Interactions between surfactants and the skin - Theory and practice

Exploring Bovine Serum Albumin (BSA) as a Facile Substrate for Testing of Osmolytes as Cosmetic Ingredients

Osmolytes, cellular compounds that maintain osmotic balance and integrity, are gaining attention in cosmetics for their ability to modulate protein folding and stability. Their incorporation into hair and skin care products enhances hydration and strengthens cellular structures. As the cosmetic industry seeks innovative and effective ingredients, osmolytes remain promising candidates for further advancing technologies. This study evaluates the protective effects of four osmolytes-betaine, erythritol, glycine, and isopentyldiol-on bovine serum albumin (BSA), as a substrate, under stressors such as UV irradiation, extreme temperatures, pH changes, surfactants, and oxidative stress. Protein stability was assessed via fluorescence emission. Only betaine at 0.50% w/w provided significant protection under oxidative stress, while glycine was the most effective osmolyte under basic and acidic pH and UVC radiation. Betaine showed potential in mitigating cold-induced stress but increased stress under UVA radiation, highlighting its condition-specific effects. The study emphasizes the need for comprehensive screening and synergistic testing of osmolytes to optimize cosmetic formulations for diverse stressors. Among the tested osmolytes, glycine is a promising candidate for skin and hair care products, though further research is needed. These findings provide a rapid, cost-effective method to evaluate osmolytes' potential, offering valuable insights for cosmetic formulation.

A review of the key ingredients in industrial formulations of baby wet wipes

The skin of newborns is classified as sensitive, with a higher risk of skin barrier disruption and irritation of a diapered area. Despite dermatologist recommendations to use only water and a cloth for cleaning, most of the population still relies on the comforts of modern parenting, which includes intensive daily usage of baby wet wipes. Novel baby formulations are designed following the concept of infant skin health, containing a gentle cleanser, suitable emollient, and buffer system enabling a slightly acidic pH value and they are free of ethyl alcohol. Thus, it is important to understand the chemical background of such a complex liquid formulation, with emphasis on its safety. In line with this, the present paper discusses the scientific background of various chemical compounds found in baby wipe formulations to improve the understanding of wet wipe designs and direct them toward more skin-friendly solutions.

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

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

Microscopic Origin of Surfactant Irritation: An Experimental and Computational Study

Surfactants, which are widely used in skin care products and cleansers, can cause skin irritation. The skin irritation potential of surfactants is fundamentally determined by their molecular structure and is directly related to their microscopic aggregation structure and specific interactions with the skin. The microscopic origin of the irritation of the surfactants remains unknown. In this work, irritation properties of four surfactant solutions were measured, and their microscopic aggregation behavior was systematically analyzed. The results indicate that the surfactants self-assembled in aqueous solution to form aggregates with different morphologies, where the head groups of surfactants were closer to each other. Furthermore, surfactants that can form larger and more stable aggregate structures in aqueous solutions will exhibit less irritation. These findings hold significant implications for the design and expanded applications of mild surfactants.

Panax notoginseng saponins loaded W/O microemulsion for alopecia therapy with panthenol as cosurfactant to reduce skin irritation

The etiology of alopecia is so complex that current therapies with single-mechanism and attendant side-effects during long-term usage, are insufficient for treatment. Panax notoginseng saponins (PNS) is supposed to treat alopecia with multiple mechanisms, but difficult to penetrate skin efficiently due to water-solubility. Here, we designed water-in-oil microemulsion (PNS ME) using jojoba oil, fractioned coconut oil, RH 40 + Span 80 and cosurfactant D-panthenol, to help PNS penetrating the skin. Particularly, D-panthenol not only enlarges the microemulsion area, reduces the usage amounts of surfactants thus relieves skin irritation, but stimulates the migration of dermal papilla cells (DPCs), displaying cooperative effects on anti-alopecia. PNS ME penetrates through sebum-rich corneum via high-affinity lipid fusion, targets to hair follicles (HFs), where it resides in skin for sustained drug release, accelerates angiogenesis to build well-nourished environment for HFs, and facilitates the proliferation and migration of DPCs in vitro. PNS ME markedly improved hair density, skin pigmentation, new hair weight, skin thickness, and collagen generation of telogen effluvium mice. Moreover, PNS also took outstanding curative effects on androgenetic alopecia mice. Upon further exploration, PNS ME caused dramatic upregulations of β-catenin, VEGF and Ki67, suggesting it might function by triggering Wnt/β-catenin pathway, accelerating vessels formation, and activating the hair follicle stem cells. Notably, PNS ME indicated longer-term safety than minoxidil tincture. Together, PNS ME provides a comprehensive strategy for alopecia, especially it avoids defects by high-proportioned surfactants in traditional microemulsion, exhibiting milder and safer, which shows bright prospect of applying microemulsion in hair growth promotion.

Choline-based ionic liquids enhance the dermal delivery of cyclosporine a for potential treatment of psoriasis

Psoriasis is a prevalent chronic disease affecting 2-3% of the global population. Cyclosporine A (CyA) has been widely used with great promise in the treatment of moderate to severe psoriasis despite various side effects associated with its systemic administration. Topical administration of CyA circumvents systemic side effects; however, the poor water solubility and large molecular weight of CyA pose challenges for dermal delivery. In this study, choline-based ionic liquids (ILs) were used to enhance the dermal delivery of CyA for the potential treatment of psoriasis. All four ILs tested significantly improved the solubility of CyA, which was greater than that of the control group with dimethyl sulfoxide (DMSO) as a solubilizer (20%, w/w). The saturated solubility of CyA in two of the ILs, choline geranate ([Ch][Ge]) and choline ricinoleate ([Ch][Ra]), reached more than 90 mg/mL, and the solubilization capability of the ILs except [Ch][Ci] was resistant to water dilution. The negligible change in CyA content determined by high-performance liquid chromatography and the secondary structure detected by circular dichroism spectroscopy confirmed the stability of CyA in the ILs. At 4 h in the in vitro penetration test, the amount of CyA retained in the skin in the IL groups was slightly greater than that in the control group (20% DMSO). The water content of the ILs significantly affected their penetration ability. When the water content increased from 10 to 70%, the dermal delivery of CyA first increased, peaked at a water content of 30%, and then decreased. The dermal delivery ability of [Ch][Ge] and [Ch][Ra] with a water content of 70% was still comparable to that of 20% DMSO. Moreover, CyA-loaded ILs (0.5%, w/w) significantly relieved the symptoms of psoriasis in an imiquimod (IMQ)-induced mouse model, and the levels of inflammatory factors, including tumor necrosis factor α, interleukin 22 and interleukin 17, in the affected area were reduced by 71.7%, 75.6%, and 89.3%, respectively. The IL tested, choline sorbate ([Ch][So]), showed low cytotoxicity to human immortalized epidermal cells (HaCaT). After 7 days of consecutive application, [Ch][So] did not cause significant irritation. In conclusion, ILs demonstrate promising potential for the dermal delivery of CyA for the treatment of psoriasis.

