ArticleLiterature Review

Cleansing without compromise: the impact of cleansers on the skin barrier and the technology of mild cleansing

Authors:
  • The University of Edinburgh and OMERO LTD
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Cleanser technology has come a long way from merely cleansing to providing mildness and moisturizing benefits as well. It is known that harsh surfactants in cleansers can cause damage to skin proteins and lipids, leading to after-wash tightness, dryness, barrier damage, irritation, and even itch. In order for cleansers to provide skin-care benefits, they first must minimize surfactant damage to skin proteins and lipids. Secondly, they must deposit and deliver beneficial agents such as occlusives, skin lipids, and humectants under wash conditions to improve skin hydration, as well as mechanical and visual properties. While all surfactants tend to interact to some degree with lipids, their interaction with proteins can vary significantly, depending upon the nature of their functional head group. In vitro, ex vivo, and in vivo studies have shown that surfactants that cause significant skin irritation interact strongly with skin proteins. Based on this understanding, several surfactants and surfactant mixtures have been identified as "less irritating" mild surfactants because of their diminished interactions with skin proteins. Surfactants that interact minimally with both skin lipids and proteins are especially mild. Another factor that can aggravate surfactant-induced dryness and irritation is the pH of the cleanser. The present authors' recent studies demonstrate that high pH (pH 10) solutions, even in the absence of surfactants, can increase stratum corneum (SC) swelling and alter lipid rigidity, thereby suggesting that cleansers with neutral or acidic pH, close to SC-normal pH 5.5, may be potentially less damaging to the skin. Mildness enhancers and moisturizing agents such as lipids, occlusives, and humectants minimize damaging interactions between surfactants, and skin proteins and lipids, and thereby, reduce skin damage. In addition, these agents play an ameliorative role, replenishing the skin lipids lost during the wash period. The present review discusses the benefits of such agents and their respective roles in improving the overall health of the skin barrier.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... It is generally recognised [7,9,[12][13][14] that all types of skin, from healthy to diseased, infant to aged, need to be kept clean in order to preserve their barrier properties. The main objective of skin cleansing is to remove impurities from the skin's surface [15,16] and to control its odour, without removing protective SC surface proteins and lipids, affecting skin microbiota [17] or altering pH [13,18]. ...
... This makes surfactants a key component of skin maintenance. However, not all surfactants are created equal, with some, namely soap-based surfactants, creating more problems than they address [3,9,10,13,16,17,[19][20][21][22][23][24][25][26][27][28][29][30][31]. This review will: (1) compare and contrast the key attributes of soaps and syndets; (2) discuss the advantages and disadvantages of different types of surfactant and provide insight into their physicochemical properties, biological activity and potential effects; ...
... In deeper layers of the SC, lipids are predominantly ordered into a densely packed orthorhombic crystalline configuration, which acts as a restrictive barrier to liquid transport. Closer to the SC surface, the lipids form a dispersed hexagonal lattice configuration that permits more liquid to pass through more freely [9,10]. ...
Article
Full-text available
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.
... Surfactants may be classified based on the charge of the head groups: anionic (negatively charged), cationic (positively charged), non-ionic (no charge), and amphoteric (zero net charge). Non-ionic surfactants are recognized as having the mildest actions on the skin, having the lowest potential for irritation compared with other types of surfactants [102,124,125]. However, this is only confirmed for adult skin and information is lacking for infant skin. ...
... As shown in Table 7, the most commonly used surfactants in baby wipe formulations belong to the non-ionic class. In contrast, rinse-off liquid cleansers typically contain anionic surfactants because of their high foaming and lathering capacity [125]. Table 7. Common surfactants used in baby wipe formulations. ...
... With reference to baby wipes emollients are ingredients that can help to minimize SC barrier disruption by (1) avoiding frictional damage of the skin during wiping [101], (2) ameliorating the effects of interaction of surfactants and SC components (particularly lipids and proteins), and (3) replenishing the SC lipids that are lost during cleansing [125]. The use of baby wipes impregnated with emollients was reported to result in lower erythema scores and TEWL in infants (p < 0.05) compared with the use of cloth and water [106]. ...
Article
Full-text available
A good understanding of infant skin should provide a rationale for optimum management of the health of this integument. In this review, we discuss the skin barrier function of infants, particularly with reference to the use of diapers and baby wipes. The skin barrier of newborns continues to develop with age. Two years after birth, the barrier properties of infant skin closely resemble those of adult skin. However, several risk factors may contribute to impaired skin barrier and altered skin permeability in infants. Problems may arise from the use of diapers and baby wipes. The skin covered by a diaper is effectively an occluded environment, and thus is vulnerable to over-hydration. To date there has been no published information regarding dermal absorption of ingredients contained in baby wipes. Similarly, dermal absorption of topical ingredients in infants with underlying skin conditions has not been widely explored. Clearly, there are serious ethical concerns related to conducting skin permeation studies on infant skin. However, the increasing availability of non-invasive methods for in vivo studies is encouraging and offers new directions for studying this important patient group.
... Moreover, the surfactants may interact with the structure of the epidermal intercellular cement, leading to disturbances in its liquid-crystal structure, solubilization of structural lipids and their being washed out of the horny layer, or stratum corneum. This may cause delipidation of the horny layer, disturbance of its barrier functions, and higher transepidermal water loss (TEWL) values [11,42,43,[94][95][96]. ...
... The zein value measurement is a suitable research method enabling determination of the skin irritation potential of surfactants and surfactant-based finished cosmetics and household chemicals according to many reports [11][12][13][14][15]17,18,42,43,94,95]. The method is based on the structural resemblance of the zein protein and the keratin protein building the epidermis. ...
... Therefore, interactions between zein and surfactants demonstrate the impact of surfactants on the skin. The essence of the zein value measurement is determination of the amount of solubilized zein in the test solution by measuring, in the test sample, the weight of free nitrogen weight originating from the protein, by the Kiejdahl method [11,42,43,[94][95][96][97][98][99][100]. ...
Article
Full-text available
The article shows that the type and concentration of inorganic salt can be translated into the structure of the bulk phase and the performance properties of ecological all-purpose cleaners (APC). A base APC formulation was developed. Thereafter, two types of salt (sodium chloride and magnesium chloride) were added at various concentrations to obtain different structures in the bulk phase. The salt addition resulted in the formation of spherical micelles and—upon addition of more electrolyte—of aggregates having a lamellar structure. The formulations had constant viscosities (ab. 500 mPa·s), comparable to those of commercial products. Essential physical-chemical and performance properties of the four formulations varying in salt types and concentrations were evaluated. It was found that the addition of magnesium salt resulted in more favorable characteristics due to the surface activity of the formulations, which translated into adequately high wettability of the investigated hydrophobic surfaces, and their ability to emulsify fat. A decreasing relationship was observed in foaming properties: higher salt concentrations lead to worse foaming properties and foam stability of the solutions. For the magnesium chloride composition, the effect was significantly more pronounced, as compared to the sodium chloride-based formulations. As far as safety of use is concerned, the formulations in which magnesium salt was used caused a much lesser irritation compared with the other investigated formulations. The zein value was observed to decrease with increasing concentrations of the given type of salt in the composition.
... When the SC is confronted with chemicals that possess surface-active activities, it can be compromised. Many of the daily products that we apply onto our skin for cosmetic purposes, e.g., cosmetic creams or cleaning products such as soaps, washing detergents, shower gels or shampoos, contain surfactants-either as essential structural compound or as active principle in the removal of dirt [9]. ...
... In general, surfactants are key excipients in pharmaceutical and cosmetic formulation development [9][10][11]. Due to increased consumer interest and environmental aspects, there is a constant tendency towards the use of surfactants from renewable raw materials. ...
... The proper barrier function of the SC and its enzymatic activity are hugely dependent on the skin's hydration level [51]. Hydration levels influence not only skin plasticity, but also the functionality of several proteases responsible for desquamation, lipid synthesis and inflammatory responses [9,10,34]. Skin hydration as determined by corneometry was not affected after four days of treatment in case of lecithin S75 and water as control. However, significant dehydration of the SC was caused by SDS and S LPC80, where values were decreased by roughly -30% and even −40% for SDS. ...
Article
Full-text available
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 lec-ithin-based surfactants in comparison to SDS and encourage further investigation.
... For example, anionic surfactants including sodium dodecyl sulfate (SDS), sodium lauryl sulfate (SLS), and linear alkyl benzene sulfonate (LAS) cause various degrees of lipid disordering (Froebe et al. 1990;Ribaud et al. 1994;Moghadam et al. 2013;Barba et al. 2015). In addition to alterations caused by partitioning of the surfactant in SC lipid bilayers (Downing et al. 1993;Ananthapadmanabhan et al. 2004), surfactants could deplete certain SC lipids (Froebe et al. 1990;Rawlings et al. 1994;Bolzinger et al. 2012). Concentration-dependent effects were reported for SLS and LAS, with increasing amounts of lipids removed when the concentration applied exceeded its critical micelle concentration (0.24 and 0.04%, respectively). ...
... An effect of time was also reported, with lipid removal by SLS increasing for incubation times between 30 s and 10 min (Froebe et al. 1990). Some authors also suggest that, rather than damaging the skin by delipidation, SDS might alter the synthesis of new lipids (Fartasch 1997;Ananthapadmanabhan et al. 2004). ...
Article
Full-text available
Percutaneous occupational exposure to industrial toxicants can be assessed in vitro on excised human or animal skins. Numerous factors can significantly influence skin permeation of chemicals and the flux determination. Among them, the vehicle used to solubilize the solid substances is a tricky key step. A “realistic surrogate” that closely matches the exposure scenario is recommended in first intention. When direct transposition of occupational exposure conditions to in vitro experiments is impossible, it is recommended that the vehicle used does not affect the skin barrier (in particular in terms of structural integrity, composition, or enzymatic activity). Indeed, any such effect could alter the percutaneous absorption of substances in a number of ways, as we will see. Potential effects are described for five monophasic vehicles, including the three most frequently used: water, ethanol, acetone; and two that are more rarely used, but are realistic: artificial sebum and artificial sweat. Finally, we discuss a number of criteria to be verified and the associated tests that should be performed when choosing the most appropriate vehicle, keeping in mind that, in the context of occupational exposure, the scientific quality of the percutaneous absorption data provided, and how they are interpreted, may have long-range consequences. From the narrative review presented, we also identify and discuss important factors to consider in future updates of the OECD guidelines for in vitro skin absorption experiments.
... Work in humans and other species have found that skin assessments including measurement of dermal pH and trans-epidermal water loss (TEWL) correlate with skin irritation and dermal barrier function ( Korting et al., 1990( Korting et al., , 1992Korting and Braun-Falco, 1996 ;Ruedisueli et. al., 1998 ;Baranda et al., 2002 ;Rippke et al., 2002 ;Ananthapadmanabhan et al., 2004 ;Schmid-Wendtner and Korting, 2006 ;Marsella, 2012 ;Luebberding et al., 2013 ;Szczepanik et al., 2013 ;Pin et al., 2014 ;Mahrhauser et al., 2015 ;Bradley et al., 2016 ;Momota et al., 2016 ;Bradley et al., 2016 ). Harsh cleansers may compromise skin barrier, thus increasing the risk of contaminant absorption during a later deployment. ...
... Skin irritation from cleansers is commonly seen and studied in humans and canines and has been correlated with changes in dermal pH and TEWL ( Schmid and Korting, 1995 ;Korting and Braun-Falco, 1996 ;Barel et al., 2001 ;Baranda et al., 2002 ;Ananthapadmanabhan et al., 2004 ;Schmid-Wendtner and Korting, 2006 ;Marsella, 2012 ;Tarun et al., 2014 ;Zajac et al., 2014 ). Disruption of the barrier function of the skin which correlates with changes in dermal pH and TEWL, is theorized as the culprit. ...
