Cleansing formulations that respect skin barrier integrity

Five dimensions of cleansing: A holistic view on the facets and importance of skin cleansing

Cleansing is an important human ritual practised for hygiene, well-being and relaxation over centuries. As part of body care it is often taken for granted, yet its relevance cannot be underestimated. Although cleansing the skin may seem trivial to some, it is accepted, that this fundamental function of skin cleansing products is highly complex, diverse and crucial for a variety of reasons in the personal, public, healthcare and dermatological settings. Employing a comprehensive and strategic approach in viewing cleansing and its rituals, supports innovation, understanding and development. Apart from being a fundamental function, as far as we know, there is no comprehensive presentation of skin cleansing with all its effects besides 'removing dirt'. To our knowledge, comprehensive analyses on the multi-dimensional facets of skin cleansing are either rare or not published. Against this background, we examine the importance of cleansing in terms of function, relevance and concepts. First, the key functions and efficacies of skin cleansing were investigated by literature research. Based on this survey, the functions were analysed, sorted and merged and a novel approach to skin cleansing 'dimensions' was developed. Herewith, we took into consideration the evolution of skin cleansing in terms of concept evolution, complexity and testing methods for cleansing products and their claims. Several multi-dimensional functions of skin cleansing were identified and then established into five skin cleansing dimensions, namely: hygienic and medical importance; socio-cultural and interpersonal relevance; mood, emotion and well-being; cosmetic and aesthetic function; corneobiological interactions. It became obvious, that these five dimensions with their corresponding 11 sub-dimensions, are influenced by each other throughout history by culture and society, technical progress, scientific knowledge and consumer trends. This article presents the enormous complexity of skin cleansing. Skin cleansing has evolved from basic care up to a highly complex and diverse cosmetic product category in terms of technology, efficacy and usage routine(s). In view of future challenges, such as the effects of climate and associated lifestyle changes, the development of skin cleansing will remain an exciting and important topic and thus will finally, again, further increase the complexity of skin cleansing itself.

Sensory neuron activation from topical treatments modulates the sensorial perception of human skin

Neural signaling of skin sensory perception from topical treatments is often reported in subjective terms such as a sensation of skin "tightness" after using a cleanser or "softness" after applying a moisturizer. However, the mechanism whereby cutaneous mechanoreceptors and corresponding sensory neurons are activated giving rise to these perceptions has not been established. Here, we provide a quantitative approach that couples in vitro biomechanical testing and detailed computational neural stimulation modeling along with a comprehensive in vivo self-assessment survey to demonstrate how cutaneous biomechanical changes in response to treatments are involved in the sensorial perception of the human skin. Strong correlations are identified between reported perception up to 12 hours post treatment and changes in the computed neural stimulation from mechanoreceptors residing deep under the skin surface. The study reveals a quantitative framework for understanding the biomechanical neural activation mechanism and the subjective perception by individuals.

Evidence-Based Consensus Recommendations for Skin Care in Healthy, Full-Term Neonates in India

Purpose

Neonatal skin care practices guided by personal experience and preferences might be substantially different across different hospital settings. The aim of this consensus recommendation is to provide clinical practice guidance to healthcare practitioners on evidence-based neonatal skin care practices from delivery-to-discharge, in hospital settings.

Patients and Methods

A Scientific Advisory Board meeting on "Evidence-based Neonatal Skin Care Practices and Protocols" was held in December 2020 with an expert panel comprising neonatologists, pediatricians, obstetricians and gynecologists and pediatric dermatologist. Comprehensive literature search was performed up to 23 March 2021 using PubMed and Google Scholar to retrieve relevant evidence.

Results

Recommendations were developed on critical aspects of skin care in healthy full-term neonates including cleansing at birth, skin-to-skin care, cord care, diaper area care, initial and routine bathing, cleansers and emollients use, and criteria to choose appropriate skin care products. Recommendations include inclusion of skin assessment in routine neonatal care, first bath timing after cardio-respiratory and thermal stabilization, 6-24 hours after birth; bathing with water alone or adding a mild liquid cleanser could be considered appropriate as it does not impact the developing skin barrier; use of emollients is recommended for neonates with higher risk of development of eczema to maintain and enhance skin barrier function and integrity; and inclusion of skin care advice in neonatal discharge checklist. Importance of rigorous quality control, high-quality clinical trials for assessment of baby products, usage of products that are formulated appropriately for newborns, and full label transparency for baby products were highlighted. The panel identified gaps in literature and discussed the scope for future research.