The Skin Acid Mantle: An Update on Skin pH

The acid mantle concept refers to the buffer system located in the upper stratum corneum of the skin. By sustaining an acidic environment, the acid mantle contributes to the regulation of the microbiome, structural stability, and inflammation. Skin pH is pivotal in maintaining the integrity of the epidermal barrier. Shifts in pH can disrupt barrier properties, and recent studies have emphasized its impact on dermatologic disease processes. This review explores the complex relationship of mechanisms through which skin pH impacts dermatologic pathologies. Furthermore, we highlight the promising potential of pH-targeted therapies for advancing the management of skin conditions.

Facile Preparation of Silica/Tannic Acid/Zein Microcapsules Templated from Non-Aqueous Pickering Emulsions and their Application in Cargo Protection

Microcapsules have attracted significant attention in academia and industry due to their unique properties for protecting and controlling the release of active substances. However, based on water-insoluble biopolymers, developing a straightforward approach to prepare microcapsules with improved biocompatibility and functional shells remains a great challenge. In this study, zein, a water-insoluble protein, is employed to prepare robust microcapsules facilely using oil-in-aqueous ethanol Pickering emulsions as templates. First, the emulsion template is stabilized by hydrophobic silica nanoparticles with in situ surface modification of tannic acid. The zein is then precipitated at the interface in a controlled manner using antisolvent approach to obtain silica/tannic acid/zein (STZ) microcapsules. It is found that the concentration of zein and the presence of tannic acid played a significant role in the formation of STZ microcapsules with well-defined morphology and a robust shell. The uniform deposition of zein on the surface of template droplets is facilitated by the interactions between tannic acid and zein via hydrogen bond and electrostatic force. Finally, the resulting STZ microcapsules showed super resistance to ultraviolet (UV) radiation and high temperature for the unstable, lipophilic, and active substance of β-carotene.

The riddle of response to cutaneous allergen exposure in patients with atopic dermatitis

The skin is the largest immunologic organ in the body and contains immune cells that play a role in both food allergen sensitization and desensitization. The dual allergen exposure hypothesis posits that sensitization to food allergens may occur with cutaneous exposure on inflamed skin, eg, atopic dermatitis, but early oral consumption generally leads to tolerance. However, only one-third of children with atopic dermatitis develop a food allergy, suggesting that there is a more complex mechanism for allergen sensitization. Emerging evidence suggests that the outcome of cutaneous allergen exposure is context-dependent and largely influenced by the state of the skin barrier with healthy skin promoting natural tolerance. Current research supports the ability to induce desensitization through repeated application of allergens to the skin, known as epicutaneous immunotherapy. Preclinical research with an occlusive patch has demonstrated a significantly reduced T-helper cell type 2-driven immunologic response when applied to intact, uninflamed skin and induction of a unique population of regulatory T cells that express a broader range of homing receptors, which may be able to maintain sustained protection. In clinical studies of children aged 1 through 11 years with a peanut allergy, epicutaneous immunotherapy with an occlusive patch led to significant desensitization with no major differences in efficacy or safety between children with and without atopic dermatitis. These data begin to answer the conundrum of how allergens that are applied to the skin can lead to both sensitization and desensitization, and future studies should enable us to optimize the power of the skin as a complex immunologic organ to treat allergic, autoimmune, and autoinflammatory disorders.

Exploring the biofilm inhibitory potential of Candida sp. UFSJ7A glycolipid on siliconized latex catheters

Biosurfactants, sustainable alternatives to petrochemical surfactants, are gaining attention for their potential in medical applications. This study focuses on producing, purifying, and characterizing a glycolipid biosurfactant from Candida sp. UFSJ7A, particularly for its application in biofilm prevention on siliconized latex catheter surfaces. The glycolipid was extracted and characterized, revealing a critical micellar concentration (CMC) of 0.98 mg/mL, indicating its efficiency at low concentrations. Its composition, confirmed through Fourier transform infrared spectroscopy (FT-IR) and thin layer chromatography (TLC), identified it as an anionic biosurfactant with a significant ionic charge of -14.8 mV. This anionic nature contributes to its biofilm prevention capabilities. The glycolipid showed a high emulsification index (E24) for toluene, gasoline, and soy oil and maintained stability under various pH and temperature conditions. Notably, its anti-adhesion activity against biofilms formed by Escherichia coli, Enterococcus faecalis, and Candida albicans was substantial. When siliconized latex catheter surfaces were preconditioned with 2 mg/mL of the glycolipid, biofilm formation was reduced by up to 97% for E. coli and C. albicans and 57% for E. faecalis. These results are particularly significant when compared to the efficacy of conventional surfactants like SDS, especially for E. coli and C. albicans. This study highlights glycolipids' potential as a biotechnological tool in reducing biofilm-associated infections on medical devices, demonstrating their promising applicability in healthcare settings.

Stimuli-Responsive Release-Active Dressing: A Promising Solution for Eradicating Biofilm-Mediated Wound Infections

Biofilm-mediated wound infections pose a significant challenge due to the limitations of conventional antibiotics, which often exhibit narrow-spectrum activity, fail to eliminate recurrent bacterial contamination, and are unable to penetrate the biofilm matrix. While the search for alternatives has explored the use of metal nanoparticles and synthetic biocides, these solutions often suffer from unintended toxicity to surrounding tissues and lack controlled administration and release. In this study, we engineered a pH-responsive release-active dressing film based on carboxymethyl cellulose, incorporating a synthetic antibacterial molecule (SAM-17). The dressing film exhibited optimal mechanical stability for easy application and demonstrated excellent fluid absorption properties, allowing for prolonged moisturization at the site of injury. The film exhibited pH-dependent release of cargo, with 78% release within 24 h at acidic pH, enabling targeted antibacterial drug delivery within the wound microenvironment. Furthermore, the release-active film effectively eliminated repeated challenges of bacterial contamination. Remarkably, the film demonstrated a minimal toxicity profile in both in vitro and in vivo models. The film eliminated preformed bacterial biofilms, achieving a reduction of 2.5 log against methicillin-resistant Staphylococcus aureus (MRSA) and 4.1 log against vancomycin-resistant S. aureus (VRSA). In a biofilm-mediated MRSA wound infection model, this release-active film eradicated the biofilm-embedded bacteria by over 99%, resulting in accelerated wound healing. These findings highlight the potential of this film as an effective candidate for tackling biofilm-associated wound infections.

Mild but effective skin cleansing-Evaluation of laureth-23 as a primary surfactant

OBJECTIVE

Skin cleansing products are among the main reasons for the development of hand eczema. Therefore, a mild but effective skin cleansing product is of particular interest, especially in the work place, where various contaminations frequently have to be removed from hands.