Article
Environmental contamination is commonly experienced by working canines deployed in the field. Unfortunately, data regarding safety and efficacy of cleansers recommended for decontamination is lacking. Client-owned canines recruited from the community (n = 43) were randomly assigned to one of four treatment groups: povidone-iodine scrub [60mL Betadine® 7.5% povidone-iodine surgical scrub (Avrio Health L.P, Stamford, CT)], chlorhexidine scrub [60 mL Nolvasan® 2% chlorohexidine surgical scrub (Zoetis, Kalamazoo, MI)], dish detergent [60mL Dawn® dish detergent (Proctor & Gamble, Cincinnati, OH)], or water alone (control). A visual score assessing removal of a fluorescent marker (GloGerm, Moab, UT) applied between the shoulder blades was used to rate effectiveness of decontamination. Cleanser effect on canine dermal barrier function was determined by measuring pre- and post-decontamination dermal pH and trans-epidermal water loss (TEWL). Analysis of visual scores was performed using PROC FREQ and Chi Square. Significance was set a priori at 0.05 for all tests. Efficacy of fluorescent marker removal was significantly affected by cleanser (P<0.0001). Dermal pH was also highly affected by cleanser (P < 0.0001). In contrast, TEWL was unchanged across cleansers (P = 0.2686). Common veterinary cleansers utilized for canine decontamination demonstrate similarity in effectiveness for removal of a simulated contaminant and negative impact on dermal barrier function.
... Unfortunately, at sufficiently high concentrations they remove not only the lipids associated with the unwanted dirt, but also those constituting the protective sebum. In fact, selective dirt removal (without affecting the sebum) is practically impossible and the use of efficient detergents also removes part of the skin's natural protective barriers, exposing its deeper layers to potential toxins and allergens from the environment [5][6][7]. To minimize the damage while maintaining a maximum dirt removal efficacy, formulators often replace part of the ionic surfactants with less aggressive ones (e.g., by admixing the amphoteric cocamidopropyl betaine with the anionic SLS/SLES). ...
... The monolayers penetrated by the synthetic low-molecular weight surfactants (SLS, ALS, SLES, CAPB) undergo solubilization, as evidenced by the proximity of both π 100 and E' values for the bare surfactants (Gibbs) adsorbed layers and the surfactant-penetrated sebum monolayers. This is consistent with the known detergent activity of these ingredients, successfully employed in harsh washing/cleansing formulations [5,29,30]. Similar observations were reported for other lipid mixtures [31,32] or protein monolayers [33,34]. Despite the clear proof of the monolayer solubilization, the present data do not allow for any discussion of its detailed mechanism. ...
Article
Full-text available
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).
... Molecules 2022, 26, x FOR PEER REVIEW 11 of 23 The skin irritating effect of body wash cosmetics is mainly related to the interactions between basic surfactants, i.e., the primary ingredients of the formulation, and the stratum corneum, as well as the results of these interactions. In addition to potential adverse interactions with proteins building corneocytes in the stratum corneum and deactivation of enzymes known to play a role in healthy skin function [9,11,43], scientific studies analyzing the safety of cosmetics from the viewpoint of their skin effects also address the impact of cosmetic products in the context of hydrophobic components present in the epidermis [9,[44][45][46]. Specifically, an excessive ability to emulsify fats in body wash cosmetics carries the risk of removing valuable lipids from the epidermal protective layer, which are proven to contribute to maintaining appropriate hydration of the epidermis and strengthening the skin's barrier function. ...
... The skin irritating effect of body wash cosmetics is mainly related to the interactions between basic surfactants, i.e., the primary ingredients of the formulation, and the stratum corneum, as well as the results of these interactions. In addition to potential adverse interactions with proteins building corneocytes in the stratum corneum and deactivation of enzymes known to play a role in healthy skin function [9,11,43], scientific studies analyzing the safety of cosmetics from the viewpoint of their skin effects also address the impact of cosmetic products in the context of hydrophobic components present in the epidermis [9,[44][45][46]. Specifically, an excessive ability to emulsify fats in body wash cosmetics carries the risk of removing valuable lipids from the epidermal protective layer, which are proven to contribute to maintaining appropriate hydration of the epidermis and strengthening the skin's barrier function. ...
Article
Full-text available
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.
... These types of bar soap typically have the disadvantage of high pH, which disrupts the skin's natural mildly acidic state. More common today are synthetic detergent (syndet) bars utilizing milder surfactants like sodium cocoyl isethionate and sodium lauryl sarcosinate (13). The pH of pure soap-free syndet bars is in the range of 5 to 7, which makes them much more skin-friendly (14). ...
... Liquid cleansers were first marketed as a convenient and less messy alternative to bar soaps which left an unpleasant, gooey "soap mush" as the bars absorbed water when left in a soap dish. Much attention has been given to liquid cleanser formulation strategies to improve mildness including use of milder synthetic surfactants, blending surfactants to create more stable mixed micelles, use of polymers to limit surfactant monomer and micelle skin penetration and deposition of emollient and occlusive ingredients (13,(15)(16)(17). ...
Article
Hand hygiene plays an integral role in controlling the spread of infectious disease in healthcare and community settings. The extraordinary impact of the novel corona virus known as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) on global public health has brought a renewed emphasis on the importance of hand health and hygiene in the prevention of disease transmission and the critical role of cosmetic science in the development of effective cleansers, antiseptic hand rubs, and moisturizers that protect and repair the skin barrier
... Approximately 44% of the HCWs in this study cleaned their face with a cleanser, and a small proportion cleaned their face with soap and water. A recent study showed that cleanser surfactants in soap can cause tightness, dryness, skin barrier damage, erythema, irritation, and itching immediately after cleansing.30 Experts suggest that cleansers with a neutral or acidic pH, close to the normal pH level of 5.5 of the stratum corneum, may be potentially less damaging to the skin than using soap, which has a pH of 10.0.30 ...
... A recent study showed that cleanser surfactants in soap can cause tightness, dryness, skin barrier damage, erythema, irritation, and itching immediately after cleansing.30 Experts suggest that cleansers with a neutral or acidic pH, close to the normal pH level of 5.5 of the stratum corneum, may be potentially less damaging to the skin than using soap, which has a pH of 10.0.30 Some experts recommend avoiding the application of make-up under F-PPE.26,28 ...
Article
Full-text available
Background Healthcare workers (HCWs) report frequent adverse skin reactions (ASR) due to face personal protective equipment (F-PPE) use during the coronavirus disease 2019 pandemic. Objectives To describe self-reported ASR among HCWs using F-PPE; investigate background factors, such as chronic skin diseases and skin types (dry, oily, combination, sensitive), and determine whether HCWs took preventive methods against ASR. Methods An online questionnaire was distributed to 22 993 HCWs at hospitals. Results The prevalence of ASR was 61.9% based on 10 287 responders. Different types of F-PPE caused different reactions. The most common ASR from surgical masks were spots and pimples (37.2%) and for FFP3 masks were red and irritated skin (27.3%). A significantly higher proportion of HCWs with chronic skin diseases had ASR (71.6%) than those without (59.7%) (P < .001). Some skin types were more prone to ASR (sensitive skin [78.8%] vs. dry skin [54.3%]; P = .001). HCWs using F-PPE for >6 hours vs. <3 hours per day had four times higher ASR risk (P = <.001). Nearly all used preventive and/or counteractive methods (94.2%). Conclusions It is important to consider background factors, such as chronic skin diseases and skin types, to prevent and counteract ASR due to F-PPE use. This article is protected by copyright. All rights reserved.
... Они необходимы для более полного удаления с кожи загрязнений, в числе которых пот, кожное сало, остатки масел, топических лекарственных средств. Однако взаимодействие между очищающими поверхностно-активными веществами и белками и липидами рогового слоя может приводить к отрицательным последствиям: удалению с кожи естественного увлажняющего фактора и липидов и в конечном итоге -к развитию ксероза (сухости кожи), раздражению и зуду [20]. Важно учи тывать различия между «мылом» и моющими средствами. ...
... Мыло представляет собой соли жирных кислот, а моющие средства на основе мыла являются щелочными (pH = 10). В настоящее время доступно большое количество очищающих средств, имеющих более нейтральный или кислотный pH в сравнении с таковым у мыла, что снижает вероятность нарушения кожного барьера [20]. ...
Article
Healthy newborn skin care is challenging task. The basic principles of care should be taught to both medical staff and parents. This care is more crucial in children with atopic dermatitis who have abnormal skin acidity due to multifactorial exposure. Significant pH reduction leads to aggravation of the skin process that requires active therapeutic measures. The article presents guidelines for the first infant's skin cleaning, for conducting first and daily bathing, for using cleansing agents and daily care solutions to prevent skin acidity disorders and the development of atopic dermatitis.
... Anionic surfactants consist of negatively charged head and hydrophobic tail. Due to their favorable physicochemical characteristics in cleaning and foaming, anionic surfactants are commonly employed in diverse detergents for household, industrial, and institutional cleaning as well as personalcare cleaning (Ananthapadmanabhan et al. 2010;Morris et al. 2019). Such extensive applications have resulted in excessive release of anionic surfactants into water resources (Siyal et al. 2020). ...
... After HPTS-based surfactants entered into cell lumens, the colocalization of the red fluorescent ER-Tracker and the blue fluorescent HPTS-C16 suggested that ER should be the primary binding site of surfactants. It has been well known that ER is the major section for protein synthesis and possesses the largest membrane area among the cell organelles (Alberts et al. 2007). In this respect, the binding of surfactants with ER could readily cause cytotoxicity because anionic surfactants are supposed to alter protein structure and disrupt the phospholipid membranes (Cserháti et al. 2003). ...
Article
Full-text available
The extensive application of chemically synthesized anionic surfactants would cause serious pollution of water and increase health risk to humans. However, the adverse impact of anionic surfactant on human cells has never been systematically demonstrated. In this paper, a series of fluorescent anionic surfactants containing a varying length of alkyl chain from C8 to C18 and a fixed hydrophilic head of 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) were synthesized and utilized for visualizing the interaction between surfactants and cells. The obtained molecules exhibited blue fluorescence presenting a decreasing fluorescent intensity with the increasing length of alkyl chain from C8 to C18 while showed the same sequence of HPTS-C16>HPTS-C18>HPTS-C12>HPTS-C8 on either surface activity, cellular adsorption, or cytotoxicity. In opposite, HPTS which contained no hydrophobic chain and thus exhibited no surface activity showed no cellular adsorption and cytotoxicity. It seems that the ligand of the appropriate chain length (C16) onto the hydrophilic HPTS molecules could cause the largest surface activity, the most distinguished cellular adsorption as well as the most adverse cytotoxicity. As reflected by the dynamic fluorescent visualization, the surfactant molecules of HPTS-C16 initially bound with cell membrane and entered into the intracellular lumen before finally localized at the endoplasmic reticulum (ER) and damaged it into a swollen structure. It is most likely that the structure of hydrophobic chain could determine the surface activities of surfactants and hence affect their cellular uptake and cytotoxicity. This study could help us to understand the adverse impact of anionic surfactant on human cells and its correlation with the surface activities or, in another word, the hydrophobic chain length.
... The appropriate use of cleansing agents and moisturizing barrier cream is important for maintaining skin barrier function. 29,30 Previous studies have shown that the combined use of cleanser and moisturizers is effective for mild acne, atopic dermatitis, and diabetic skin changes. [31][32][33] Likewise, successfully eliminating PM attached to skin by using cleansing agents and applying barrier cream may prevent skin from the harmful effects of PM, but their effects are yet to be explored. ...
... 34,35 During the study period, the mean concentration levels of PM 10 To maintain skin barrier function, the use of moisturizing cream and cleanser is important. 29,30 Cleansers with micellar nanoparticles have both a hydrophobic part which entraps oil and a hydrophilic part which attracts aqueous solution, thereby forming micelle, which allows oil droplets to be effectively washed away. 40 As such, lower concentration of the surfactant can be used in micellar cleansers without the need for surfactants that are too strong, which may harm skin barrier function. ...