Conclusion

These recommendations may help to standardize evidence-based skin care for healthy full-term neonates in Indian hospital settings to improve the quality of care that neonates receive in hospital and facilitate improvement in overall neonatal health outcomes.

TFOS Lifestyle: Impact of cosmetics on the ocular surface

In this report the use of eye cosmetic products and procedures and how this represents a lifestyle challenge that may exacerbate or promote the development of ocular surface and adnexal disease is discussed. Multiple aspects of eye cosmetics are addressed, including their history and market value, psychological and social impacts, possible problems associated with cosmetic ingredients, products, and procedures, and regulations for eye cosmetic use. In addition, a systematic review that critically appraises randomized controlled trial evidence concerning the ocular effects of eyelash growth products is included. The findings of this systematic review highlight the evidence gaps and indicate future directions for research to focus on ocular surface outcomes associated with eyelash growth products.

Investigation of the Chemical Content and User Comments on Facial Cleansing Products

BACKGROUND

The goal of skin cleansing is to reduce sebum and exogenous pollutants and control the skin microbiome. Surfactants in cleansers dissolve hydrophobic substances in an aqueous phase and allow them to move away from the skin's surface. The negative effect of surfactants on the skin barrier can be reduced by changing the solution properties. As a dermatologist in the group of patients we encounter in our clinical dermatology practice who recommends face wash products, we thought of conducting this research in order to determine the product contents to identify the products with the highest user satisfaction so that we can easily make the selection of the right product and direct the patients correctly.

MATERIALS AND METHODS

We planned to conduct cross-sectional research. Ten facial cleansing products sold on the most popular website that sells dermo-cosmetic products online in our country were selected. In the selection of the website, the criterion of having the most Internet traffic was sought. Internet traffic data was obtained from www.similarweb.com. The classification of the identified key ingredients according to their chemical properties was used on https://cosmeticanalysis.com. Reviews for each of the ten products in total were examined from the most recent date to the oldest.

RESULTS

We detected 87 different chemicals in ten different products. These basically consisted of surfactants, emollients (moisturizers), emulsifiers (cleansers), buffering (denaturators), herbal ingredients-antioxidants, solvents, and moisturizers. A total of 30 different surfactants were identified as the main cleaning ingredient in the examined products. Counterfeit product reporting was especially high on expensive products. No correlation was found between the number of surfactants in the products and the positive effects, such as cleansing and acne reduction and increase, and the negative effects, such as dryness, redness, burning, and smoothing/softening (p>0.05). There was a negative correlation between the cleansing effect of the products and the improvement and worsening of acne (p<0.05, p<0.001, respectively).

CONCLUSION

The bottom line is that a good facial cleansing product doesn't have to contain a lot of chemicals and surfactants. It should be kept in mind that expensive products may be counterfeit and should question whether the product is original or not on the local product detection system from the barcode number.

An improved human skin explant culture method for testing and assessing personal care products

BACKGROUND

Cultured human skin models have been widely used in the evaluation of dermato-cosmetic products as alternatives to animal testing and expensive clinical testing. The most common in vitro skin culture approach is to maintain skin biopsies in an airlifted condition at the interface of the supporting culture medium and the air phase. This type of ex vivo skin explant culture is not, however, adequate for the testing of cleansing products, such as shampoos and body washes. One major deficiency is that cleansing products would not remain confined on top of the epidermis and have a high chance of running off toward the dermal side, thus compromising the experimental procedure and data interpretation.

MATERIALS AND METHODS

Here, we describe an improved ex vivo method for culturing full-thickness human skin for the effective testing and evaluation of skin care products by topical application.

RESULTS

This newly developed ex vivo human skin culture method has the ability to maintain healthy skin tissues for up to 14 days in culture. Importantly, the model provides a quick and safe way to evaluate skin care products at different time points after single or repetitive topical applications using a combined regimen of leave-on and wash-off. We found that the results obtained using the new skin culture method are reproducible and consistent with the data collected from clinical testing.