METHODS

In this study, the potential of laureth-23 as a primary surfactant was evaluated and compared to other fatty alcohol ethoxylates (FAEO). Also, different laureth-23 surfactant combinations were compared to each other. Therefore, transepidermal water loss, erythema and visual scoring were measured after occlusive patch testing in 24 healthy subjects (aged 18-55). Afterwards, the results were ranked from low to high irritant potential and an irritation score was calculated. Furthermore, the cleaning performance was tested using an automated cleansing device in 10 healthy subjects (aged 18-55).

RESULTS

The results confirmed the low irritant potential of laureth-23 and blends thereof. Within the different laureth-23 surfactant combinations, the combination of laureth-23 with a mild amphoteric and a mild anionic surfactant was superior to other laureth-23 surfactant combinations like laureth-23/anionic/anionic regarding skin compatibility as well as cleaning performance.

CONCLUSION

In conclusion, laureth-23 showed very good performance as a primary surfactant. Especially, the combination of laureth-23, cocamidopropyl betaine and disodium laureth sulfosuccinate was mild to the skin while also showing good cleansing performance.

Formulation characterization of lecithin organogel as topical drug delivery system for psoriasis: In-vitro permeation and preclinical evaluation

Psoriasis is a chronic inflammatory and proliferative skin disease that causes pathological skin changes and has a substantial impact on the quality of patient life. Apremilast was approved by the US Food and Drug Administration as an oral medication for psoriasis and is beneficial in mild to moderate conditions for chronic usage. However, 5%-7% of withdrawals were reported due to severe side effects. To address the issue, a localized drug delivery strategy via the topical route may be a viable approach. However, poor physicochemical properties make it vulnerable to passing through the skin, requiring a specialized drug delivery system to demonstrate its full potential via a topical route like lecithin organogel. The formulation was optimized by screening the suitable lecithin type and non-polar solvents based on the gel formation ability of lecithin and the solubility of apremilast in the solvent. The pseudo-ternary diagram was used to optimize the water content required to form the gel. The optimized gel was found to be shear thinning characterized for rheological parameters, in-vitro diffusion studies, and in-vitro skin distribution studies. Preclinical studies in Imiquimod-induced mice showed a better reduction in severity index, cytokine levels, and epidermal hyperplasia from the lecithin organogel group compared to the apremilast oral administration and marketed standard topical gel group. Based on these results, lecithin organogel can be considered a promising approach to deliver molecules like apremilast by topical route in psoriatic-like conditions.

Dynamic covalent surfactants and their uses in the development of smart materials

Dynamic covalent chemistry, which leverages the dynamic nature of reversible covalent bonds controlled by the conditions of reaction equilibrium, has demonstrated great potential in diverse applications related to both the stability of covalent bonds and the possibility of exchanging building blocks, imparting to the systems the possibility of "error checking" and "proof-reading". By incorporating dynamic covalent bonds into surfactant molecular architectures, combinatorial libraries of surfactants with bespoke functionalities can be readily fabricated through a facile strategy, with minimum effort in organic synthesis. Consequently, a multidisciplinary field of research involving the creation and application of dynamic covalent surfactants has recently emerged, which has aroused great attention in surfactant and colloid science, supramolecular chemistry, self-assembly, smart materials, drug delivery, and nanotechnology. This review reports results in this field published over recent years, discusses the possibilities presented by dynamic covalent surfactants and their applications in developing smart self-assembled materials, and outlines some future perspectives.

Skin care types, frequencies and products: A cross-sectional study in German institutional long-term care

AIM

The aim of the study was to describe types and frequencies of skin care interventions and products provided in institutional long-term care.

MATERIALS AND METHODS

Baseline data from a cluster randomized controlled trial conducted in nursing homes in Berlin, Germany was collected before randomization. Numbers, proportions and frequencies of washing, showering and bathing, and the application of leave-on products were calculated. Product labels were iteratively and inductively categorized into overarching terms and concepts.

RESULTS

A total of n = 314 residents participated in the study. In the majority, washing of the whole body was done once daily, and showering was performed once per week or more rarely. The majority received leave-on products daily on the face and once per week on the whole body. Most of the skin care interventions were delivered by nurses. There was marked heterogeneity in terms of product names, whereas the product names reveal little about the ingredients or composition.

CONCLUSION

Personal hygiene and cleansing interventions are major parts of clinical practice in long-term care. Daily washing is a standard practice at the moment. In contrast, leave-on products are used infrequently. To what extent the provided care promotes skin integrity is unclear. Due to the heterogeneity and partly misleading labels of skin care products, informed decision making is difficult to implement at present.

CLINICALTRIALS

GOV IDENTIFIER

NCT03824886.

Computational predictions of interfacial tension, surface tension, and surfactant adsorption isotherms

All-atom (AA) molecular dynamics (MD) simulations are employed to predict interfacial tensions (IFT) and surface tensions (ST) of both ionic and non-ionic surfactants. The general AMBER force field (GAFF) and variants are examined in terms of their performance in predicting accurate IFT/ST, γ, values for chosen water models, together with the hydration free energy, ΔGhyd, and density, ρ, predictions for organic bulk phases. A strong correlation is observed between the quality of ρ and γ predictions. Based on the results, the GAFF-LIPID force field, which provides improved ρ predictions is selected for simulating surfactant tail groups. Good γ predictions are obtained with GAFF/GAFF-LIPID parameters and the TIP3P water model for IFT simulations at a water-triolein interface, and for GAFF/GAFF-LIPID parameters together with the OPC4 water model for ST simulations at a water-vacuum interface. Using a combined molecular dynamics-molecular thermodynamics theory (MD-MTT) framework, a mole fraction of C12E6 molecule of 1.477 × 10-6 (from the experimental critical micelle concentration, CMC) gives a simulated surface excess concentration, ΓMAX, of 76 C12E6 molecules at a 36 nm2 water-vacuum surface (3.5 × 10-10 mol cm-2), which corresponds to a simulated ST of 35 mN m-1. The results compare favourably with an experimental ΓMAX of C12E6 of 3.7 × 10-10 mol cm-2 (80 surfactants for a 36 nm2 surface) and experimental ST of C12E6 of 32 mN m-1 at the CMC.

Toward the eco-friendly cosmetic cleansing assisted by the micro-bubbly jet

While numerous types of chemical cosmetic cleansers have been presented, those with sensitive skin may still experience some irritation while using them. Moreover, the environmental issue of chemical agents has been documented repeatedly. To address these, we suggest the potential application of a micro-sized bubble-laden water jet to cleanse the cosmetics without (or less) using chemical detergents. We devised a venturi-type nozzle with a mesh and air holes capable of generating massive fine bubbles. By testing with the foundation and lip tint (known to be highly adhesive) coated on the synthetic leather and artificial skin surfaces, we measured that the cleansing performance of the bubbly jet is much better (even without the chemical agent) than the single-phase liquid jet. As a mechanism for enhanced removal, it is understood that the greater kinetic energy of the jet due to the acceleration of the effective liquid-air mixture flow and the direct bubble-cosmetic collisions play essential roles. We believe that the present results will spur the development of environment-friendly cleaning methods.