Article
Full-text available
While there is increasing interest in anti‐pollution care to particulate matter (PM), there has been no research evaluating the efficacy of skin care products in a real‐world setting. Our objective was to find effective ways to protect skin from PM. In total, 64 volunteers whose skin was classified as reactive to PM concentration in the previous study were enrolled. Through split‐face study, different combinations of skin care products (barrier cream, barrier cream/micellar water, antioxidant, and antioxidant/micellar water) were applied for 4 weeks during the high PM period. The biophysical properties were measured, and a facial analysis system was used to evaluate skin condition at days 0, 14, and 28. The concentrations of PM and daily events that may affect skin conditions were also recorded. The mean concentration levels of PM10 and PM2.5 from days 0 to 14 were higher in the barrier cream group than in the antioxidant group. For each group, aside from skin tone in the antioxidant/micellar water group, there were no statistically significant differences in skin measurements before and after the application which reflects no aggravation in skin condition during high PM periods. Intergroup analysis showed no differences in skin measurements among the four groups from day 0 to day 14, from day 14 to day 28, and from day 0 to 28. For anti‐pollution care, maintaining skin barrier function using barrier cream seems to be sufficient in individuals sensitive to PM. This article is protected by copyright. All rights reserved.
... Both formulations, shampoo and mousse, were well tolerated by all the treated dogsno side effects were observed by the investigators during the study. The negative impact of harsher surfactants on the skin barrier in some antiseborrhoeic shampoos is sometimes a concern for prescribers and users [43]. This action leads to a notable loss of lipids, most often related to the surfactants contained in certain products [44,45]. ...
Article
Full-text available
The study aimed to evaluate the tolerance, performance and effect on hair lipids and skin hydration of a protocol combining applications of one shampoo and subsequent mousses containing plant extracts (Ophytrium and Seboliance) in dogs with an undiagnosed chronic greasy keratinisation disorder. Six dogs were washed with plain water on day (D)0. Twelve dogs were shampooed on D0 and received eight mousse applications at 48–72 h intervals from D2 to D18. Clinical score (CS), Natural Moisturizing Factors (NMF) and hair lipids (HL) were evaluated on D0, D0 + 4 h, D7, D14 and D24. At baseline, no significant differences were observed in CS, NMF and HL between groups. In the control group, CS and HL remained stable throughout the study while a slight decrease in NMF was observed at D0 + 4 h. CS was significantly reduced in the test group between D0 and D7 (−53%) which reached 91% at D24 (p < 0.05), with no side effects. NMF levels decreased in the test group at D0 + 4 h (−73%, p < 0.0001) and returned to baseline from D14. In conclusion, one shampoo and subsequent mousse applications rapidly and safely improved coat quality in dogs with an undiagnosed keratinisation disorder without affecting NMF and HL contents over the study period.
... It is well known that body wash products can have a significant impact on skin conditions due to the effects of cleansing surfactants and skin conditioning agents. [28][29][30] For example, anionic and nonionic detergents present in the formulation are thought to have adverse effects on normal skin barrier functions and cause skin irritation and dry skin conditions. 31,32 On the other hand, some of the advanced body wash products are designed to deposit a meaningful amount of skin conditioning agents onto the skin during the cleansing process, which leads to significant improvement of dry skin conditions. ...
Article
Full-text available
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.
... In rinse-off products like shampoos and body washes, anionic surfactants are frequently utilized to assist cleaning. Anionic surfactants give these products the exceptional foaming and lathering qualities that consumers seek, although many surfactants are thought to be irritating to the skin 10,11 .Water contains nitrogen in the form of free ammonia (NH 3 ) and ammonium salts (NH 4 + ), which is referred to as ammonia nitrogen (NH 3 -N). The breakdown products of nitrogen-containing organic matter in domestic sewage by microbes, primarily from industrial e uent like coking and synthetic ammonia, account for a portion of the ammonia nitrogen in water [12][13][14] . ...
Preprint
Full-text available
The present study aimed to develop a method for the simultaneous determination of volatile phenol, cyanide, anionic surfactant, and ammonia nitrogen in drinking, ground and surface water, as well as in wastewater, using a continuous flow analyzer. Using on-line distillation, the distillate reacts with 4-aminoantipyrine in the presence of basic potassium ferricyanide, and the amount of volatile phenol is assessed using spectrophotometry. The distillate combines with chloramine-T and then with isonicotinic acid pyrazolone to generate blue chemicals through on-line distillation. The amount of cyanide is measured using spectrophotometry and extracted on-line, the amount of anionic surfactants was measured using methylene blue spectrophotometry and extracted on-line, and ammonia is reacting with salicylate and chlorine from dichloroisocyanuric acid to produce indophenol blue at 37°C in an alkaline environment and measured at 660 nm. The relative standard deviations were 0.75%~ 2.80% and 0.36% ~ 2.26%, respectively, and the recoveries were 98% ~ 103.6% and 101% ~ 102% when the mass concentration of volatile phenol and cyanide is 2 µg/L ~ 100 µg/L, the linear correlation coefficients are greater than or equal to 0.9999, and the detection limits are 1.2 µg/L and 0.9 µg/L, respectively. The relative standard deviations were 0.27% ~ 0.96% and 0.33% ~ 3.13%, and the recoveries were 94.3% ~ 107.0% and 98.0% ~ 101.7%. The mass concentration of anionic surfactant and ammonia nitrogen is 10 µg/L ~ 1000 µg/L, the linear correlation coefficients are 0.9995 and 0.9999, and the detection limits are 10.7 µg/L and 7.3 µg/L, respectively. This approach saves time and labor, has a lower detection limit, higher precision and accuracy, less contamination, and is more appropriate for the analysis and determination of large amounts of samples. When compared to the national standard method, the difference was not statistically significant.
... Indeed, it has been reported that the skin proteins swell markedly if exposed to highly alkaline substances (pH > 8.0). Optical coherence tomography (OCT) images of the stratum corneum (SC) [9] after its exposure to acidic (4.0), neutral (6.5), and alkaline pH (10.0) conditions, showed that there is significantly greater SC swelling when exposed to alkaline pH solutions, while acidic pH induces SC shrinking [10]. Alkaline pH also has an effect on SC lipids, with the ionization of fatty acids in the lipid bilayers causing the overall destabilization of the lipid bilayers [11]. ...
Article
Full-text available
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, KeraSkinTM, 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.
... These are ideal for liquid formulations that are sprayable because they do not undergo coalescence, flocculation, and sedimentation [50]. Nanoemulsions are thermodynamically stable; hence their formulations require low amount of surfactant (5-10%), otherwise some harsh surfactants may damage skin lipids and proteins causing dryness, irritation, and itching on skin [57,58]. During their applications in hair care products, they remove the brittleness and greasiness of hair making them smooth and shiny due to their Aggregates of thousands of atoms joined together to form a cluster with particle size in the submicron range of 100-1000 nm [145] Nontoxic, increase the solubility of substances, increase bioavailabilty [148] Not reported Not reported - Protect drug during storage, increase bioavailability of drug, controlled and sustained release [161,162] Productivity is difficult and costly at industrial scale, less ability to adjust the drug dose [267] Hydra Flash Bronzer Daily Face Eye Contour Nanolift [209] Moisturizer Antiwrinkle & Antiaging Nanogold Nanoparticles of metallic gold (5 nm-400 nm) [197] Biocompatible, easy penetration, dermo protective, photostable [198,202] Not [59,60]. ...
Article
Full-text available
In recent years, there has been a rising trend in using nanoscale materials to develop nanocosmetics. Several types of nanomaterials are of supreme interest for applications in the cosmetic industry, owing to their unique structural, chemical, physical, physiochemical, and functional features, which are mostly lacking in non-nanoscale counterparts. Regardless of the materials type, shape, morphology, and composition, there are two main uses of nanomaterials in cosmeceutical products, i.e., (1) nanoconstructs as ultraviolet (UV) filters and (2) nanoconstructs as bioactive agents for topical and other cosmeceutical related products, e.g., moisturizers, hair care products, skincare, makeup, sunscreen, etc. In the former case, several types of nanoparticles, e.g., silver, gold, titanium, and zinc, have been used as UV filters or UV protectants that block or absorb UV light to protect the skin from harmful effects. In the second scenario applications, nanoliposomes are used as delivery vehicles. Thus, nanomaterials enriched nanocosmetics have been identified as potential next-generation cosmeceutical products for a blooming beauty that provides improved skin hydration, bioavailability, stability of the agent, and controlled UV occlusion. In spite of several noteworthy applications, safety considerations and regulatory aspects of nanomaterials in cosmetic products cannot be ignored, which are mostly lacking in the existing literature. Therefore, considering the above potentialities of nanomaterials and critiques, herein, we first reviewed the valuable aspects of nanoparticles and nanoliposomes as UV filters and delivery vehicles. The second half of the work focuses on the safety considerations and regulatory aspects of nanomaterials used in cosmetic formulations. Finally, the work is summed up with concluding notes and recommendations for future research that will be helpful for the material scientists to safely exploit the nanomaterials in commercial scale products.
... Transient pH elevation after soap use causes a temporary decrease in barrier functions. 460,461 Moreover, additives in detergents, such as pigments and perfumes, are believed to cause skin irritation. Based on these results and the above studies, soap or cleanser may be useful for keeping the skin clean. ...
Article
This is the English version of the Clinical Practice Guidelines for the Management of Atopic Dermatitis 2021. Atopic dermatitis (AD) is a disease characterized by relapsing eczema with pruritus as a primary lesion. In Japan, from the perspective of evidence‐based medicine, the current strategies for the treatment of AD consist of three primary measures: (i) use of topical corticosteroids, tacrolimus ointment, and delgocitinib ointment as the main treatment of the inflammation; (ii) topical application of emollients to treat the cutaneous barrier dysfunction; and (iii) avoidance of apparent exacerbating factors, psychological counseling, and advice about daily life. In the present revised guidelines, descriptions of three new drugs, namely, dupilumab, delgocitinib, and baricitinib, have been added. The guidelines present recommendations to review clinical research articles, evaluate the balance between the advantages and disadvantages of medical activities, and optimize medical activity‐related patient outcomes with respect to several important points requiring decision‐making in clinical practice.
... 8 In contrast, soaps usually have pH of circa 11, which can cause skin dryness and irritation after frequent use. [7][8][9][10] For this reason, syndets can be considered more appropriate than traditional soaps for general skin cleaning products, especially for sensitive skins. An additional advantage of syndets over classical soaps is their increased compatibility with additives such as colorants, fragrances, and other property-enhancing compounds, 8,11 which are commonly used in the formulation of different cosmetic products but can be unstable in the alkaline pH conditions of soap. ...
Article
Full-text available
Soap bars offer a valuable alternative to liquid soaps and their market is flourishing in response to commitment to The Green Economy and sustainable products. The advent of synthetic detergent ( syndet) "soap" formulations has opened markets for products such as shampoo, conditioner and facial bars. However, their processability has revealed to be less controllable than conventional fatty acid-based soaps. In this work, we present a rheological characterization of a set of syndet formulations as a function of both their moisture content and of a compressional axial stress applied perpendicularly to the shear deformation, as experienced by the materials within extruders during the production process. The main outcome of our investigation reveals that syndet shows a significant stiffening when subjected to a compressional stress and a slight reduction of the yield stress as function of the moisture content. In particular, we report that, within the instrumental limits of applicable normal stresses (i.e. from ~1kPa to 300kPa), both the linear viscoelastic moduli of syndets and their yield stress increase by two orders of magnitude; thus, potentially explaining the difficulties encountered during their production.
... In addition, this work shows the necessity of lipids in not only preventing bacterial entry into the skin but also governing stratum corneum mechanical barrier integrity and fracture behavior. This is especially important for people that might be prone to lipid depletion through abnormalities in lipid-processing proteins (72), occupational hazards such as repeated hand washing required for sterile environments (73,74), or contact with metal working fluids, solvents, and caustic chemicals (75). Last, the connection between bacteria and immersion (natural moisturizing factors) could contribute to a lack of natural moisturizing factors observed in the stratum corneum of atopic dermatitis patients (76,77). ...
Article
Full-text available
Millions of people suffer from the chronic inflammatory skin disease atopic dermatitis (AD), whose symptoms are associated with a deficiency of skin lipids that exhibit antimicrobial functions and increased populations of the opportunistic pathogen Staphylococcus aureus . However, the pathogenesis of AD is ambiguous, and it remains unclear if these observed changes are merely the result of AD or contribute to the pathogenesis of the disease.