CONCLUSION

Our new ex vivo skin explant method offers a highly efficient and cost-effective system for the evaluation and testing of a variety of personal care products and new formulations.

From decoding the perception of tightness to a clinical proof of soothing effects derived from natural ingredients in a moisturizer

OBJECTIVE

To decode the feeling of skin tightness after application of a cosmetic product and how to soothe this discomfort. To pursue this aim, we considered the ingredient's effect on stratum corneum (SC) biomechanics to differentiate between consumers prone to tightness from those that are not and correlate these effects with mechanoreceptor activation.

METHODS

In vivo clinical trials were used to assess the tightness perception dichotomy between groups of Caucasian women; in vitro experiments were used to measure the mechanical stresses induced in the SC after cleanser and moisturizer application; and in silico simulations were used to illustrate how the measured mechanical stresses in the SC result in the development of strains at the depth of cutaneous mechanoreceptors, triggering tightness perceptual responses.

RESULTS

Before any cream application, women prone to tightness tend to have a more rigid SC than their less sensitive counterparts, however cleanser application increases SC stiffness in all women. Surprisingly, no correlation was found between tightness perception and hydration measurements by the Corneometer or barrier function, as evaluated by transepidermal water loss (TEWL). Self-declared tightness and dryness scores were strongly associated with a self-described sensitive skin. After application of the optimized moisturizing formula, Osmoskin® containing natural waxes with good filming properties, consumers report a strong decrease in tightness and dryness perception. These results match with laboratory experiments where the cleanser was shown to increase SC drying stresses by 34%, while subsequent application of Osmoskin® decreased stresses by 48%. Finite element modeling (FEM), using experimental results as input, elucidates the differences in perception between the two groups of women. It makes clear that Osmoskin® changes the mechanical status of the stratum corneum, producing strains in underlying epidermis that activates multiple cutaneous mechano-receptors at a level correlated with the self-perceived comfort.

CONCLUSION

Integration of the in vivo, in vitro, and in silico approaches provides a novel framework for fully understanding how skin tightness sensations form and propagate, and how these sensations can be alleviated through the design of an optimized moisturizer.

Adverse Outcome Pathway for Antimicrobial Quaternary Ammonium Compounds

Quaternary ammonium compounds (QACs) or quats are a large class of antimicrobial chemicals used in households and institutions as sanitizers and disinfectants. These chemicals are utilized as food processing sanitizers, algicides, in the process of water treatment, and preservatives in cosmetics. The aim of this study was to determine an Adverse Outcome Pathway (AOP) whereby two widely used QACs, alkyl dimethyl benzyl ammonium chloride (ADBAC) and didecyl dimethyl ammonium chloride (DDAC), may result in respiratory tract and gastrointestinal tract effects. When inhaled or ingested, these QACs are incorporated into the epithelial cell membrane at the point of contact. With sufficient dosage, the epithelial membrane is disrupted, reducing its fluidity, and releasing cellular contents. Further, ADBAC and DDAC might disrupt mitochondrial functions leading to decreased ATP production. Both events might lead to cell death, either attributed to direct lysis, necrosis, or apoptosis. Pro-inflammatory mediators are recruited to the tissue, inducing inflammation, edema, and excess mucus production. The primary tissue-level adverse outcome is epithelial degeneration and dysplasia. Most important, no apparent metabolism or distribution is involved in QAC action. Based upon this knowledge, it is suggested to replace default Uncertainty Factors for risk assessments with a set of Data Derived Extrapolation Factors.

Evaluation of Cosmetic and Dermatological Properties of Kombucha-Fermented Berry Leaf Extracts Considered to Be By-Products