Towards the Development of a Smart Detergent with Enhanced Safety and Efficiency for Pesticide Residue Removal from Fruits and Vegetables

The research focused on the development and evaluation of special detergents for washing fruits and vegetables, with the primary emphasis on removing pesticide residues. The research aimed to improve food safety and meet consumer preferences for effective cleaning of food products. Using the cloud point characteristic of non-ionic surfactants, a 'smart' detergent was developed to adapt to typical washing conditions. Optimization of the detergent system composition was conducted and the properties of the surfactant system in relation to the cloud point were investigated to highlight the importance of precise control over detergent behavior in response to temperature changes. The physicochemical properties study of the model washing baths included surface tension, aggregate size, solubilization properties, and foaming ability. A model detergent, tailored for both cleaning efficacy and safety against the skin, was developed. Washing efficacy tests demonstrated the superior ability of the designed detergent to remove pesticide residues, eliminating consumer concerns and promoting healthier and safer food consumption. The conducted research paves the way for innovative and safe detergents for washing fruits and vegetables, thereby increasing food safety and consumer satisfaction.

New Insights into Pharmaceutical Nanocrystals for the Improved Topical Delivery of Therapeutics in Various Skin Disorders

Nanotechnology has provided nanostructure-based delivery of drugs, among which nanocrystals have been investigated and explored for feasible topical drug delivery. Nanocrystals are nano-sized colloidal carriers, considered pure solid particles with a maximum drug load and a very small amount of stabilizer. The size or mean diameter of the nanocrystals is less than 1 μm and has a crystalline character. Prominent synthesis methods include the utilization of microfluidic- driven platforms as well as the milling approach, which is both adaptable and adjustable. Nanocrystals have shown a high capacity for loading drugs, utilization of negligible amounts of excipients, greater chemical stability, lower toxic effects, and ease of scale-up, as well as manufacturing. They have gained interest as drug delivery platforms, and the significantly large surface area of the skin makes it a potential approach for topical therapeutic formulations for different skin disorders including fungal and bacterial infections, psoriasis, wound healing, and skin cancers, etc. This article explores the preparation techniques, applications, and recent patents of nanocrystals for treating various skin conditions.

Surfactants in water and wastewater (greywater): Environmental toxicity and treatment options

Surfactant, an emerging pollutant present in greywater, raises the toxicity levels in the water body. Soap, detergent, and personal care items add surfactant to greywater. Due to excessive washing and cleaning procedures brought on by the COVID-19 pandemic, the release of surfactants in greywater has also increased. Considering the environmental toxicity and problems it creates during the treatment, it's essential to remove surfactants from the wastewater. This review intends to explain and address the environmental toxicity of the surfactant released via greywater and current techniques for surfactant removal from wastewater. Various physical, chemical, and biological methods are reported. Modern adsorbents such as hydrophilic silica nanoparticles, chitosan, fly ash, and iron oxide remove surfactants by adsorption. Membrane filtration effectively removes surfactants but is not cost-effective. Coagulants (chemical and natural coagulants) neutralize surfactant charges and help remove them as bigger particles. Electrocoagulation/electroflotation causes surfactants to coagulate and float. Microorganisms break down surfactants in microbial fuel cells to generate power. Surfactants are removed by natural processes and plants in constructed wetlands where traditional aerobic and anaerobic approaches use microbes to break down surfactants. Constructed wetlands, natural coagulation-flocculation, and microbial fuel cells are environmentally beneficial methods to remove surfactants from wastewater.

Phase Diagram of Pickering Emulsions Stabilized by Cellulose Nanocrystals

Cellulose is a promising renewable and biocompatible biopolymer for stabilizing Pickering emulsions (PEs). In the present study, PEs were produced by low-frequency ultrasounds with cellulose nanocrystals (CNCs) and caprylic/capric triglycerides. Phase diagrams allowed to understand mechanisms of formation and long-term stabilization of PEs. Emulsion type, continuous phase viscosity, and yield of oil incorporation were studied after PEs formation. Droplet size, oil release, and stability were measured weekly up to 56 days of storage. Results showed that oil mass fraction above 70% w/w led to unstable W/O PEs. Lower oil mass fraction formed O/W PEs of stability depending on CNC content and oil mass fraction. Droplet size stability increased with CNCs/oil ratio. A very low CNCs/oil ratio led to phase separation and oil release. High CNC content stabilized oil droplets surface, increased aqueous phase viscosity, and prevented creaming. Highly stable PEs were produced for CNC content above 3% (w/w) and oil mass fraction below 50% (w/w). Mechanisms for PEs formation and stabilization were proposed for various CNC contents and oil mass fractions.

Meloxicam emulgel potently suppressed cartilage degradation in knee osteoarthritis: Optimization, formulation, industrial scalability and pharmacodynamic analysis

BACKGROUND AND OBJECTIVE

Meloxicam (MLX) is prescribed for the management of pain and inflammation allied with osteoarthritis (OA). However, MLX causes intestinal damage in long term administration. Hence, meloxicam loaded emulgel (MLX-emulgel) was optimized, formulated and examined under stringent parameters in monosodium-iodoacetate (MIA) induced knee OA in Wistar rats.

METHODS AND RESULTS

Nanoemulsion of MLX was fabricated by ultrasonication and microfluidization method with a droplet size of 66.81 ± 5.31-nm and zeta potential of -24.6 ± 0.72-mV. Further, MLX nanoemulsion was optimized with centrifugation, heating-cooling cycles and transmittance parameters in addition to scale-up feasibility with microfluidizer. Post optimization, MLX-nanoemulsion was tailored as emulgel with Carbopol Ultrez 10 NF and assessed for pH, rheology, textural properties, assay and stability features. The in-vitro release study revealed the Korsmeyer-Peppas release kinetics and ex-vivo skin permeation was improved by 6.71-folds. The skin distribution of MLX-emulgel evinced the transfollicular mode of permeation. In-vivo study indicated the protective action of MLX-emulegl expressed in terms of inflammatory cyctokines level, X-ray analysis of knee joints of rats, histopathology and OARSI (Osteoarthritis Research Society International) scoring. MLX-emulgel treated group displayed lower (P < 0.001) level of COX-2 intensity as compared to positive control group. However, it was comparable (P > 0.05) to the normal control group, MLX oral dispersion, i.v. solution and etoricoxib gel groups. MLX-emulgel showcased an alternative to the long term usage of analgesics for relieving the symptoms of knee OA.

CONCLUSION

MLX-emulgel may be a potential candidate for translating in to a clinically viable dosage form in the management of knee OA.

