PR-Y-M and PR-Y-Sox extracts gave the highest total phenolic contents by the Folin-Ciocalteu assay of 67.60 ± 4.38 mgGAE/g, and total flavonoid contents by the modified aluminum chloride colorimetric assay of 678.72 ± 23.59 mgQE/g, respectively. The PR-L-M extracts showed the highest three anti-oxidative activities; the free radical scavenging (SC50 of 0.320 ± 0.070 mg/mL), the lipid peroxidation inhibition (LC50 of 0.274 ± 0.029 mg/mL), and the metal chelation activity (MC50 of 0.203 ± 0.021 mg/mL). All the PR extracts at 0.01 and 0.1 mg/mL showed no cytotoxicity on B16F10 cells, and human skin fibroblasts, respectively. Likewise, the PR-R-Sox extract exhibited the highest anti-melanogenesis on B16F10 cells (52.7 ± 0.9%) and, the mushroom tyrosinase inhibition activity (IC50 of 0.04 ± 0.02 mg/mL), which was significantly comparable to kojic acid (p < 0.05). The PR-Y-Sox extract showed the collagen biosynthesis by the Sirius Red method, and the stimulation of anti-ageing genes (Sirt1 and Foxo1) on human skin fibroblasts by the RT-PCR method, which were similar to standards ʟ-ascorbic acid and resveratrol, respectively. This study suggests that the PR-R-Sox and PR-Y-Sox extracts can be further developed as natural anti-ageing agents for whitening and anti-wrinkle in the cosmetics, cosmeceutical, and pharmaceutical industries.

A Safe-by-Design Approach for the Synthesis of a Novel Cross-Linked Hyaluronic Acid with Improved Biological and Physical Properties.

Hyaluronic acid (HA) is a polymer with unique biological properties that has gained in interest over the years, with applications in pharmaceutical, cosmetic, and biomedical fields; however, its widespread use has been limited by its short half-life. Therefore, a new cross-linked hyaluronic acid was designed and characterized using a natural and safe cross-linking agent, such as arginine methyl ester, which provided improved resistance to enzymatic action, as compared to the corresponding linear polymer. The antibacterial profile of the new derivative was shown to be effective against S. aureus and P. acnes, making it a promising candidate for use in cosmetic formulations and skin applications. Its effect on S. pneumoniae, combined with its excellent tolerability profile on lung cells, also makes this new product suitable for applications involving the respiratory tract.

Unconventional and conventional Pickering emulsions: Perspectives and challenges in skin applications

Pickering emulsions are free from molecular and classical surfactants and are stabilized by solid particles, creating long-term stability against emulsion coalescence. Additionally, these emulsions are both environmentally and skin-friendly, creating new and unexplored sensorial perceptions. Although the literature mostly describes conventional emulsions (oil-in-water), there are unconventional emulsions (multiple, oil-in-oil and water-in-water) with excellent prospects and challenges in skin application as oil-free systems, permeation enhancers and topical drug delivery agents, with various possibilities in pharmaceutical and cosmetic products. However, up to now, these conventional and unconventional Pickering emulsions are not yet available as commercial products. This review brings to the discussion some important aspects such as the use of phases, particles, rheological and sensorial perception, as well as current trends in the development of these emulsions.

Environment-tolerant versatile ion-conductive eutectic hydrogels for self-powered wearable flexible sensors

Conductive hydrogels (CHs) have been widely utilized in the design of wearable flexible sensors. The remaining issues with CHs include their propensity to dehydrate in the open air and freeze at low temperatures, which makes them significantly less functional. Additionally, the wide applications of CHs are limited by their dependence on external power sources and inadequate sensing of humidity, strain, etc. Herein, a series of versatile ion-conductive adhesive hydrogels (GAAAD) with emblematic on-demand 3D cross-network structures were nanoengineered by combining solvent exchange strategies with in-situ physical and covalent cross-linking. The GAAAD possesses exceptional properties such as integrated outstanding sensing of multiple external stimuli in harsh environments, desirable adhesive ability towards various substrates, mechanical robustness, transparency, anti-freezing and anti-dehydration performance, and self-healing capacity. Even after being frozen at −20 ℃ for 48 h, GAAAD could be utilized for effective real-time human sleeping monitoring, demonstrating preponderant environmental stability. Integrated with the versatile origins of GAAAD, a simple Cu/GAAAD/Zn self-powered flexible sensor (GAAADB) was developed based on the fundamental structure of a primary battery, which exhibits remarkable properties of stable open-circuit voltage even in extremely cold environments, sensitive response to applied tensile or compressive strain, as well as its repeatability and durability. Interestingly, based on the sensing mechanism of the potential difference between the humidity-regulating electrodes, GAAADB was substantiated to be reliable for long-term respiratory monitoring (with the humidity response/recovery time less than 1 s) under extreme cold conditions (−20 °C), indicating its great potential for extensive applications in respiratory diagnosis, sleep monitoring, electronic skin, and wearable electronics.