... Thanks to the amphiphilic structure, surfactants can be dissolved in both polar and apolar solvents. While detergents adhere to water molecules with their polar parts due to these chemical properties, they ensure the removal of dirt from the environment by holding on to the dirt with their apolar parts [10][11][12][13]. ...
Article
Full-text available
Background This study aimed to evaluate possible cytotoxic effects to gingival epithelial cells exposed to children toothpastes containing different detergent. Methods Tissues required for the isolation of human gingival epithelial cells were obtained by biopsy during the extraction of the impacted third molar tooth. Toothpaste solutions of different concentrations were prepared from five different children’s toothpastes with different detergent contents. Isolated gingival epithelial cells were stimulated with experimental groups consisting of toothpaste solutions (Colgate, Sensodyne, Splat, Nenedent, Perlodent) at different concentrations and a control group consisting of complete Dulbecco’s modified eagle medium. After the experiments, cell viability was evaluated using flow cytometry. 2 Way ANOVA was used to see the interaction effect of the main effects of toothpaste solution and concentration factors. Pairwise comparisons were made by Tukey post hoc tests. In the study, the significance level was taken as 0.05. Results As a result of the analysis, it was seen that the toothpaste solution and concentration factors and the interactions of these 2 factors were effective on the viable, early apoptotic, late apoptotic and necrotic cell rates. The statistically highest live cell ratios were detected in Splat’s toothpaste solutions (90.14% at 0.4% concentration) after the control group (90.82%) and the group with the lowest viability values was determined in Colgate group (75.74% at 0.4% concentration) (p < 0.05). Conclusions According to the results of the study, it was observed that toothpastes containing SLS affected the viability of cells more negatively than toothpastes with other detergent contents.
... The external layer of skin stratum corneum is composed of proteins (65-75%), lipids (10-15%) and water (15%) and renewed by epidermis continuously [1,2]. The capacity of skin barrier is related to the intracellular lipid molecular structure of stratum corneum [3]. ...
... For example, the use of soap stresses the stratum corneum by altering skin pH (acid mantle) to a more alkaline environment, disrupts transepidermal water loss, strips lipids, and removes natural moisturising factor, a chemical protective coat of the epidermis responsible for maintaining adequate hydration of the stratum corneum. 43 Device-related PI (DRPI) can account for a large proportion ICUacquired PI; however, prospective longitudinal data for DRPI in the ICU are limited. Apold and Rydrych 44 found that nearly a third (29%) of reported PI were caused by medical devices. ...
Article
Introduction Pressure injury (PI) is an ongoing problem for patients in intensive care units (ICUs). The aim of this study was to explore the nature and extent of PI prevention practices in Australian adult ICUs. Materials and methods An Australian multicentre, cross-sectional study was conducted via telephone interview using a structured survey instrument comprising six categories: workplace demographics, patient assessment, PI prevention strategies, medical devices, skin hygiene, and other health service strategies. Publicly funded adult ICUs, accredited with the College of Intensive Care Medicine, were surveyed. Data were analysed using descriptive statistics and chi-square tests for independence to explore associations according to geographical location. Results Of the 75 eligible ICUs, 70 responded (93% response rate). PI was considered problematic in two-thirds (68%) of all ICUs. Common PI prevention strategies included risk assessment and visual skin assessment conducted within at least 6 h of admission (70% and 73%, respectively), a structured repositioning regimen (90%), use of barrier products to protect the skin (94%), sacrum or heel prophylactic multilayered silicone foam dressings (88%), regular PI chart audits (96%), and PI quality improvement projects (90%). PI prevention rounding and safety huddles were used in 37% of ICUs, and 31% undertook PI research. Although most ICUs were supported by a facility-wide skin integrity service, it was more common in metropolitan ICUs than in rural and regional ICUs (p < 0.001). Conversely, there was greater involvement of occupational therapists in PI prevention in rural or regional ICUs than in metropolitan ICUs (p = 0.026). Discussion and conclusion This is the first study to provide a comprehensive description of PI prevention practices in Australian ICUs. Findings demonstrate that PI prevention practices, although nuanced in some areas to geographical location, are used in multiple and varied ways across ICUs.
... In particular, anionic surfactants are often found in combination with zwitterionic surfactants in liquid cleansing products. 1 Researchers have shown that this combination leads to reduced stratum corneum and protein swelling in vitro 2 as well as reduced erythema in vivo 3 compared to that induced by the anionic surfactant alone. Using a 4 h human covered patch test, Hall-Manning et al. demonstrated that binary surfactant systems, including an SDS/betaine mixture, produced less acute irritation than either of the constituents. ...
... [ 16] In the Indian scenario, vegetable oils are used extensively for baby massage and as moisturizers. Mustard oil is preferable for oil massage in newborn as it is timetested and owing to its small molecular structure, allows easy use and is ideal for dry skin. ...
Article
Full-text available
Skin of the newborn babies differs from that of an adult in several ways. Baby’s skin is more susceptible to trauma and infection and requires special care. As a parent, everyone wants best products for their child. That includes giving them the best skin care routine to keep baby skin soft and healthy. Some ingredients of baby products can cause sensitive skin to become irritated, and certain others can even be absorbed into little one’s body. For this reason, it’s important to know what ingredients are in the products you use on baby’s skin. Selecting safe and effective skin care products for your baby can be overwhelming, but it’s not impossible. Now a days, parents not easily pick up labels with trendy claims, such as “hypoallergenic, ” “gentle, ” or “organic, ” try learning about ingredients that can cause skin irritation if baby shows signs of a rash or reaction. Children are especially vulnerable to chemicals in baby shampoos, lotions, powders, ointments, baby wipes and many other products. Children’s brains, nervous systems and other body organs are still developing, and so these chemical substances that have a small effect on adults can contribute to developmental problems in children. Babies also ingest products that are meant for external use only by putting their fingers, hands, toes, toys and other objects into their mouths. Many personal care baby products contain “penetration enhancers” which further increase the absorption of chemicals through the skin. Some of the known health effects of the more harmful ingredients include developmental problems, cancer, reproductive problems, mutations, nervous system disorders, inflammation, allergy and even death. Other harmful ingredients may irritate the baby’s skin, eyes, respiratory tract or digestive tract. [13] So my aim to prepare a herbal oil formulation as baby product which may produce less or no harm on to the baby’s skin & help them to grow mentally and physically well & healthy.
... 9 The binding tendency of surfactants to proteins depends on their electrical charge, and it has been shown that this tendency is higher for anionic surfactants. 10 This study found the highest increase in TEWL in the traditional alkaline soap users, which has a high charge density of the carboxyl head group that promotes strong protein binding and causes barrier damage. ...
Article
Background While soaps are the most commonly used cleansing agents for human skin, they also damage the epidermal barrier and potentially increase the risk of disorders such as contact dermatitis. Aims This study set out to compare the potential skin irritancy of four types of soaps and their effects on the skin barrier function and biophysical parameters. Methods In a nonblinded comparative study, three types of soaps (alkaline, creamy, and glycerin soaps), and a syndet were applied to four different groups of 15 healthy subjects. Subjects washed their left forearm with the respective soap at home at least four times a day for seven days. Biophysical skin parameters, including transepidermal water loss (TEWL), erythema, friction, and pH, were measured at various time points using the Cutometer®MPA 580. Results After the first wash, a significant increase in TEWL was observed for all groups compared to the pre-intervention period. For the alkaline soap, a substantial increase in pH was observed at all time points compared to the baseline. Syndet, the only acidic soap in this study, showed a significant decrease in pH at the last time compared to all time points. The mean value of erythema was significantly higher in alkaline soap users than glycerin and creamy soap users. Conclusion Our study showed that alkaline-based soaps could cause erythema and increase TEWL and skin pH due to their strong cleansing action, and the addition of compounds such as glycerin can modify these effects. A newer generation of soap containing a mild surfactant such as syndets causes less skin damage.
... However, the repeated and prolonged interaction between these surfactants and the proteins or lipids of stratum corneum could weaken the skin barrier function. The consequences of skin barrier degradation might be the after-wash tightness, which consists in rapid evaporation of water from the skin surface causing tightness, itch, dryness, irritation, or inflammation [238,239]. Therefore, there is a need to develop cleansing systems that preserve and respect the skin barrier. The colloidal stability of cleansers is critical and thus the use of stabilizing agents is necessary. ...
Article
Full-text available
Calcium phosphates (CaPs) belong to a class of biomimetic materials widely employed for medical applications thanks to their excellent properties, such as biodegradability, biocompatibility and osteoinductivity. The recent trend in the cosmetics field of substituting potentially hazardous materials with natural, safe, and sustainable ingredients for the health of consumers and for the environment, as well as the progress in the materials science of academics and chemical industries, has opened new perspectives in the use of CaPs in this field. While several reviews have been focused on the applications of CaP-based materials in medicine, this is the first attempt to catalogue the properties and use of CaPs in cosmetics. In this review a brief introduction on the chemical and physical characteristics of the main CaP phases is given, followed by an up-to-date report of their use in cosmetics through a large literature survey of research papers and patents. The application of CaPs as agents in oral care, skin care, hair care, and odor control has been selected and extensively discussed, highlighting the correlation between the chemical, physical and toxicological properties of the materials with their final applications. Finally, perspectives on the main challenges that should be addressed by the scientific community and cosmetics companies to widen the application of CaPs in cosmetics are given.
... Thanks to the amphiphilic structure, surfactants can be dissolved in both polar and apolar solvents. While detergents adhere to water molecules with their polar parts due to these chemical properties, they ensure the removal of dirt from the environment by holding on to the dirt with their apolar parts [10,11,12,13]. ...
Preprint
Full-text available
Background: This study aimed to evaluate possible cytotoxic effects to gingival epithelial cells exposed to children toothpastes containing different detergent. Methods: Tissues required fort he isolation of human gingival epithelial cells were obtained by biopsy during the extraction of the impacted third molar tooth. Toothpaste solutions of different concentrations were prepared from five different children’s toothpastes with different detergent contents. Isolated gingival epithelial cells were stimulated with experimental groups consisting of toothpaste solutions (Colgate, Sensodyne, Splat, Nenedent, Perlodent) at different concentrations and a control group consissting of complete Dulbocco’s modified eagle medium. After the experiments, cell viability was evaluated using flow cytometry. Data analysis were done using One Way ANOVA test and Tukey post-hoc test. Results: In all experimental groups, there was a decrease in live cell rates and an increase in dead cell rates due to increased concentration. The statistically highest live cell ratios were detected in Splat’s toothpaste solutions after the control group and the group with the lowest viability values was determined in Colgate group (p<0.05). Conclusions: According to the results of the study, it was observed that toothpastes containing SLS affected the viability of cells more negatively than toothpastes with other detergent contents.
... Analogous tests are typically employed to compare the washing abilities of different detergents, so in addition to the mechanistic questions, they will provide reliable grounds for the comparison of the practical usefulness of SAP and its synthetic counterparts. Surfactants whose washing properties are too strong may not only remove dirt from the skin surface but also its protective hydro-lipidic layer, which may lead to excessive water loss by the skin and its excessive drying [15,46]. In this context, an ideal surfactant would show a minimum emulsification capacity towards the olive oil and a maximum one-towards the engine oil. ...
Article
Full-text available
Our skin is continuously exposed to different amphiphilic substances capable of interaction with its lipids and proteins. We describe the effect of a saponin-rich soapwort extract and of four commonly employed synthetic surfactants: sodium lauryl sulfate (SLS), sodium laureth sulfate (SLES), ammonium lauryl sulfate (ALS), cocamidopropyl betaine (CAPB) on different human skin models. Two human skin cell lines were employed: normal keratinocytes (HaCaT) and human melanoma cells (A375). The liposomes consisting of a dipalmitoylphosphatidylcholine/cholesterol mixture in a molar ratio of 7:3, mimicking the cell membrane of keratinocytes and melanoma cells were employed as the second model. Using dynamic light scattering (DLS), the particle size distribution of liposomes was analyzed before and after contact with the tested (bio)surfactants. The results, supplemented by the protein solubilization tests (albumin denaturation test, zein test) and oil emulsification capacity (using olive oil and engine oil), showed that the soapwort extract affects the skin models to a clearly different extent than any of the tested synthetic surfactants. Its protein and lipid solubilizing potential are much smaller than for the three anionic surfactants (SLS, ALS, SLES). In terms of protein solubilization potential, the soapwort extract is comparable to CAPB, which, however, is much harsher to lipids.