Glycolipid Biosurfactants in Skincare Applications: Challenges and Recommendations for Future Exploitation

The 21st century has seen a substantial increase in the industrial applications of glycolipid biosurfactant technology. The market value of the glycolipid class of molecules, sophorolipids, was estimated to be USD 409.84 million in 2021, with that of rhamnolipid molecules projected to reach USD 2.7 billion by 2026. In the skincare industry, sophorolipid and rhamnolipid biosurfactants have demonstrated the potential to offer a natural, sustainable, and skin-compatible alternative to synthetically derived surfactant compounds. However, there are still many barriers to the wide-scale market adoption of glycolipid technology. These barriers include low product yield (particularly for rhamnolipids) and potential pathogenicity of some native glycolipid-producing microorganisms. Additionally, the use of impure preparations and/or poorly characterised congeners as well as low-throughput methodologies in the safety and bioactivity assessment of sophorolipids and rhamnolipids challenges their increased utilisation in both academic research and skincare applications. This review considers the current trend towards the utilisation of sophorolipid and rhamnolipid biosurfactants as substitutes to synthetically derived surfactant molecules in skincare applications, the challenges associated with their application, and relevant solutions proposed by the biotechnology industry. In addition, we recommend experimental techniques/methodologies, which, if employed, could contribute significantly to increasing the acceptance of glycolipid biosurfactants for use in skincare applications while maintaining consistency in biosurfactant research outputs.

Rhamnolipid Self-Aggregation in Aqueous Media: A Long Journey toward the Definition of Structure–Property Relationships

The need to protect human and environmental health and avoid the widespread use of substances obtained from nonrenewable sources is steering research toward the discovery and development of new molecules characterized by high biocompatibility and biodegradability. Due to their very widespread use, a class of substances for which this need is particularly urgent is that of surfactants. In this respect, an attractive and promising alternative to commonly used synthetic surfactants is represented by so-called biosurfactants, amphiphiles naturally derived from microorganisms. One of the best-known families of biosurfactants is that of rhamnolipids, which are glycolipids with a headgroup formed by one or two rhamnose units. Great scientific and technological effort has been devoted to optimization of their production processes, as well as their physicochemical characterization. However, a conclusive structure–function relationship is far from being defined. In this review, we aim to move a step forward in this direction, by presenting a comprehensive and unified discussion of physicochemical properties of rhamnolipids as a function of solution conditions and rhamnolipid structure. We also discuss still unresolved issues that deserve further investigation in the future, to allow the replacement of conventional surfactants with rhamnolipids.

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.

A win-win scenario for antibacterial activity and skin mildness of cationic surfactants based on the modulation of host-guest supramolecular conformation

The commercial cationic surfactants (CSAa) with quaternary ammonium (QA) groups have proved to be broad-spectrum bactericide against bacteria, fungi, and viruses. Nevertheless, they inevitably exhibit potent irritation on the skin. In this work, we systematically investigated the regulatory mechanism of the host-guest supramolecular conformation with β-cyclodextrin (β-CD) on the bactericidal performance and skin irritation of CSAa with different head groups and chain lengths. When the ratio of incorporated β-CD is not greater than 1:1, the bactericidal efficiency of CSAa@β-CD (n > 12) remained above 90 % due to the free QA groups and hydrophobic fraction that can act on negatively charged bacterial membranes. And once the ratio of β-CD exceeded 1:1, the β-CD attracted to the bacterial surface by hydrogen bonding might prevent CSAa@β-CD from acting on bacteria, resulting in a decrement in antibacterial performance. Even so, the antibacterial activity of CSAa with long alkyl chains (n = 16, 18) was independent from the complexation of β-CD. Accordingly, both the zein solubilization assay and the neutrophil migration assay on zebrafish skin evidenced that β-CD attenuated the interaction of surfactant with skin model proteins and the inflammatory effect on zebrafish, thereby enhancing skin mildness. In this way, we hope to create a simple but effective brainpower using the host-guest approach to guarantee both bactericidal efficiency and skin mildness without modifying the chemical structure of these commercial biocides.

Irritative potential of different washing procedures used for heavy-duty soiling: Short and intense or longer and mild?

BACKGROUND

To prevent irritant contact eczema even in occupational fields with heavy-duty soiling, it is generally recommended to use 'mild' hand cleansers (mild detergent without grits, MC). On the other hand, since grit-containing cleansers (GC) show a higher washing power that minimizes washing time, their usage is generally preferred in specific occupational fields.

OBJECTIVES

To compare whether a shorter, intense washing period might cause less skin damage than a longer washing period with an MC.

METHODS

Differences in cleaning time were first verified in a pilot study using standardized model dirt. In the main study, the forearms of 35 healthy volunteers were washed with three standardized procedures over a period of 3 days, either using 2 min of MC with/without hand brush or 1-min GC. Clinical scoring, transepidermal water loss (TEWL), corneometry, colourimetry and scaliness/roughness (Visioscan) were used to evaluate the epidermal barrier, topography and irritation.

RESULTS

The pre-study showed that washing time doubled when using MC vs. GC. Using GC resulted in stronger barrier disruption, even after a shorter washing period - median ΔT4-T1 TEWL 0.96 g/m² /h vs. 4.91 g/m² /h respectively, p < 0.0001. The most harmful procedure for the skin was the additional application of a hand brush (18.86 g/m² /h).

CONCLUSIONS

Short-time washing with GC damages the skin barrier more significantly in comparison to a longer application of an MC. When washing with MC, the strongest irritant reaction occurred when accompanied with hand brushing.

Characterisation of cytotoxicity and immunomodulatory effects of glycolipid biosurfactants on human keratinocytes

Skin irritation and allergic reactions associated with the use of skincare products formulated with synthetically derived surfactants such as sodium lauryl ether sulphate (SLES) have encouraged the search for naturally derived and biocompatible alternatives. Glycolipid biosurfactants such as sophorolipids (SL) and rhamnolipids (RL) offer a potential alternative to SLES. However, most studies on the bioactive properties of microbial glycolipids were determined using their mixed congeners, resulting in significant inter-study variations. This study aims to compare the effects of highly purified SL (acidic and lactonic) and RL (mono-RL and di-RL) congeners and SLES on a spontaneously transformed human keratinocyte cell line (HaCaT cells) to assess glycolipids' safety for potential skincare applications. Preparations of acidic SL congeners were 100% pure, lactonic SL were 100% pure, mono-RL were 96% pure, and di-RL were 97% pure. Cell viability using XTT assays, cell morphological analyses, and immunoassays revealed that microbial glycolipids have differing effects on HaCaT cells dependent on chemical structure. Compared with SLES, acidic SL and mono-RL have negligible effects on cell viability, cell morphology, and production of pro-inflammatory cytokines. Furthermore, at non-inhibitory concentrations, di-RL significantly attenuated IL-8 production and CXCL8 expression while increasing IL-1RA production and IL1RN expression in lipopolysaccharide-stimulated HaCaT cells. Although further studies would be required, these results demonstrate that as potential innocuous and bioactive compounds, microbial glycolipids could provide a substitute to synthetic surfactants in skincare formulations and perform immunopharmacological roles in topical skin infections such as psoriasis. KEY POINTS: • Purified glycolipid congeners have differing effects on human keratinocytes. • Compared with SLES, acidic sophorolipids and mono-rhamnolipids have innocuous effects on keratinocytes. • Di-rhamnolipids and mono-rhamnolipids modulate cytokine production in lipopolysaccharide stimulated human keratinocytes.