Leaves of Rubus fruticosus L., Vaccinum myrtillus L., Ribes nigrum L. and Fragaria vesca L. are considered agro-waste of the berry industry, but they can be a rich source of valuable bioactive compounds used in cosmetic industry. In this study, kombucha-fermented and non-fermented extracts were compared in terms of chemical composition and biological activity. Polyphenol compounds were identified by HPLC/DAD/ESI-MS. The antioxidant potential was analyzed by evaluating the scavenging of intracellular free radicals contained in keratinocytes and fibroblasts and by DPPH and ABTS assay, obtaining a higher radical scavenging capacity for the ferments, especially for R. fruticosus and V. myrtillus ferments. Assessment of the cytotoxicity on skin cell lines showed their positive effect on the viability of fibroblasts and keratinocytes (especially for the ferments after 10 days of fermentation). The potential anti-ageing properties were determined by their ability to inhibit the activity of metalloproteinases, obtaining almost 30% inhibition of collagenase and elastase in the case of fermented V. myrtillus. Moreover, when the samples were applied to the skin, the positive effect of ferments on skin hydration and pH was demonstrated, which indicates that kombucha berry leaf extracts may be an innovative cosmetic ingredient.

Skin Cleansing without or with Compromise: Soaps and Syndets

Products designed to cleanse the skin commonly do so through surfactant action, which leads to the lowering of the surface tension of the skin to facilitate the removal of dirt from its surface. Skin cleansers generally come in one of two types: soap-based and synthetic detergents, or syndets. While the latter can effectively maintain the native skin structure, function and integrity, the former tends to negatively affect the skin by causing barrier disruption, lipid dissolution and pH alteration. Despite this, soap is still often preferred, possibly due to the negative connotations around anything that is not perceived as 'natural'. It is, therefore, important that the science behind cleansers, especially those designed for the maintenance of healthy skin and the management of common skin conditions such as eczema, be understood by both formulators and end-users. Here, we carefully weigh the advantages and disadvantages of the different types of surfactant-the key ingredient(s) in skin cleansers-and provide insight into surfactants' physicochemical properties, biological activity and potential effects. Fine-tuning of the complex characteristics of surfactants can successfully lead to an 'optimal' skin cleanser that can simultaneously be milder in nature, highly effective and beneficial, and offer minimal skin interference and environmental impact.

Expert consensus on ceramides containing skincare in newborns and infants and potential mitigation of atopic dermatitis

INTRODUCTION

The vulnerable skin of neonates and infants is still developing anatomically and functionally and more susceptible to skin barrier disruption. The current consensus paper explores challenges in caring for neonates and infants' skin, skincare use and evaluates the role of ceramides (CERs) containing cleansers and moisturizers.

EVIDENCE AQUISITION

A panel of eight clinicians who treat neonates and infants developed a consensus paper on new-born and infant skin barrier integrity and CERs-containing skincare importance. The consensus process consisted of a modified Delphi technique. The selected information from the literature searches, coupled with the panel's opinion and experience, was used to adopt statements to provide clinical data for paediatric dermatologists, dermatologists, and paediatric healthcare providers who treat neonates and infants.

EVIDENCE SYNTHESIS

Increasingly, evidence supports skincare starting early in life, recognizing the benefits of ongoing daily use of non-alkaline cleansers and moisturizers to maintain skin barrier function. Skincare for neonates and infants should be safe, effective, and fragrance as well as sensitizing agent-free. Skincare with CERs may benefit the stratum corneum's lipid and water content.

CONCLUSIONS

When applied from birth onwards, gentle cleansers and moisturizers containing barrier lipids help maintain the protective skin barrier and soothe the skin with long-term moisturizing benefits.

The emerging role of nanotechnology in skincare

The role of cosmetic products is rapidly evolving in our society, with their use increasingly seen as an essential contribution to personal wellness. This suggests the necessity of a detailed elucidation of the use of nanoparticles (NPs) in cosmetics. The aim of the present work is to offer a critical and comprehensive review discussing the impact of exploiting nanomaterials in advanced cosmetic formulations, emphasizing the beneficial effects of their extensive use in next-generation products despite a persisting prejudice around the application of nanotechnology in cosmetics. The discussion here includes an interpretation of the data underlying generic information reported on the product labels of formulations already available in the marketplace, information that often lacks details identifying specific components of the product, especially when nanomaterials are employed. The emphasis of this review is mainly focused on skincare because it is believed to be the cosmetics market sector in which the impact of nanotechnology is being seen most significantly. To date, nanotechnology has been demonstrated to improve the performance of cosmetics in a number of different ways: 1) increasing both the entrapment efficiency and dermal penetration of the active ingredient, 2) controlling drug release, 3) enhancing physical stability, 4) improving moisturizing power, and 5) providing better UV protection. Specific attention is paid to the effect of nanoparticles contained in semisolid formulations on skin penetration issues. In light of the emerging concerns about nanoparticle toxicity, an entire section has been devoted to listing detailed examples of nanocosmetic products for which safety has been investigated.