... However, while exerting their cleansing function, these substances can negatively affect the structural and functional integrity of the skin. Their damaging effects are the result of an increase in the skin surface pH (alkalization), excessive removal of skin structural components (lipids and proteins), stratum corneum damage and even cytotoxicity [88][89][90]. Their skin-irritation activity is related to interactions with skin components and depends on the surfactant's structure and physical properties in aqueous solutions [91]. A systematic review on the interactions between surfactants and the skin is given by Seweryn with a detailed discussion about surfactants' structure and properties and how they relate to skin damage [91]. ...
Article
Full-text available
Acidic pH of the skin surface has been recognized as a regulating factor for the maintenance of the stratum corneum homeostasis and barrier permeability. The most important functions of acidic pH seem to be related to the keratinocyte differentiation process, the formation and function of epidermal lipids and the corneocyte lipid envelope, the maintenance of the skin microbiome and, consequently, skin disturbances and diseases. As acknowledged extrinsic factors that affect skin pH, topically applied products could contribute to skin health maintenance via skin pH value control. The obtained knowledge on skins’ pH could be used in the formulation of more effective topical products, which would add to the development of the so-called products ‘for skin health maintenance’. There is a high level of agreement that topical products should be acidified and possess pH in the range of 4 to 6. However, formulators, dermatologists and consumers would benefit from some more precise guidance concerning favorable products pH values and the selection of cosmetic ingredients which could be responsible for acidification, together with a more extensive understanding of the mechanisms underlaying the process of skin acidification by topical products.
... It alters normal skin flora, aggravates skin dryness, and causes irritation, hence not preferred in atopic dermatitis. [22] It is recommended to use lukewarm water of temperature 27°C-30°C, in which the child should enjoy to play. There is no definite frequency or duration of bath that is truly optimal for atopic dermatitis. ...
Article
The diagnosis and management of atopic dermatitis are often challenging due to the complexity of its etiopathogenesis and the variety of presentation. Atopic dermatitis is one of the very prevalent dermatoses in which drug therapy alone will not suffice. However, it also requires a logical modification of the patient’s dayto-day activities and his microenvironment. For this, the patient has to understand the disease very well, and knowledge regarding the disease, conditions the patient, for the prolonged treatment course. Various nonpharmacological interventions play an important role in achieving this.
Article
Full-text available
This study developed a method for the simultaneous determination of volatile phenol, cyanide, anionic surfactant, and ammonia nitrogen in drinking water, using a continuous flow analyzer. The samples were first distilled at 145 °C. The phenol in the distillate then subsequently reacted with alkaline ferricyanide and 4-aminoantipyrine to form a red complex that was measured colorimetrically at 505 nm. Cyanide in the distillate subsequently reacted with chloramine T to form cyanogen chloride, which then formed a blue complex with pyridinecarboxylic acid that was measured colorimetrically at 630 nm. The anionic surfactant reacted with basic methylene blue to form a compound that was extracted into chloroform and washed with acidic methylene blue to remove interfering substances. The blue compound in chloroform was determined colorimetrically at 660 nm. Ammonia reacted with salicylate and chlorine from dichloroisocyanuric acid to produce indophenol blue at 37 °C in an alkaline environment that was measured at 660 nm. The relative standard deviations were 0.75–6.10% and 0.36–5.41%, respectively, and the recoveries were 96.2–103.6% and 96.0–102.4% when the mass concentration of volatile phenol and cyanide was in the range of 2–100 μg/L. The linear correlation coefficients were ≥ 0.9999, and the detection limits were1.2 μg/L and 0.9 μg/L, respectively. The relative standard deviations were 0.27–4.86% and 0.33–5.39%, and the recoveries were 93.7–107.0% and 94.4–101.7%. When the mass concentration of anionic surfactant and ammonia nitrogen was 10–1000 μg/L. The linear correlation coefficients were 0.9995 and 0.9999, and the detection limits were 10.7 μg/L and 7.3 μg/L, respectively. When compared to the national standard method, no statistically significant difference was found. This approach saves time and labor, has a lower detection limit, higher precision and accuracy, less contamination, and is more appropriate for the analysis and determination of large-volume samples.
Article
The components of a shampoo are selected specifically to carry out important roles within the formulation. They must be carefully considered as not only do they act to carry out their own function, but they also influence the function of the other components through complexation and other physio‐chemical interactions. This review focuses on the four principal components in a commercial shampoo formulation: surfactant, deposition polymer, structuring polymer, and viscosity modifiers. The most common molecule types used commercially to carry out the specific roles are discussed, with each of their fundamental functions outlined in detail. The mechanisms by which these molecules can perform these roles are reviewed. Further consideration is taken to outline how components could interact with one another to hinder or facilitate processes. This article is protected by copyright. All rights reserved
Article
Background: Different strategies for hand skin hygiene have been used to prevent the spread of SARS-CoV-2. However, frequent hand sanitization has been associated with skin damage. The present study aimed to evaluate hand hygiene habits during the COVID-19 pandemic and the effect of the repetitive use of soap or alcohol-based products on skin characteristics. Methods: We conducted a survey regards hand hygiene habits acquired during the COVID-19 pandemic. Also, we performed cutometry in a cohort of individuals who cleansed their volar forearms every 30 min, during 4 h, using soap or alcohol-based products. Results: We received 138 responses from people with medium-high educational level who reported a 2.5-time increase in the frequency of hand cleansing (p < 0.0001) that resulted in skin damage. An in vivo analysis of skin moisture and elasticity was also performed among 19 health workers and students. In general, skin moisture decreased with every cleansing, mainly after 2 h of washing with soap (p < 0.01), while skin elasticity only reduced after 4 h of treatment (p < 0.05). Alcohol-based solution or alcohol-based gel (70% ethanol, both) did not affect skin moisture or elasticity during testing. Conclusion: It is known that the excessive use of soap or alcohol-based products causes dermatological issues. The present study demonstrates that non-medicated soap significantly affects skin moisture and elasticity, probably because the soap removes the hydrolipidic protective barrier, favoring transepidermal water loss, where the lack of the appropriate stratum corneum hydration also affects skin elasticity, mainly associated with changes in epidermal structure.
Chapter
The prevalence of metabolic syndrome is increasing day by day, owing to the sedentary lifestyle, unhealthy food habits, genetic factors, environmental influences and many other conspicuous variables. Skin, aptly considered to be a mirror of internal organs, often manifests with certain signs and symptoms, suggestive of a diagnosis of metabolic syndrome. In this chapter, we have attempted to touch upon the dermatological manifestations (both common and uncommon) of metabolic syndrome.KeywordsMetabolic syndromeDiagnosisSkin manifestations
Chapter
Sensitive skin is characterized by abnormal and unpleasant sensations of burning, tingling, smarting or pricking, sometimes accompanied with redness, tightness or dryness of skin, after coming in contact with routinely used skin products or cosmetics. Syndet bar use leads to minimal or no skin irritation along with preservation of cutaneous protein, natural moisturizing factor and lipid content. Combination skin care regime, i.e., use of micellar water cleanser in morning, non-tinted cream with sunscreen in afternoon and serum in night, can help in reduction of sensitivity. Non-foaming cleansers are preferred choice in sensitive skin. Specially formulated anti-ageing creams containing sodium salicylates (1%), polyhydroxy and bionic acids are preferred in sensitive skin. Even the botanical or “natural” products can cause or precipitate sensitive skin symptoms. Powder-based cosmetics are safer in sensitive skin. Water soluble cosmetics with inert, hypoallergic, fragrance free, pure ingredients, specially formulated for sensitive skin should be used. Sunscreen with microfine zinc oxide or titanium oxide is preferred due to their inert and non-irritant nature. Nail polish with toluenesulfonamide-formaldehyde resin should be avoided. Individuals with sensitive or very sensitive skin may have impaired self-perception of social, physical and mental health. So, persistent symptoms may warrant psychological evaluation and counselling.
Article
Anionic surfactant penetration into the skin and their subsequent interactions with stratum corneum lipids and proteins has historically been linked with irritation and dryness from the use of soaps, body washes, facial cleansers, shampoos, and other rinse-off personal care products. Mechanisms of surfactant penetration into the skin surface has been a topic of debate for decades. In this review, we discuss relevant theories of surfactant penetration into skin as well as interactions of surfactants with skin components. We present evidence that thermodynamic analyses of surfactant solution equilibria can be useful in modeling these behaviors. A theory of surfactant monomer penetration into stratum corneum is proposed.
Article
Рост заболеваемости АД указывает на важную роль взаимодействия генетических факторов и факторов окружающей среды в развитии данного заболевания. Предположение, что первопричиной АД является нарушение эпидермального барьера, привлекло интерес исследователей к изучению генов, регулирующих барьерную функцию кожи. Наиболее существенные для патогенеза АД результаты показало исследование генов, кодирующих структурные белки эпидермального барьера, в ходе которого были выявлены наиболее значимые для заболевания генетические факторы, а именно мутации с потерей функции гена FLG, кодирующего профилаггрин, предшественник структурного белка филаггрина. Значение филаггрина в восстановлении поврежденного эпидермального барьера во многом зависит от его ведущей роли в образовании естественного увлажняющего фактора, влияющего на способность кератиноцитов удерживать воду и поддерживать баланс уровня рН. В результате активных поисков средств, стимулирующих выработку филаггрина, в терапевтическом арсенале появился филагринол – комбинация растительного масла проросших зерен пшеницы, оливкового масла и масла сои. The increase in the incidence of AD indicates the important role of the interaction of genetic factors and environmental factors in the development of this disease. The assumption that the root cause of AD is a violation of the epidermal barrier has attracted the interest of researchers in the study of genes that regulate the barrier function of the skin. The most significant results for the pathogenesis of AD were obtained from the study of genes encoding structural proteins of the epidermal barrier, during which the most significant genetic factors for the disease were identified, namely, mutations with loss of function of the FLG gene encoding profilaggrin, a precursor of the structural protein filaggrin. The importance of filaggrin in the restoration of the damaged epidermal barrier largely depends on its leading role in the formation of a natural moisturizing factor that affects the ability of keratinocytes to retain water and maintain pH balance. As a result of an active search for agents that stimulate the production of filaggrin, filagrinol appeared in the therapeutic arsenal – a combination of vegetable oil of sprouted wheat grains, olive oil and soybean oil.
Chapter
This chapter provides an overview of the many specialty facial cleanser technologies available; recommend which technologies are best suited to each skin type and cleansing need. It also provides an in‐depth understanding of substrate‐based facial cleansers. The mechanisms by which cleansing is accomplished can be grouped into three main categories: cleansing by chemistry; cleansing by physical action; and in many cases, cleansing by a combination of both chemistry and physical action. The introduction of moisturizing lathering cleanser is one of the most significant changes to affect the skin cleansing market in recent years. Emollient cleansers are a milder alternative to lather cleansers. Toners are a class of facial cleansers formulated to clean skin and minimize the appearance of pores. Dry cleansing cloths are disposable cloths that have lathering surfactants dried onto the cloths during the manufacturing process. Cleansing devices were introduced to patients and are motor‐powered implements with a very soft brush head.
Chapter
The outermost structure of the epidermis is the stratum corneum, and it forms the epidermal permeability barrier which prevents the loss of water and electrolytes. Corneocytes are formed by the terminal differentiation of the keratinocytes from the granular layer of the epidermis. Lamellar granules or bodies (LG or LB) are specialized lipid carrying vesicles formed in suprabasal keratinocytes, destined for delivery of the lipids in the interface between the corneocytes. Keratohyalin granules are irregularly shaped granules present in the granular cells of the epidermis, thus providing these cells the granular appearance. Epidermis also generates a spectrum of antimicrobial lipids, peptides, nucleic acids, proteases, and chemical signals that together forms the antimicrobial barrier. Epidermal lipids, the integral components of the permeability barrier, are synthesized and secreted by the keratinocytes in the stratum granulosum after processing and packaging into the LB. The human skin is constantly exposed to hostile environment.