Study and optimization of oil-in-water emulsions formulated by low- and high-frequency ultrasounds

OBJECTIVE

A combined treatment using both low-frequency (20 kHz) and high-frequency ultrasounds (1.63 MHz) is a promising new process to stabilize emulsions with minimalist formulation. In order to optimize process parameters, a Doehlert experimental design was performed with oil-in-water emulsions, presently used for cosmetic products, composed of water, caprylic/capric triglycerides and oleic acid.

METHODS

Effects of treatment time, oil content and oleic acid content were studied on emulsion properties (droplet size, polydispersity index, ζ-potential and yield of oil incorporation) and on emulsion stability after a 28-day storage (creaming index, Turbiscan stability index (TSI) and oil release).

RESULTS

From experimental data, a model was established that allowed to study effects of each parameter and their interactions on emulsion formation and stability. Oleic acid content had a great impact on emulsion formation: It reduced droplet size, PDI and ζ-potential and increased yield of oil incorporation. However, a critical value could be highlighted, beyond which oleic acid effects reversed. Treatment time had an important beneficial effect on emulsion stability as it decreased creaming index, TSI and oil release after 28 days of storage. Oil content had a negative effect on emulsion formation and on emulsion stability. However, treatment time and oil content often had a beneficial synergistic effect.

CONCLUSION

The optimized conditions for emulsion processing were obtained through a desirability approach. They were experimentally validated.

Full factorial design, physicochemical characterization, ex vivo investigation, and biological assessment of glutathione-loaded solid lipid nanoparticles for topical application

l-Glutathione (GSH) has exceptional antioxidant activities against UVA irradiation-induced oxidative stress and is used widely for combatting skin ageing. However, topical administration of GSH is challenging due to its inability to penetrate the stratum corneum (SC). This study aims to evaluate the solid lipid nanoparticles (SLNs) carrier system for improving the skin penetration and stability of GSH. The GSH-loaded SLNs (GSH-SLNs) were prepared by the double emulsion technique and were optimized by a full factorial design. The optimized GSH-SLNs formulation had a mean particle size of 305 ± 0.6 nm and a zeta potential of + 20.1 ± 9.5 mV, suitable for topical delivery. The ex-vivo penetration study using human skin demonstrated a 3.7-fold improvement of GSH penetration across SC with GSH-SLNs when compared with aqueous GSH. GSH-SLNs prolonged antioxidant activity on UVA irradiated fibroblast cells when compared to GSH solution, preventing UVA-induced cell death and promoting cell growth for times over 48 h. This research has illustrated that as a carrier system, SLNs were able to enhance the physicochemical stability, skin penetration, and drug deposition in the viable epidermis and dermis layers of the skin for GSH, while also maintaining the ability to protect human skin fibroblast cells against oxidative stress caused by UVA irradiation. This delivery system shows future promise as a topical delivery platform for the topical delivery of GSH and other chemically similar bioactive compounds for improving skin health.

Interaction of surfactants with phospholipid vesicles in the low concentration regime

The interactions between diluted phospholipid vesicles (0.3 μM - 40 μM) and surfactants (around their cmc) have been investigated as model of the phenomena taking place when enveloped viruses are challenged by detergent formulations such as mouthwashes or dishwashing liquids. We have used negatively charged Small Unilamellar Vesicles (SUVs) to simulate the negatively charged viral envelope and surfactants with different charges: the anionic Sodium Dodecyl Sulphate (SDS), the cationic Cetylpyridinium Chloride (CPC) and the non-ionic Octaethylene glycol monodecyl ether (C₁₀E₈). Dynamic and Electrophoretic Light Scattering have been used to probe variations in size and surface charge of the vesicles. The surfactants effect on the membrane permeability was investigated by measuring the fluorescence of SUVs secluding the fluorophore calcein. All the surfactants perturb the bilayer inducing graded dye leakage. Irrespective of the chemical nature of the surfactant, the membrane leakage follows the same sigmoidal master curve when it is plotted against the ratio surfactant concentration/cmc. The membrane leakage is negligible below cmc/2 and above such a value increases up to the cmc where all the dye has been fully released. For ionic SDS and CPC the dependence of leakage halftime on such a scaled concentration is the same irrespective of the charge of the surfactant and the vesicles. The nonionic surfactant C₁₀E₈ induces the dye release from the SUV two orders-of-magnitude faster than the ionic surfactants. These results show that the rate-determining parameter for the permeabilization of the lipid bilayers is the electrostatic penalty to the flip-flop required to transport the surfactant inside the vesicle.

Evaluation of Skin Irritation of Acids Commonly Used in Cleaners in 3D-Reconstructed Human Epidermis Model, KeraSkinTM

Cleaners such as dishwashing liquids contain various chemicals that cause skin damage. Alkaline agents used in cleaners alter the lipid composition of the skin and damage the skin barrier. However, little is known about the effects of acids used in cleaners on the skin. Here, we investigated the effects of acidic pH on the skin and evaluated the skin irritation of acids commonly used in cleaners with a 3D-reconstructed human epidermis model, KeraSkin^TM, according to OECD TG439. First, to examine the effects of acidic pH, we evaluated the skin irritation of citrate buffers (0.1 M, McIlvaine buffer) prepared in a wide pH range (pH 1.5-6.0). Surprisingly, cell viability was not significantly affected even at pH 1.5, reflecting that the acidity alone may not be sufficient to induce skin irritation. Even after longer exposure (180 min), the cell viability was not reduced below 50%, a cutoff to determine an irritant. To examine the effect of the anionic part, several organic acids used in cleaners (citric acid, glycolic acid, lactic acid, malic acid, and succinic acid) were examined. These organic acids also failed to reduce viability at 0.1 M. However, at 1 M, most of the acids tested, except lactic acid, were determined to be skin irritants. Histology further supported the skin irritancy of acids at 1 M. Similarly, inorganic acids (hydrogen bromide, hydrogen chloride, nitric acid, and sulfuric acid) were determined to be irritants only at 1 M. In the case of alkaline agents, pH and concentrations were also important factors to determine the skin irritancy, although the epidermal structure and lipids were more damaged than acids. Collectively, we demonstrated that both the pH and concentration are important factors for the skin irritancy of acids, shedding an important insight into the mechanism of skin irritation.