Changes in Skin Barrier Function after Repeated Exposition to Phospholipid-Based Surfactants and Sodium Dodecyl Sulfate In Vivo and Corneocyte Surface Analysis by Atomic Force Microscopy

(1) Background: The aim of the study was to evaluate the effect of pure lecithins in comparison to a conventional surfactant on skin in vivo. (2) Methods: Physiological skin parameters were evaluated at the beginning and the end of the study (day 1 and day 4) (n = 8, healthy forearm skin) with an Aquaflux^®, skin-pH-Meter, Corneometer^® and an Epsilon^® sensor. Confocal Raman spectroscopy was employed to monitor natural moisturizing factor, urea and water content of the participants' skin. Tape strips of treated skin sites were taken and the collected corneocytes were subjected to atomic force microscopy. Circular nano objects were counted, and dermal texture indices were determined. (3) Results: Transepidermal water loss was increased, and skin hydration was decreased after treatment with SDS and LPC80. Natural moisturizing factor and urea concentrations within the outermost 10 µm of the stratum corneum were lower than after treatment with S75 or water. Dermal texture indices of skin treated with SDS were higher than skin treated with water (control). (4) Conclusions: Results suggest very good (S75) or good (LPC80) skin-tolerability of lecithin-based surfactants in comparison to SDS and encourage further investigation.

The Role of Environmental Exposures in Atopic Dermatitis

PURPOSE OF REVIEW

Although genetic factors clearly play a role in the development of atopic dermatitis (AD), the recent dramatic increase in the prevalence of AD in low- and middle-income countries is not consistent with only a role of genetic factors. These findings strongly suggest that environmental factors may play an important role in the pathogenesis of AD.

RECENT FINDINGS

We reviewed the role of gene-environment studies; in utero exposures including tobacco smoke, alcohol, maternal stress, various digestive supplements, and gestational diabetes; early-life exposures including diet, gut microbiota, antibiotics, and breastfeeding; climate including temperature, ultraviolet radiation exposure, and air pollution; and household products, indoor allergens, water hardness, pH, and skin microbiota and their effects on AD. Environmental factors definitely play a role in the pathogenesis of AD. However, identifying definitive factors continues to be difficult in the setting of conflicting evidence and the complex interactions between genotypes and the environment resulting in a multitude of AD phenotypes. All of the different environmental interactions discussed highlight the importance of intervening on multiple levels in a patient's environment to improve or even prevent AD symptoms. Further, the importance of modifying environmental factors early on in a person's life is demonstrated. When possible, all of these environmental factors should be considered in treating a patient with AD and the appropriate modifications should be made at population and individual levels.

Soft matter science and the COVID-19 pandemic

Much of the science underpinning the global response to the COVID-19 pandemic lies in the soft matter domain. Coronaviruses are composite particles with a core of nucleic acids complexed to proteins surrounded by a protein-studded lipid bilayer shell. A dominant route for transmission is via air-borne aerosols and droplets. Viral interaction with polymeric body fluids, particularly mucus, and cell membranes controls their infectivity, while their interaction with skin and artificial surfaces underpins cleaning and disinfection and the efficacy of masks and other personal protective equipment. The global response to COVID-19 has highlighted gaps in the soft matter knowledge base. We survey these gaps, especially as pertaining to the transmission of the disease, and suggest questions that can (and need to) be tackled, both in response to COVID-19 and to better prepare for future viral pandemics.

Acute skin barrier disruption alters the secretion of lamellar bodies via the multilayered expression of ABCA12

BACKGROUND

The skin barrier consists of multiple lipid-enriched layers, which are characterized by lamellar repeated structures within the intercellular space. Sodium lauryl sulfate is a well-known substance that can disrupt the skin barrier. The mechanisms underlying the barrier repair process, especially the influence of topical sodium lauryl sulfate treatment on lipid transport in the barrier recovery phase, remain unresolved.