Chapter
Atopic dermatitis is a complex disease process requiring a multifactorial approach in managing baseline disease, responding appropriately to flares, and optimizing preventative measures. This chapter reviews the role of bathing practices, topical anti-inflammatories, and topical antimicrobials in such management. Bathing practices, including frequency, duration, use of additives, and choice in cleansers/soaps, can improve or worsen the epithelial barrier. Although data are mixed and recommendations vary by organization and region, we recommend daily bathing in lukewarm water for less than ten minutes using neutral to mildly acidic non-soap cleansers, followed by the immediate application of emollients. Topical anti-inflammatories include topical corticosteroids, topical calcineurin inhibitors, and phosphodiesterase-4 inhibitors. Topical corticosteroids are the standard therapy for acute flares and patients who have failed conservative management with emollient alone. Providers must be astute in their utilization and optimize dosing, application vehicle, frequency, duration, and body location, to maximize benefit while minimizing potential side effects. Topical calcineurin inhibitors represent a steroid-sparing alternative that can be used for patients who require application to sensitive areas such as the face, eyelids, or genitalia, or who have developed side effects from or failure to respond to topical corticosteroids. Phosphodiesterase-4 inhibitors are a newer steroid-sparing alternative also to be considered. Topical antimicrobial methods include judicious utilization of topical antibiotics and the use of dilute bleach baths for prevention/decolonization. The data on the benefit of such methods are mixed, but they can be considered adjunctive therapy in those patients with frequent disease flares.
Article
Full-text available
The article provides information about the features of the structure, development and differentiated approach to the appointment of dexapanthenol preparations used for the prevention and complex treatment of skin diseases in children of wounded age. Regular use of leave-on cosmetic products including body creams and lotions is very high among children aged 0–4 years. However, in most cases, recommendations for the use of topical baby skin care medicinal products and/or cosmetic products are based not on scientific evidence, but on common sense, expert opinions, advertising, personal preferences of parents, pharmacists, dermatologists and/or pediatricians. For example, adsorbing properties of baby powders are insufficient, and after absorbing moisture, they actually turn to “urine compresses” that aggravate the epidermis injury. After swelling, the starch-containing powders represent an excellent growth media for pathogenic and opportunistic microflora. It is noted that only proper skin care for young children allows you to preserve its integrity and functional state. Special attention is paid to the preparations of the Bepanten® series in the form of cream and ointment, which meet all the criteria for topical products, and can be used for the prevention and treatment of skin diseases in young children, effectively protecting the skin from irritants, promoting its healing and recovery, having an anti-inflammatory effect, increasing its elasticity, elasticity and are recommended for use as a means of basic care. Their effectiveness has been repeatedly confirmed in the numerous domestic and foreign randomized controlled studies in new-born populations at different gestational ages, which provided the scientific justification for their common use in the ‘real-life’ practice of pediatricians, dermatologists and allergists.
Article
The aim of the study was to evaluate the effects of hydrophilic microcrystalline cellulose, hydrophobic talc and mixtures of cellulose and talc when used as fillers in powdered bath cosmetics. A number of model formulations were developed that contained fillers in different compositions. Prototypical formulations were prepared and evaluated for their functional properties and skin-drying effect. An increase in the concentration of talc was found to reduce the ability of the formulations to emulsify fatty soils and, consequently, decrease the skin-drying effect after washing. Another result of the study is that a high content of talc does not significantly impair the foaming ability, and the presence of talc improves the stability of generated foam.
Article
Full-text available
Objective Evaluate the effectiveness of a children's soap with physiological pH in maintaining cutaneous pH and moisture of the newborn (NB)’s skin after the first bath. Methods Randomized, controlled and double-blind clinical trial in a rooming-in of a tertiary maternity hospital in southern Brazil with 204 newborns > 34 gestational weeks. Gestational and obstetric history was evaluated, and newborns were randomized into two groups according to the product applied in the bath: the control group (CG), which used common liquid soap with pH 7.0 and experimental group (EG), which used children's liquid soap with pH 5.8. Evaluation was made immediately before and after bath with skin pH measurement, corneometry and clinical parameters (erythema, scaling and moisture), on the forehead, abdomen and thigh. Results There was no difference between groups regarding gestational, obstetric and family history (p > 0.05). In CG, skin pH increased in the abdomen and thigh (p < 0.05). In EG there was an improvement in clinical parameters after bathing with: increased moisture, less erythema and less scaling (p < 0.05). On the forehead, there was a significant increase in pH after bathing (p < 0.001) similar in both groups, although no use of soap. There was no difference in corneometry between groups after bathing. Conclusion Children's liquid soap with physiological pH maintained the acidic skin pH and moisture of the newborn's skin after the first bath, which reinforces the importance of using products with physiological pH in the hygiene of newborns. Registration number RBR-9ky84vd.
Chapter
Hair is biologically diverse with a range of textures and thicknesses. Hair also serves as expression of oneself; leading to hair care practices and styling that are influenced by culture, perception of beauty, and environment. The use of hair oils, styling and hair restructuring processes are utilized to help manage and style hair, along with offering options for self-expression. These hair care practices can lead to a range of complications, including contact dermatitis, seborrheic dermatitis, and scarring alopecias.
Article
Background New technologies, such as sonic devices, have been developed to optimize the skin cleansing process and improve its efficiency. To evaluate the effectiveness of these cosmetic procedures, skin bioengineering is an objective method to assess the biophysical parameters of the skin. Objectives This study aimed to assess the effect of facial cleansing on the physiological properties of the skin by comparing a cleansing process with cosmetic product applied manually to cleansing with cosmetic product associated with the use of an electric sonic device. Methods A gentle skin cleanser was applied to the entire face of 12 subjects; the sonic device was used on one half of the face and the manual process was performed on the other half. Instrumental skin analyses included sebummetry, corneometry, transepidermal water loss (TEWL), infrared thermography, and high‐frequency ultrasound and were measured before and up to 90 minutes after cleansing. Results were compared using two‐way ANOVA and Friedman tests. Results Data obtained from the statistical analysis of sebummetry, TEWL, thermography and ultrasound parameters did not show any significant difference. When assessing the corneometry parameters, a significant reduction in hydration values (17.19%) was observed in the manual cleansing area, while the values remained similar to baseline values in the area where the sonic device was used. Conclusion The cleansing process with a sonic device did not cause a significant hydration reduction, suggesting better preservation of skin homeostasis when compared to manual cleansing.
Article
Full-text available
A comparative analysis of surface and ultrastructural changes in stratum corneum (SC) with transepidermal water loss (TEWL) was conducted to develop a better understanding of the surfactant-induced damage to human skin. Treatments comprised a synthetic anionic surfactant (A), a composition of soap, glycerin, and petrolatum (B), a pure soap (C), and water (control). An increase in water loss is shown to correlate with increased perturbation of lipid barrier and damage to multiple layers of corneocytes. Transmission electron microscopy (TEM) revealed that, in general, one to two layers of lipid lamellae enveloped the outer layers of SC throughout the tissue. A significantly larger number of lamellae (approximately six to eight) appeared only in the lower layers. Surface topology, obtained using environmental scanning electron microscopy (ESEM), displayed a normal unperturbed structure. Treatment with A did not result in significant changes in SC. B caused regional variations in corneocytes and an increase in TEWL. Treatment with C exhibited significant variation in TEWL numbers: lipid lamellae were disordered and corneocytes appeared damaged and swollen. Intercorneocyte damage ranged from one to two (for TEWL ∼ 11 g/m2 hr) to up to six cell layers (for TEWL ∼ 34 g/m2 hr) of the SC. The presence or absence of the outermost layers of disjunctum did not appear to be critical for water loss, presumably due to a decrease in lipid lamellae.
Article
Full-text available
The gas-bearing electrodynamometer (GBE) (1) has been used for the last 20 years to obtain sensitive measurements of the stratum corneum. A new instrument for measuring the mechanical properties of the stratum corneum incorporates all of the measurement principles of the GBE but none of its components. A force-controlled miniature d.c. servo, gearing, and leadscrew replace the magnet/solenoid arrangement of the GBE. Error resulting from conversion of an electrical signal to a mechanical force is automatically compensated. Consequently, this control renders the need for a friction-free bearing redundant. The orginal linear variable differential transformer (LVDT) has been replaced with a unit with a sensitivity of 0.01%, and force is now measured by a calibrated 50-g load beam. The function generator, signal conditioner, and storage oscilloscope have been replaced by user-friendly software run by a small portable computer. The new design offers greater inherent accuracy than the GBE and requires minimal servicing. The new instrument (linear skin rheometer, "LSR") has been shown to provide sensitive measurements of stratum corneum mechanics and was used to measure the mechanical responses of the stratum corneum to two topical moisturizing treatments of differing relative hydration performance (as determined by impedance measurements using the Nova™ DPM9003). The relative performance of the two products as measured by the LSR compared favorably with corresponding impedance data, indicating the ability of the LSR to differentiate varying degrees of stratum corneum plasticization in response to hydration.
Chapter
Historically, the primary purpose of cleansing has been to achieve cleanliness and freshness by removing oily soils from face and body. Hygienic bene?ts of cleansing have also been recognized for a very long time. While soap-like materials for cleansing have been around as early as 2500 BC [1], soap itself is believed to have been invented sometime around 600-300 BC [2]. The first industrial type manufacturing of soap in an individually wrapped and branded bar form was in 1884 in England [2]. The desire for cleanliness and freshness coupled with the sensory pleasures and health benefits has driven the growth of soap in the 20th century [3]. Thus, deodorant soaps grew from a desire for health and hygiene bene?ts. The beauty segment, on the other hand, grew from a desire for beautiful skin coupled with the sensory pleasures of cleansing using cleansing bars of different colors, fragrances, and shapes [3].
Conference Paper
The manner in which ionic and non-ionic surfactants interact with skin is believed to depend upon their polar and non-polar moieties. Polar 'headgroups' of surfactants are expected to predominantly interact with hydrophilic domains of proteins. Non-polar 'tails' of surfactants are likely to cause disruption in the periodicity of skin's lipid lamellae as well as the hydrophobic domains of cellular proteins. Surfactant induced ultrastructural changes in proteins and lipids can be analyzed by transmission electron microscopy (TEM). Here, we first describe the qualitative changes in the lipids and proteins as a result of treatment of skin with various types of surfactants. Also included are recent studies to perform quantitative image analysis of lipids to determine the extent of lipid coverage of cells and lamellar packing. The structural changes were confined to the outer layers of corneocytes for skin treated with non-ionic surfactants. The structure of lipids around desmosomes and comeocytes was severely affected. Lipid lamellae, which generally span the inter-corneocyte region, appeared pooled and disordered. The cell envelope or inter-cellular proteins were not affected. However, the damage was limited only to the surface layers of comeocytes. For ionic surfactants, the TEM analysis revealed that the lamellar periodicity of the lipids was completely disrupted, the interior of the comeocytes showed gross damage to protein, and the cells appeared at least four times larger in projection. The depth of ultrastructural damage was directly related to the increase in trans-epidermal water loss (TEWL). The damage was confined to surface layers of comeocytes for regions where TEWL changed the least, but extended to 4-6 cell layers for areas that showed high change in TEWL. Ultrastructural analysis of skin, treated with mixtures of mild-anionic surfactants and cosurfactants showed preservation of multi-layered lipid lamellae and cellular proteins. Structural changes in lipids were further analyzed by quantifying: i) the proportion of comeocyte surface covered by inter-cellular lipid and ii) lipid order parameters by performing Fourier analysis of micrographs of lipid lamellae. Our preliminary analysis shows that these methods should allow us to perform more rigorous quantitative tests to determine the effect of surfactant containing products on skin.