Effect of New Surfactants on Biological Properties of Liquid Soaps

Liquid soaps are the basic cosmetics used to clean the skin of the hands. Frequent hand washing prevents viral contamination but may damage the skin’s hydro-lipid layer, leading to various types of irritation. Therefore, four liquid soap formulas were developed with three amphoteric surfactants: Cocamidopropyl Betaine (LS II), CocamidopropylHydroxysultaine (LS III), and newly synthesized Evening PrimroseaamidopropylSulfobetaine (LS IV). We evaluated the skin irritating potential (zein number, bovine albumin test) and cytotoxicity (AlamarBlue™, Cell viability, and Cell cycle assays) on HaCaT cell line. We observed lower values of the zein number and bovine albumin tests after adding soaps with surfactants (the highest differences in LS IV) compared to the base soap (LS I). However, LS I and LS II did not differ in cytotoxic assays. Therefore, adding LS III and LS IV seems potentially more dangerous to the cells. However, it should be noted that cells were continuously exposed to liquid soaps for more than 24 h, so its cytotoxic effects after dermal use in humans may be unnoticeable. Concluding, results suggest that the newly synthesized LS IV should improve the safety of liquid hand washing soaps.

Assessment of Cosmetic Properties and Safety of Use of Model Washing Gels with Reishi, Maitake and Lion's Mane Extracts

Natural cosmetics are becoming more and more popular every day. For this reason, this work investigates the properties of mushroom extracts, which are not as widely used in the cosmetics industry as plant ingredients. Water extracts of Grifolafrondosa (Maitake), Hericiumerinaceus (Lion's Mane) and Ganoderma lucidum (Reishi) were tested for their antioxidant properties, bioactive substances content, skin cell toxicity, ability to limit TEWL, effect on skin hydration and pH, and skin irritation. Our research showed that Maitake extract contained the highest amount of flavonoids and phenols, and also showed the most effective scavenging of DPPH and ABTS radicals as well as Chelation of Fe2+ and FRAP radicals, which were 39.84% and 82.12% in a concentration of 1000 µg/mL, respectively. All tested extracts did not increase the amount of ROS in fibroblasts and keratinocytes. The addition of mushroom extracts to washing gels reduced the irritating effect on skin, and reduced the intracellular production of free radicals, compared with the cosmetic base. Moreover, it was shown that the analyzedcosmetics had a positive effect on the pH and hydration of the skin, and reduced TEWL.

Sophorolipid Suppresses LPS-Induced Inflammation in RAW264.7 Cells through the NF-κB Signaling Pathway

Objectives: Biosurfactants with anti-inflammatory activity may alleviate skin irritation caused by synthetic surfactants in cleaning products. Sophorolipid (SL) is a promising alternative to synthetic surfactants. However, there are few reports on the anti-inflammatory activity of SL and the underlying mechanism. The purpose of this work is to verify that lipopolysaccharide (LPS)-induced inflammation could be inhibited through targeting the pathway of nuclear factor-κB (NF-κB) in RAW264.7 cells. Methods: The influence of SL on cytokine release was investigated by LPS-induced RAW264.7 cells using ELISA. The quantification of the protein expression of corresponding molecular markers was realized by Western blot analysis. Flow cytometry was employed to determine the levels of Ca²⁺ and reactive oxygen species (ROS). The relative expression of inducible nitric oxide synthase (INOS) and cyclooxygenase-2 (COX-2) was determined by RT-PCR. An immunofluorescence assay and confocal microscope were used to observe the NF-κB/p65 translocation from the cytoplasm into the nucleus. The likely targets of SL were predicted by molecular docking analysis. Results: SL showed anti-inflammatory activity and reduced the release of inflammatory cytokines including interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and nitric oxide (NO). The experimental results show that SL suppressed the Ca²⁺ and ROS levels influx in the LPS-induced RAW264.7 cells and alleviated the LPS-induced expression of iNOS and COX-2, the LPS-induced translocation of NF-κB (p65) from the cytoplasm into the nucleus, and the expression of phosphorylated proteins such as p65 and IκBα. Furthermore, molecular docking analysis showed that SL may inhibit inflammatory signaling by competing with LPS to bind TLR4/MD-2 through hydrophobic interactions and by inhibiting IKKβ activation through the hydrogen bonding and hydrophobic interactions. Conclusion: This study demonstrated that SL exerted anti-inflammatory activity via the pathway of NF-κB in RAW264.7 cells.

Effect of Talc Particle Size in Detergents for Fruits and Vegetables on the Ability to Remove Pesticide Residues

Detergents containing abrasive talc particles for washing fruits and vegetables were designed and investigated. Detergent prototypes were developed with the following composition: 40% talc particles, 1.5% surfactants, 5% ethyl alcohol, 1% sodium citrate, 1% sodium carbonate, 1.5% glycerin, and 0.5% preservative. Xanthan gum (0.5% concentration) was used as a viscosity modifier to stabilize the dispersion of talc particles. Three types of detergent prototypes were prepared, differing in the size of the talc particles. The following fractions were used: 50-125, 250-500, and 710-1000 μm. The particle size effect on the effectiveness of the removal of surface pesticide residues was investigated. A specially developed methodology was used. Three types of pesticides (boscalid, acetamiprid, and pyraclostrobin) were applied to a cherry tomato, tangerine, and cucumber, and then a model washing process was performed using the developed detergents. The changes in the pesticide content on the surface of fruit and vegetables were assessed by liquid chromatography-tandem mass spectrometry. Detergents with talc particles of sizes 50-125 and 250-500 μm were more efficient in the removal of pesticide residues from the surface of fruit and vegetables compared to detergents with 710-1000 μm talc particles.

Review of High-Frequency Ultrasounds Emulsification Methods and Oil/Water Interfacial Organization in Absence of any Kind of Stabilizer

Emulsions are multiphasic systems composed of at least two immiscible phases. Emulsion formulation can be made by numerous processes such as low-frequency ultrasounds, high-pressure homogenization, microfluidization, as well as membrane emulsification. These processes often need emulsifiers' presence to help formulate emulsions and to stabilize them over time. However, certain emulsifiers, especially chemical stabilizers, are less and less desired in products because of their negative environment and health impacts. Thus, to avoid them, promising processes using high-frequency ultrasounds were developed to formulate and stabilize emulsifier-free emulsions. High-frequency ultrasounds are ultrasounds having frequency greater than 100 kHz. Until now, emulsifier-free emulsions' stability is not fully understood. Some authors suppose that stability is obtained through hydroxide ions' organization at the hydrophobic/water interfaces, which have been mainly demonstrated by macroscopic studies. Whereas other authors, using microscopic studies, or simulation studies, suppose that the hydrophobic/water interfaces would be rather stabilized thanks to hydronium ions. These theories are discussed in this review.