OBJECTIVE

To understand the process of reconstruction of the intercellular lipid layer of the skin after acute barrier disruption by sodium lauryl sulfate treatment in vivo.

METHODS

Female hairless mice were treated with 3 % sodium lauryl sulfate. Transepidermal water loss measurement, histopathological analysis, and gene expression analysis were performed from 1 to 288 h after the topical application of sodium lauryl sulfate. Western blot analysis, immunofluorescence staining, and transmission electron microscopy analysis were performed to examine the expression level of ATP-binding cassette, sub-family A, member 12 (ABCA12), and the secretion level of lamellar bodies.

RESULTS

We observed rapid hyper-keratinization at the stratum corneum and the subsequent concurrent secretion of lamellar bodies into the intercellular space of the stratum corneum during the process of skin barrier recovery. ABCA12 expression associated with lipid transportation into lamellar bodies was transiently upregulated and observed in multiple layers in the upper epidermis, especially in the stratum granulosum.

CONCLUSION

The skin reacts appropriately to maintain its barrier function by first initiating hyper-keratinization and then increasing lamellar body secretion. Activation of ABCA12 is an essential factor for the recovery of skin barrier function.

Toward Milder Personal Care Cleansing Products: Fast ex vivo Screening of Irritating Effects of Surfactants on Skin Using Raman Microscopy

We report a novel Raman technique that allows fast and reliable ex vivo assessment of the irritability of personal care cleansing products to the skin in terms of the molecular-level effects such as retention of water by corneocytes, change in the packing order and content of intercellular lipids, and the structure of keratin. We test this technique for the single surfactants (dodecyl glucoside, sodium dodecyl sulfate, sodium cocoyl glycinate, lauramidopropyl betaine) that are typically used in personal care, as well as on three types of commercial soap bars (“superfat”, “syndet”, and “combar”). We find that soaking of the skin for prolonged time in pure water can cause unfolding of keratin, which is commonly considered as a signature of “harshness” when dealing with the surfactant formulations. Moreover, molecular-level signatures of irritability of the test surfactants and soaps at brief (10 min) exposure times do not follow the trend expected from their critical micelle concentrations (CMC) and collagen swelling. In particular, dodecyl glucoside has positive impact on the barrier properties of the stratum corneum (SC) and apparent detergency properties (solubilizes lipids without affecting their packing order). We also find that two qualitatively different soap bars (“superfat” and “syndet”) are similarly mild under the conditions studied, while the “combar” soap has detergency properties. These results demonstrate that to improve methodology of predicting irritability of a surfactant-based formulation, we need to study more systematically the molecular-level responses of the SC to exposure.

Thermodynamics, Microstructures, and Solubilization of Block Copolymer Micelles by Density Functional Theory

Block copolymer micelle is one of the most versatile self-assembled structures with applications in drug delivery, cosmetic products, and micellar-enhanced ultrafiltration. The key to design an effective block copolymer to form micelles is to understand how molecular architecture affects critical micelle concentrations, micellar dimensions, and partitioning of solute into the micelle. In this work, we studied micelles from nonionic block copolymers using interfacial statistical associating fluid theory a density functional theory, which explicitly includes block copolymer-water hydrogen bonding and water-water hydrogen bonding. We are able to predict and explain how micellar thermodynamic properties depend on polymer chain architecture. Dimension and aggregation of micelles are investigated for block copolymers with different hyrophobes and hydrophiles. The effects of temperature and pressure on micelle stability are also captured by the theory. The enhanced solubility of hydrophobic substance in water by micelle loading is demonstrated, and predicted solute distribution answers the question about the locus of benzene in micelles from a theoretical perspective.