Article
Synopsis Various clinical procedures exist for determining the mildness of personal washing products. It is common to use several of these evaluation methods in the development of a safety-and-claim support package. The utility of many of the methods is limited by their susceptibility to fluctuations in weather conditions. In this paper we describe a method, the flex wash test, which is not affected by changes in weather and can be used as a highly reproducible method for determining the relative irritancy potential of personal washing products. The flex wash test consists of a sixty-second wash, three times daily, of the antecubital fossa (flex area) of the arm. Washing is conducted for five consecutive days or until a moderate erythemic response is elicited. Erythema is assessed prior to each wash and four hours after the last daily wash. Twelve commer-cially available personal washing bars were evaluated in this study. The flex wash is a reproducible clinical test that distinguishes differences in the relative irritancy potential of various syndet (synthetic detergent) and soap bars and is independent of ambient weather conditions.
Article
This paper reports daily and seasonal patterns of lighting use in offices where occupants were able to vary the level of illuminance falling on their working areas. The results show that occupants set a wide range of illuminances, many of which are significantly below CIBSE Code recommendations leading to significant energy savings throughout the year. Although users report use of controls for a variety of reasons, the results of the long-term monitoring of switching behaviour reveals that very few in fact use them for anything other than to switch on upon arrival at work, with further use of systems during the day being rare. Evidence suggests that the way in which systems are configured exerts influence over the level of electric light occupants work under. There is some evidence of an effect of daylight availability on levels set but little evidence to suggest pervasive and consistent user preferences for levels of electric light.
Article
Synopsis Use was made of radiotagged SODIUM LAURYL SULFATE (SLS) to determine its sorption by skin and hair. In the initial stages uptake is linear in square root of time, indicative of a diffusion process. The uptakes determined by radiotagged SLS were successfully correlated with data from a simple gravimetric method and showed that the latter procedure can be used satisfactorily under certain conditions when radiotagged com- pounds are not available. The influence of some additives on the SORPTION of SLS was studied. Salt increases the sorption, while nonionic SURFACTANTS (which are not themselves sorbed) substantially depress it. Finally, the relation of the sorbed SLS to water of hydration of KERATIN is examined. It is con- cluded that most, if not all, the sorbed material is bound to keratin, rather than existing in an "internal" solu- tion.
Article
a series of pure SURFACTANTS. Effects of these compounds upon the STRATUM CORNEUM have been studied by means of KERATIN denaturation and the extraction of PROTEINS and AMINO ACIDS. It was found that strongly ANIONIC SURFACTANTS, such as sodium LAURYL SULPHATE, sodium LAURYL ETHER SULPHATE and sodium LAUROYL ISETHIONATE (Igepon A) had considerable activity, by virtue of their polar head groups, whereas sodium laurate and non-ionic ethoxylates had minimal effect upon the stratum corneum. The effect of lipophilic chain length of the surfactants was important in their overall activity, in particular, the lauryl moiety. PERCUTANEOUS ABSORPTION of RADIOACTIVELY-LABELLED surfactants by guinea-pigs in vivo has been studied; sodium laurate and lauryl triethoxylate penetrated to a far greater extent than other compounds: lauryl hexaethoxylate, sodium lauroyl isethionate and sodium lauryl triethoxy sulphate, had lower penetrabilities and sodium lauryl sulphate and sodium LAURYL SULPHONATE were lower still. The effect of pure surfactants upon living cells was studied by means of measuring HISTAMINE release from rat peritoneal MAST CELLS in vitro. ALKYL SULPHATES, ALKYL ETHER SULPHATES and alkyl tri- and hexaethoxylates were potent mast cell lysins, whereas monoethoxylate and sodium laurate and sodium lauroyl isethionate were less effective. Chain-length studies showed that the capryl, lauryl- and myristyl moieties were the most potent lipophilic groups for releasing histamine. Some of these surfactants were applied directly to the skin of RATS and the overall skin response determined by visual examination. Sodium laurate caused erythema after 24 h applica-
Article
in the lower stratum comeurn but underwent degradation towards the upper surface of the stratum corneum. These observations contrasted with xerotic skin, which had disorganized lipid bilayers in the upper stratum corneum, although apparently normal lipid bilayers in the deeper tissue regions. Also, desmosomes remained undegraded in the upper layers of the xerotic stratum corneum, a finding corrobo- rated by western blotting showing increased levels of desmoglein 1. Chromatographic analysis of stratum comeurn lipids showed decreased ceramide and increased fatty acid levels in subjects with xerosis compared with normal individuals, particularly in the outer stratum corneum layers. Although ceramides were lost from the stratum comeurn, the increased levels of fatty acids may be due in part to the deposition of soap fatty acids. Our results support previous studies demonstrating the importance of desmosomal degradation in desquamation. Furthermore, we have been able to show changes in the normal membrane structure of intracellular lipids in the desquamating layers of the stratum comeurn. These studies also provide new insights into soap-induced winter xerosis, revealing abnormalities in stratum comeurn lipid composition and organization together with reduced desmosomal degradation.
Article
The alterations caused by different surfactants in the permeability of liposomes formed by a lipid mixture that models the stratum corneum (SC) composition (40% ceramides, 25% cholesterol, 25% palmitic acid, and 10% cholesteryl sulfate) were investigated. The surfactant/lipid molar ratios (Re) and the bilayer/aqueous phase surfactant partition coefficients (K) were determined at two sublytic levels. The selected surfactant were sodium dodecyl sulfate (SDS); sodium dodecyl ether sulfate (SDES) to assess the influence of the ethylene oxide groups on the anionic surfactant’s behavior; Triton X-100 (OP-10EO) and dodecyl betaine (D-Bet) as representatives of nonionic and amphoteric surfactants. Permeability alterations were determined by monitoring the increase in the fluorescence intensity of liposomes due to the 5(6) carboxyfluorescein (CF) released from the interior of vesicles. The SC liposomes/surfactant sublytic interactions were mainly ruled by the action of surfactant monomers. OP-10EO showed the highest ability to alter the permeability of bilayers and the highest affinity with these structures, whereas D-Bet showed the lowest tendencies. Although SDS and SDES exhibited similar activity at 50% CF release (similar Re values), SDES appeared to be more active at 100% CF release, its affinity with bilayers being also increased. The different ability exhibited by SDS, SDES, and D-Bet (same alkyl chainlength) to alter the permeability of SC liposomes emphasizes the role played by the polar part of these surfactants in this interaction. Different trends in the evolution of Re and K were observed when comparing the results with those reported for phosphatidylcholine (PC) liposomes. Thus, whereas SC liposomes appeared to be more resistant to the action of surfactants, the surfactant affinity with SC bilayers was always greater than that reported for PC bilayers.
Article
The temperature-induced variation of several spectral features such as those shown above illustrates the power of IR spectroscopy for the study of lipid structure and organization in ceramides and models for the stratum corneum. Because the various spectral parameters monitor diverse aspects of molecular structure, a rather detailed picture of the structural organization that exists in both the polar and nonpolar regions of the molecules is acquired. In future applications, it is evident that the ability to monitor these changes in a detailed way will be extended to more complex experimental paradigms such as the normal and pathologic states of the stratum corneum.
Article
The physico-chemical and biological properties of an amphoteric/anionic system and its behaviour against a proteinic support have been thoroughly investigated. A considerable inhibition of adsorption of SLS (sodium lauryl sulphate) on human callus caused by the presence of definite amounts of AABet (alkyl-amido-betaines) in the treatment bath is observed. These physico-chemical results are in agreement with those obtained by some in vivo biological tests. A mechanism of the process via the formation of mixed micelles is postulated emphasizing the stability of such systems as a function of pH, the influence of the chain length of the amphoteric surfactant and the molar relative ratio SLS/AABet. Consequently, our work offers the possibility of a wide applicability of the synergic mixtures of both types of surfactants to inhibit considerably skin irritation of cosmetic finished products. Dans le présent travail on a étudié les propriétés physico-chimiques et biologiques des systèmes amphoteres/anioniques et leur comportement vis á vis d'un support proteinique. On observe une considérable inhibition de l'adsorption de SLS (lauryl sulphate de sodium) sur stratum corneum humain, causée par la présence de quantités definies des AABst (alkyl-amido-betaines) dans le bain de réaction. Les résultats physico-chimiques obtenus sont en accord avec les tests biologiques in vivo. On postule un mécanisme du processus basé sur la formation des micelles mixtes, remarquant la stabilité de ces systhèmes en fonction du pH, de l'influence de la longueur de chaine de l'agent de surface amphoterique et de la relation molaire SLS/AABet.
Article
An attempt to determine protein denaturing potency of typical surfactants has been made by measuring specific rotation of bovine serum albumin. The potencies obtained were examined in relation to the intensities of skin roughness in vivo caused by the surfactants, and a noticeable correlation was found between them. This fact also suggested that the cause of skin roughness may be attributed to a certain extent to adsorption of surfactants. In addition, this technique is very useful in predicting the skin roughening potency of a surfactant without using human skin.
Article
The chamber test for assessing the irritancy of soaps entails five weekday exposures to 8% solutions with readings of scaling, redness, and fissuring on the following Monday. Eighteen well-known toilet soaps were evaluated. Great differences were noted. Most had an appreciable irritancy potential. These results contrast with a number of studies which failed to show differences among soaps or which concluded that soaps were innocuous.
Article
The relationship between the in vivo irritation potential of sodium lauryl sulfate (SLS) and linear alkyl benzene sulfonate (LAS) and the ability of these two surfactants to remove lipid from the stratum corneum (SC) in vitro were investigated. Either surfactant removes detectable levels of lipids only above its critical micelle concentration (CMC). At high concentrations the surfactants removed only very small amounts of cholesterol, free fatty acid, the esters of those materials, and possibly squalene. SLS and LAS have been shown, below the CMC, to bind to and irritate the SC. Thus, clinical irritation provoked by SLS or LAS is unlikely to be directly linked with extraction of SC lipid. The milder forms of irritation--dryness, tightness, roughness--may involve both surfactant binding to and denaturation of keratin as well as disruption of lipid. Our findings challenge earlier assumptions that surfactants' degreasing of the SC is involved in the induction of erythema.
Article
In order to further clarify the role of intercellular lipids in the water-retention properties of the stratum corneum, forearm skin of six healthy male volunteers was treated with 5% sodium dodecyl sulfate (SDS) for 1, 10, and 30 min. All treatment periods induced chapping and scaling of the stratum corneum without any inflammatory reaction, accompanied by a significant decrease in its water-retention function. Electron-microscopic analysis of SDS-treated stratum corneum revealed selective depletion of the lipids from the intercellular spaces, accompanied by marked disruption of multiple lamellae structures. Lipid analysis also showed a considerable and selective loss of intercellular lipids such as cholesterol, cholesterol ester, free fatty acid, and sphingolipids. To evaluate the recovery potential for intercellular lipids, lipids which were separated as sebaceous-rich lipids (SLs) and stratum corneum lipids (SCLs) were applied daily on SDS-treated forearm skin. Two daily applications of the SCLs which were emulsified at 10% concentration in W/O (water in oil) cream caused a significant increase in conductance, accompanied by a definite improvement in the level of scaling over no application or W/O emulsion base only, whereas SLs in the W/O emulsion base led to no significant recovery in either conductance value or scaling. When two daily topical applications of four chromatographically separated lipid fractions (cholesterol ester, free fatty acid, cholesterol, and sphingolipid) from the SCL were carried out at 1% concentration in the same system, the cholesterol ester and sphingolipid fractions were found to induce a significant increase in the conductance value over no application.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
In order to clarify the possible role of lipids in the water-holding property of stratum corneum, the forearm skin of 6 healthy male volunteers was treated with acetone/ether (1/1) for 1, 5, 10, and 20 min. A prolonged treatment period of 5-20 min produced a chapped and scaly appearance of the stratum corneum without any inflammatory reactions. Under these conditions, there was a marked decrease in the water-holding capacity of the stratum corneum accompanied by a considerable and selective loss of intercellular lipids such as cholesterol, cholesterol esters, and phospholipids. These impairments persisted until day 4 after treatment. Electron microscopic observation of the altered stratum corneum revealed that naturally occurring intercellular materials were absent, leaving the area with the appearance of a vacant space. These findings suggest an additional and essential role of the specific structural lipids for the water-holding properties of the stratum corneum.