A Sebum-Mimetic Lipid Monolayer and Its Interaction with (Bio)Surfactants

Surfactants present in cleansing formulations interact not only with the unwanted lipids accumulating on the human skin (dirt) but also with its protective lipidic layer (sebum). Development of simple models of human sebum would help to compare different surfactants and biosurfactants under the same conditions. In this contribution we propose a first monolayer model of synthetic sebum composed of lard, stearic acid, lanolin, squalane and cholesterol. The monolayer compression isotherm features a gas-liquid (G-LE1), two liquid-liquid transitions (LE1-LE2 and LE2-LC), and a collapse at πcoll = 45 mN/m. The monolayer spread on pure water and pre-compressed to π0 = 30 mN/m was exposed to four synthetic surfactants (sodium lauryl sulfate (SLS), sodium laureth sulfate (SLES), ammonium lauryl sulfate (ALS) and cocamidopropyl betaine (CAPB)) and four plant extracts (oat (Avena sativa L.), horse chestnut (Aesculus hippocastanum L.), cowherb (Vaccaria hispanica [P. Mill.] Rauschert), soybean (Glycine max L.) and soapwort (Saponaria officinalis L.)) introduced to the subphase at a dry mass content of 1% (w/w). Three modes of the monolayer-(bio)surfactant interactions were observed: (1) complete solubilization (SLS, SLES, ALS, CAPB); (2) penetration accompanied by an increase of surface pressure and elasticity but without solubilization (horse chestnut, cowherb, soapwort); (3) no interaction (oat, soybean).

Microemulsions formed by PPG-5-CETETH-20 at low concentrations for transdermal delivery of nifedipine: Structural and in vitro study

Nifedipine is a potent anti-hypertensive, which is poorly orally bioavailable on account of first-pass metabolism, short half-life, and low water solubility. This study aimed to develop a microemulsified system with low surfactant concentration and to evaluate the influence of microemulsion (ME) phase behavior on skin permeation of nifedipine, as drug model. Thereafter, MEs were obtained using PPG-5-CETETH-20, oleic acid, and phosphate buffer at pH 5.0. The selected MEs were isotropic, with droplet diameters less than 10 nm, polydispersity index < 0.25, and pH between 5.0 and 5.2. MEs presented low viscosity and Newtonian behavior. SAXS results confirmed bicontinuous and oil-in-water (o/w) MEs formation. The presence of the drug promoted only very slight modifications in the ME structure. The MEs presented ability to deliver nifedipine via the transdermal route when in comparison with the control. Nevertheless, the skin permeated and retained amounts from the o/w and bicontinuous formulations did not differ significantly. The ATR-FTIR demonstrated that both formulations promoted fluidization and disorganization of lipids and increased the drug diffusion and partition coefficients in the skin. In conclusion, PPG-5-CETETH-20 MEs obtained proved to be effective skin permeation enhancers, acting by rising the coefficients of partition and diffusion of the nifedipine in the skin.

Application of Levan-Rich Digestate Extract in the Production of Safe-to-Use and Functional Natural Body Wash Cosmetics

The study focused on the evaluation of the possibility of using a levan-rich digestate extract in the production of safe and functional body wash cosmetics. Model shower gels were designed and formulated on the basis of raw materials of natural origin. Prepared prototypes contained various extract concentrations (16.7; 33; 50%). A gel without extract was used as a reference. The samples were evaluated for their safety in use and functionality. The results showed that the use of high-concentration levan-rich digestate extract in a shower gel resulted in a significant reduction in the negative impact on the skin. For example, the zein value decreased by over 50% in relation to the preparation without the extract. An over 40% reduction in the emulsifying capacity of hydrophobic substances was also demonstrated, which reduces skin dryness after the washing process. However, the presence of the extract did not significantly affect the parameters related to functionality. Overall, it was indicated that levan-rich digestate extract can be successfully used as a valuable ingredient in natural cleansing cosmetics.

Establishment of an Epicutaneously Sensitized Murine Model of Shellfish Allergy and Evaluation of Skin Condition by Raman Microscopy

Background: Shellfish allergy is one of the most common food allergies. Recent studies have shown that sensitization to allergens via the skin is involved in the development of food allergies. In this study, a mouse model of shrimp allergy was generated by epicutaneous sensitization and used to identify skin conditions associated with susceptibility to sensitization. Methods: Four-week-old female BALB/c mice were sensitized by repeated application of 0.1 mg of tropomyosin to tape-stripped skin on days 0, 7, and 15, followed by a challenge on days 28 and 35. Results: Epicutaneously sensitized mice exhibited higher serum levels of tropomyosin-specific IgE on day 15 than control mice. After the oral challenge, model mice had higher anaphylaxis scores and lower rectal temperature. After three tape-strip treatments for sensitization, the skin was analyzed by Raman microscopy. The sensitized mice exhibited lower relative intensities of Raman bands at 399, 915, and 1073 cm−1 than control mice, which could be helpful noninvasive markers in screening for potential sensitization via the skin. Conclusions: An epicutaneous sensitization shellfish allergy model was generated. This model will be useful in studies to elucidate the pathogenesis of skin sensitization. Raman microscopy may also be valuable for capturing subtle skin changes leading to sensitization.

Confocal Raman spectroscopy at different laser wavelengths in analyzing stratum corneum and skin penetration properties of mixed PEGylated emulsifier systems

Emulsifier mixtures are widely used in cosmetics and pharmaceutics and thus, brought extensive studies for their performances on skin applications. PEG-20cetyl ether (C20) is recently proposed to induce skin irritation and is of interest to study its skin interactions when mixed with other emulsifiers. PEG-2oleyl ether (O2) and PEG-20stearyl ether (S20) are selected and in specific, 50 mM of C20, O2, S20 as well as Mix1 (50 mM C20 mixed with 50 mM O2) and Mix2 (50 mM C20 mixed with 50 mM S20) solutions were applied on skin samples. Confocal Raman spectroscopy (CRS) analyses of stratum corneum (SC) thickness and SC lipid content were performed after 4 h skin treatments. In parallel, skin penetration properties were also evaluated via CRS by applying procaine solutions with/without emulsifiers on skin samples for 24 h. In terms of the CRS measurements, two excitation wavelengths of 532 nm and 785 nm are both utilized in this study and we secondly aimed to compare their results and suitability in SC and skin analyses. Based on the experimental observations, comparable results are obtained by using both excitation wavelengths of 532 nm and 785 nm demonstrating their suitability in analyzing SC and skin samples. Thereinto, 785 nm laser wavelength shows the advantage of deeper skin penetration and allows the measurements of fluorescent skin samples; 532 nm laser wavelength enables simple measurement performance without substrate and coverslip interference. With regards to the results of emulsifier mixtures, the addition of S20 and O2 reduced the skin interactions and penetration enhancing ability of C20, giving us the hint to build milder systems with emulsifier mixtures. Besides, the CRS results of stronger skin interruption were also correlated with the higher critical micelle concentration (CMC) values of emulsifiers and their mixtures, which may provide evidence in explaining the interactions between emulsifiers and skin.