Sodium Lauryl Sulfate vs. Sodium Coco Sulfate. Study of the Safety of Use Anionic Surfactants with Respect to Their Interaction with the Skin

As a result of growing awareness, consumers are increasingly interested in products that are safe on the skin and environmentally-friendly. This is one of the most important reasons for the very rapid development of the natural cosmetics segment which has been observed for several years now. Among the most commonly used anionic surfactants of natural origin are sodium lauryl sulfate (SLS) and sodium coco sulfate (SCS). As there are no unambiguous reports on the safety of using SCS, in this study an attempt was made to evaluate the effect of SCS on the skin. The results of the determination of the skin irritation potential (zein value) indicate that the analyzed parameter is approximately 15 % lower in SCS than in SLS. SCS has a stronger ability to interact with epidermal lipids and cause their elution from the skin, which in turn may damage the protective epidermal barrier. The results obtained during the evaluation of the effect produced by the analyzed substances on the metabolism of human keratinocytes (HaCaT) show that after 4 h of incubation with the studied groups of compounds there was a significant decrease in cell proliferation. The highest decrease in cell metabolism was demonstrated for SLS.

Effect of N-dodecyl-N-(propylpiperydinium-3-sulfonate) on Usage Properties of Liquid Soaps for Sensitive Skin

The aim of the study was to assess the effect of N-dodecyl-N-(propylpiperidinium-3-sulfonate) on the physico-chemical and functional properties of liquid soaps for sensitive skin. The studied materials consisted of originally formulated liquid soaps containing amphoteric surfactants including cocamidopropyl betaine and newly synthesized sulfobetaine in the following ratios: 0 : 0, 1 : 1, 0 : 2 and 2 : 0. The aim of study was to examine the effects of the additive on the surface tension of aqueous soap solutions, wetting properties, dynamic viscosity, emulsification of fatty soils, foaming properties, antimicrobial characteristics and skin irritation potential. It is shown that the liquid soaps obtained in the study effectively reduce the surface tension of water – which may indicate good washing properties – and demonstrated desirable wetting properties. The application of N-dodecyl-N-(propylpiperidinium-3-sulfonate) in cosmetic formulations makes it possible to obtain products with the required viscosity, fat emulsification capacity and foaming properties. It needs to be emphasized that sulfobetaines added to the prototypical liquid soaps also demonstrate antibacterial characteristics and reduce the skin irritant effect caused by anionic surfactants.

Action of surfactants on the mammal epidermal skin barrier

BACKGROUND

Daily skin washing routines can promote undesirable effects on skin barrier function. The stratum corneum (SC) lipid matrix is crucial for skin barrier function. Skin cleansing products are mostly composed of surfactants: surface-active molecules that interact with skin lipids in several ways. The main aim of this work was to investigate the effect produced by surfactants on skin barrier permeability. Porcine skin is a well-accepted and readily available model of the human skin barrier. The effect of two cleansing formulations (based on different surfactant mixtures) on the barrier properties of mammalian skin were evaluated.

METHODS

Water sorption/desorption (DVS) experiments were used to measure skin permeability. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and confocal Raman were useful to study SC lipid organization.

RESULTS

The results showed that while anionic surfactants (SLS) had a negative impact on the skin barrier, with a clear increase of alkyl chain disorder; cosurfactants present in the shampoo formulation diminished the detrimental effect of their primary ionic surfactant, inducing less modification on lipid intramolecular chain disorder.

CONCLUSIONS

The obtained results confirmed that the mild cleansing formulations studied had gentle interaction with skin. The capacity to discriminate between detergent systems was clearly established with both DVS and spectroscopy techniques.

Interactions between surfactants and the skin - Theory and practice

One of the primary causes of skin irritation is the use of body wash cosmetics and household chemicals, since they are in direct contact with the skin, and they are widely available and frequently used. The main ingredients of products of this type are surfactants, which may have diverse effects on the skin. The skin irritation potential of surfactants is determined by their chemical and physical properties resulting from their structure, and specific interactions with the skin. Surfactants are capable of interacting both with proteins and lipids in the stratum corneum. By penetrating through this layer, surfactants are also able to affect living cells in deeper regions of the skin. Further skin penetration may result in damage to cell membranes and structural components of keratinocytes, releasing proinflammatory mediators. By causing irreversible changes in cell structure, surfactants can often lead to their death. The paper presents a critical review of literature on the effects of surfactants on the skin. Aspects discussed in the paper include the skin irritation potential of surfactants, mechanisms underlying interactions between compounds of this type and the skin which have been proposed over the years, and verified methods of reducing the skin irritation potential of surfactant compounds. Basic research conducted in this field over many years translate into practical applications of surfactants in the cosmetic and household chemical industries. This aspect is also emphasized in the present study.