Article
Epidemiologic studies indicate that after using soaps and other personal care products, many consumers experience irritation. In 50% of the cases the feelings of skin dryness, itching, and stinging occur in the absence of visible signs of irritation. We sought to determine the relation between self-perceived sensory responses of panelists to cleansing products and clinical signs of irritation. A combination of exaggerated arm-washing methods was designed to induce clinical signs of irritation with psychometric techniques developed to quantify sensations. Two studies demonstrated that panelists could reproducibly differentiate between products on the basis of the sensations they felt and that there was a significant correlation (frequently r > 0.80) between these and the observable signs. In the case of skin dryness panelists differentiated products several washing cycles before observable differences were detected. Sensory evaluations of irritation yield additional information on soap and detergent irritancy beyond clinical observations and expand understanding of the irritation process.
Article
Corneosurfametry is introduced as a noninvasive quantitative test rating the interaction between surfactants and human stratum corneum. It may be used as a predictive irritancy test. Surfactants present in personal-care products elicit multiple effects on the stratum corneum. With upcoming regulations avoiding animal experiments and ethical considerations for human testing, there is a need for new in vitro methods evaluating irritancy. Corneosurfametry entails collection of cyanoacrylate skin surface strippings and short contact time with surfactants followed by staining samples with toluidine blue and basic fuchsin dyes. Measurements are made by reading the color of samples using reflectance colorimetry. The intensity of color increases with irritancy potential of the surfactant. Results are reproducible, and great differences are noted among a series of diluted shampoos, shower gels and facial cleansing gels. Corneosurfametry is proposed as a rapid in vitro method allowing a predictive grading of surfactants related to irritancy.
Article
After repeated contact, many surfactants will cause skin irritation and, especially, dryness and scaliness. Earlier in vitro investigations suggested that the irritation potential of anionic surfactants was related to the induction of hydration of isolated stratum corneum membranes. We have now investigated early surfactant – stratum corneum interaction in vivo. Sodium salts of n-alkyl sulfates with variable carbon chain length (n = 8–14) were tested for the promotion of stratum corneum hydration by measurements of skin surface water loss and electrical capacitance measurements in healthy adult human volunteers. The surfactant-induced increase in water uptake was confirmed in vitro by means of isolated stratum corneum samples and surfactant solutions labeled with tri-tiated water. In a parallel experiment the irritation potential of these compounds was investigated by 24-h patch testing in human volunteers. The irritant responses were quantified non-invasively by erythema (skin color reflectance measurements) and transepidermal water loss measurements. Hydration of stratum corneum exposed for 5 mm to factant solutions significantly exceeded that of controls (phosphate-buffered saline). It increased with application time and was concentration dependent, saturable with increasing concentration, and rapidly reversible. Baseline hydration was reestablished only 10–15 mm after treatment termination. Induction of hydration was closely correlated with the irritation potential of the investigated compounds. It initially increased with increasing carbon chain length. The maximum response was obtained for the C12 analogue (sodium lauryl sulfate). With further increases in molecular size induction of stratum corneum hydration subsequently decreased. We have demonstrated that anionic surfactants increase stratum corneum hydration in vivo. The present results suggest that the mechanisms responsible for the hydration are related to the irritation properties of these compounds.
Article
Synthetic detergents produce deleterious effects on human skin as the result of being taken up by the stratum corneum (SC). The present study aimed to determine to what extent a typical detergent enters the SC lipid lamellae, and what effect this might have on the physical properties of the lipids. These effects were studied in large unilamellar liposomes prepared from SC lipids (50% by weight of epidermal ceramides, 28% cholesterol, 17% free fatty acids, and 5% cholesteryl sulfate) by extrusion through successive polycarbonate filters of decreasing pore size, finally 400 nm. Freeze-fracture electron microscopy and light-scattering particle size analysis indicated a uniform liposome diameter averaging 230 nm. Partitioning of sodium dodecyl sulfate (SDS) into the lipid phase from aqueous buffer solutions was measured using the SC lipid liposomes and [U-14C]SDS. The partition coefficient was 416, 450, and 588 at pH 8.5 and 524, 507, and 807 at pH 7 for three different concentrations (0.1%, 0.02%, and 0.004%) of SDS. This high degree of partitioning into the liposomes is consistent with the high level of SDS partitioning seen in full SC. At the maximum, the SDS represented 18% of the liposomal lipids. Preparation of stable liposomes from SC lipids to which 10% or 20% of SDS had been added confirmed the ability of the liposomes to survive these high concentrations of surfactant. The permeability of the liposomes was enhanced as a result of SDS partitioning into the bilayers, as measured by the increased release of trapped [U-14C]glucose from these vesicles, and by their increased permeability to water in osmotic shock experiments.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
There is evidence that the "acid mantle" of the stratum corneum is important for both permeability barrier formation and cutaneous antimicrobial defense. The origin of the acidic pH of the stratum corneum remains conjectural, however. Both passive (e.g., eccrine/sebaceous secretions, proteolytic) and active (e.g., proton pumps) mechanisms have been proposed. We assessed here whether the free fatty acid pool, which is derived from phospholipase-mediated hydrolysis of phospholipids during cornification, contributes to stratum corneum acidification and function. Topical applications of two chemically unrelated secretory phospholipase sPLA2 inhibitors, bromphenacylbromide and 1-hexadecyl-3-trifluoroethylglycero-sn-2-phosphomethanol, for 3 d produced an increase in the pH of murine skin surface that was paralleled not only by a permeability barrier abnormality but also altered stratum corneum integrity (number of strippings required to break the barrier) and decreased stratum corneum cohesion (protein weight removed per stripping). Not only stratum corneum pH but also all of the functional abnormalities normalized when either palmitic, stearic, or linoleic acids were coapplied with the inhibitors. Moreover, exposure of intact murine stratum corneum to a neutral pH for as little as 3 h produced comparable abnormalities in stratum corneum integrity and cohesion, and further amplified the inhibitor-induced functional alterations. Furthermore, short-term applications of an acidic pH buffer to inhibitor-treated skin also reversed the abnormalities in stratum corneum integrity and cohesion, despite the ongoing decrease in free fatty acid levels. Finally, the secretory-phospholipase-inhibitor-induced alterations in integrity/cohesion were in accordance with premature dissolution of desmosomes, demonstrated both by electron microscopy and by reduced desmoglein 1 levels in the stratum corneum (shown by immunofluorescence staining and visualized by confocal microscopy). Together, these results demonstrate: (i) the importance of phospholipid-to-free-fatty-acid processing for normal stratum corneum acidification; and (ii) the potentially important role of this pathway not only for barrier homeostasis but also for the dual functions of stratum corneum integrity and cohesion.
Article
Although it is important that dermatologists and the general population know the irritation potential of products marketed for dry skin used for body cleansing, this information is not usually available. To assess the irritative effect of different soaps and liquid cleansers recommended for sensitive skin. To study the correlation of the irritation effect of each substance with its pH and with the presence or absence of syndet in the product. Seventeen products marketed for dry skin and 12 common soaps used by the general population were studied. Fresh soap emulsions (8%) were applied to the volar side of the right forearm of 30 individuals with sensitive skin for 5 consecutive days using aluminum chambers. The appearance of irritation (erythema, scaling and fissures) was recorded, scored, and expressed in an Irritation index (IrIn). The pH of each solution was measured. Products with a low IrIn were White Dove (Dove, Lever Pond's, Toronto, Ontario, Canada), Dove Baby, Cetaphil (bar) (Cetaphil, Gulderma Lab., Forth Worth, TX, USA), Dove liquid cleanser for hands, Dove pink, and Aderma (Adenma, Pierre Fabre, Dermo-Cosmetique, Boulagne, France). Most corresponded to syndet products. Among the most used brand-name soap, Camay Classic (Camay, Procter & Gamble de Mexico, México, U.F.) had the lowest IrIn. Dove Baby was the only product with a neutral pH. A significant correlation between pH and the IrIn of cleansers was found (P < 0.006). Most products recommended for sensitive skin have a considerable irritation effect, which is related to the pH of the product. Better regulation of advertisement specifications including the pH level and type of cleanser contained is necessary for the majority of soaps and cleansers.
Article
Skin-cleansing compositions based on alkyl carboxylates (soaps) have a higher irritation potential than those based on syndet surfactants such as alkyl isethionates or alkyl ether sulphates. Contributing factors include inherent differences in the irritation potential of soaps and syndet surfactants, pH-induced changes in surfactant solution chemistry, and the direct effects of pH on the physical properties of the stratum corneum (SC). Past work has not directly addressed the effect of solution pH on the SC itself and its potential role in cleanser-induced skin irritation. In the current work, alterations to SC properties induced by buffered pH solutions and two strongly ionizable surfactants, sodium dodecyl sulphate and sodium lauryl ether sulphate, at different pH values are measured. By utilizing optical coherence tomography (OCT) and infrared (IR) spectroscopy we have directly measured physical changes in SC proteins and lipids. Our results indicate that SC swelling, which reflects alterations to SC structural proteins, is increased significantly at pH 10, compared to pH 4 and 6.5. The transition temperature (T(m)) of SC lipids is found to increase at pH 10, compared to pH 4 and 6.5, suggesting a more rigid SC lipid matrix. Surfactants cause a further increase in swelling and lipid rigidity. Some aspects of what these results mean for SC physical properties as well as their implications to potential mechanisms of surfactant-induced skin irritation are discussed.
Subramanyan mechanical properties using linear skin rheometer. Part II: cumulative effect of cleansers and moisturizer
  • B Mok
  • P Bautista
  • K Kirnos
Mok W, Bautista B, Kirnos P, Subramanyan K. In vivo mechanical properties using linear skin rheometer. Part II: cumulative effect of cleansers and moisturizer. Unilever Research Internal Report, unpublished results, 2001.
Stratum corneum lipids and barrier function: biophysical studies of molecular organization in sphingomyelin and ceramide [NS] bilayers
  • D J Moore
Moore DJ. Stratum corneum lipids and barrier function: biophysical studies of molecular organization in sphingomyelin and ceramide [NS] bilayers. Recent Res Dev Lipids 2002: 6 : 55-63.
Unpublished results. Unilever Research and Development
  • Dj Moore
Moore DJ. Unpublished results. Unilever Research and Development, 2003.
Human in vivo methods for assessing the irritation potential of cleansing systems
  • F A Simion
Simion FA. Human in vivo methods for assessing the irritation potential of cleansing systems. In: Riger MM, Rhein LD, eds. Surfactants in Cosmetics. Surfactant Science Series, Vol. 68. New York, NY: Marcel Dekker, 1997: 519 -532.
On skin proteinsurfactant interactions. Paper presented at the Society of Cosmetic Chemists Meeting
  • A Lips
  • M Kp Ananthapadmanabhan
  • Vethamuthu
Lips A, Ananthapadmanabhan KP, Vethamuthu M, et al. On skin protein–surfactant interactions. Paper presented at the Society of Cosmetic Chemists Meeting, Washington, DC, May 8 –9, 2003.
Velez deposition of cholesterol and triglycerides from dual chamber body wash. Unpublished results. Unilever Research and Development
  • J Naser
  • Atlas
  • Chang
  • Meyers
  • S Morgan
Naser M, Atlas J, Chang E, Meyers L, Morgan L, Velez S. In vivo deposition of cholesterol and triglycerides from dual chamber body wash. Unpublished results. Unilever Research and Development, 1998.
Deposition of lipids from personal wash cleansers
  • J Subramanyan
  • Wong
  • A Kp Ananthapadmanabhan
  • Pereira
Subramanyan K, Wong J, Ananthapadmanabhan KP, Pereira A. Deposition of lipids from personal wash cleansers. Paper presented at the 21st IFSCC Conference, Berlin, Germany, September 11-14, 2000.
Dermatological observations
  • W Matthies
Matthies W. Dermatological observations. In: Gloxhuber C, Kunstler K, eds. Anionic Surfactants, Surfactant Science Series, Vol. 43. New York, NY: Marcel Dekker, 1992: 291-329.
Unilever Research and Development
  • D J Moore
Moore DJ. Unpublished results. Unilever Research and Development, 2003.