Confocal Raman microspectroscopy as an alternative to differential scanning calorimetry to detect the impact of emulsifiers and formulations on stratum corneum lipid conformation

The purpose of this study was to investigate the impact of emulsifiers and formulations on stratum corneum (SC) lipid conformation and evaluate confocal Raman microspectroscopy (CRM) as an alternative method to differential scanning calorimetry (DSC) in this research context. To this end, four different formulations were used: three conventional creams that contained ionic and/or non-ionic emulsifiers and one surfactants-free emulsion stabilized by a polymeric emulsifier. Additionally, all emulsifiers were tested in aqueous solutions/dispersions in the respective concentrations as present in the formulations. In this study, emulsifiers and formulations were applied onto excised porcine skin during incubation in Franz diffusion cells. Subsequently, SC was isolated, dried and subjected to CRM and DSC measurement to analyse lipid structural changes after treatment. In CRM measurement, 1080 cm^-1/(1130 cm^-1 + 1070 cm^-1) peak ratio, which represents the C-C skeleton vibration and trans-gauche conformation order of lipids, was investigated. Various emulsifiers and formulations showed different impact on SC lipid conformation. Specifically, cetearyl alcohol and sodium cetearyl sulfate mixture dispersion showed the strongest ability among all studied emulsifiers, followed by glycerol monostearate, polyoxyethylene-20-glycerol monostearate as well as their mixture. Polysorbate 60, cetyl stearyl alcohol and their mixture did not affect SC lipid structure. The results of CRM and DSC correlated very well, indicating CRM, as an alternative to DSC, can be a reliable method to investigate SC lipid conformation.

Improvement in the Safety of Use of Hand Dishwashing Liquids Through the Addition of Hydrophobic Plant Extracts

We investigated the effect of hydrophobic extract concentration on the safety of using hand dishwashing liquids (HDL). A series of formulations was prepared, differing in the concentration of the hydrophobic chamomile extract obtained in supercritical CO₂ conditions (from 0 to 0.7 %). We found that an increase in the concentration of the extract led to a decrease in the zein number, and reduced changes in the pH level of bovine serum albumin solution (i.e., two parameters determining the irritant activity of the formulations). It was also found that the additives reduced transepidermal water loss and improved the skin hydration level. Based on the findings of the study, a mechanism has been proposed, according to which hydrophobic plant extracts form aggregates in the volume phase of the washing bath. The surface of the aggregates is the adsorption area for surfactant monomers responsible for the irritant effect. Increasing the addition of the extract was shown to reduce the negative impact of the formulations on the skin of the hands, thus contributing to a greater safety of use of HDL.

Hydrophobically modified polymers can minimize skin irritation potential caused by surfactant-based cleansers

Introduction

The addition of hydrophobically modified polymers (HMPs) to cleansers that contain surfactants can create polymer–surfactant complexes that are less irritating to the skin than commercially available mild cleansers. Our objective was to compare the tolerability and efficacy of a test foaming liquid facial cleanser containing HMPs with a commercial liquid nonfoaming facial cleanser in women with sensitive skin.

Methods

In this randomized, prospective, double-blind, comparative study, women (n = 20 per group) with mild-to-moderate atopic dermatitis (AD), eczema, acne, or rosacea used a test gentle foaming liquid facial cleanser containing HMPs or a commercial gentle liquid nonfoaming facial cleanser daily for 3 weeks. Investigators assessed irritation and skin condition. Study subjects also assessed their skin properties and the performance of each cleanser.

Results

Clinicians as well as study subjects consistently rated the test cleanser as effective or slightly more effective at improving symptoms than the commercial cleanser, although no significant differences between groups were observed. At weeks 1 and 3, respectively, more users of the commercial cleanser reported irritation (20% and 10%) than users of the test cleanser (5% and 5%). In addition, subject self-assessments of skin condition and cleansing properties were slightly more improved with the test cleanser than with the commercial cleanser.

Conclusions

Both the test foaming cleanser containing HMPs and the commercial nonfoaming cleanser were effective and well accepted by most women in the study. Improvements were observed by both clinicians and subjects in the group using the test cleanser containing HMPs in all evaluated skin categories.