Artificial Sebum Research Articles

Bioinspired skin-like in vitro model for investigating catheter-related bloodstream infections

Intravenous (IV) catheter-related bloodstream infections (CRBSIs) cause significant risks in healthcare, necessitating advancements in catheter design and materials. This study investigates the effectiveness of Ecoflex, a silicone-based material, in studying CRBSIs through the development of skin-like replicas that mimic human skin properties for use in wearable sensing devices. We characterized the replica’s bioinspired surface roughness, wettability, bacterial adhesion, and mechanical properties and validated its performance using in vitro IV simulation. The results demonstrated that the bioinspired model replicates human skin textures with less than 7.5% error for surface roughness ranging from 0.05 μm to 6.3 μm. Wettability tests revealed that the artificial sebum application significantly reduced the static contact angles for deionized water and artificial sweat. Comprehensive mechanical testing revealed material high elasticity and resilience, suitable for dynamic biomedical applications. Bacterial adhesion studies using Staphylococcus epidermidis showed varying adhesion patterns influenced by surface roughness, highlighting the potential for material texture to impact infection risk. In IV therapy simulations, we observed bacterial growth dynamics over the incubation period. Our findings suggest that Ecoflex-based skin-like replicas can serve as a valuable tool for developing and testing new catheters, while the potential for use in other medical innovation devices, including wearable sensing devices, ultimately contributes to improved patient outcomes and infection control strategies.

Development of Bacillus stratosphericus Lysate Concentrate to Control Sebum Secretion through In vitro Studies and Clinical Trial

The sebum on human skin is generated for various causes. The composition of the formed sebum increases the proliferation of Cutibacterium acnes (C. acnes) residing on the skin. As C. acnes proliferates, it produces skin irritants that stimulate the sebaceous glands, increasing sebum production. Skin troubles such as acne may occur. The lysate concentrates of Bacillus stratosphericus (B. stratosphericus), first discovered in the stratosphere, confirmed a 66.35% inhibition of Nitric Oxide (NO) production at 0.50 mg/ml concentration in vitro. Additionally, the growth inhibition efficacy of B. stratosphericus lysate concentrate (BSLC) against C. acnes was confirmed, showing a 95.1% inhibition of growth proliferation at a consistency of 0.50 mg/ml. Based on the in vitro results, the efficacy of BSLC in degrading and reducing sebum was confirmed by reacting it with artificial sebum to various concentrations. The results showed a concentration-dependent decrease in artificial sebum ccording to the efficacy results confirmed in vitro, a clinical trial was conducted to evaluate the daily sebum reduction efficacy of a serum formulation containing 50 mg/ml of BSLC. After a 4-week application, the test group containing BSLC determined a significant 28.68% reduction in sebum levels, demonstrating the practical implications of the research. In conclusion, BSLC is considered to have sufficient industrial value as a valuable ingredient for the cosmetics industry aimed at sebum improvement.

A review of artificial sebum formulations, their compositions, uses and physicochemical characteristics.

Sebum is a complex mixture of skin lipids responsible for lubrication, moisture retention and skin protection from external factors such as bacteria and fungi. The physicochemical properties of natural sebum are not well understood and are not easily accessible. Artificial sebum is widely used for sebum-related research such as dermal bioaccessibility, fingerprint production, dermatology, removal and sebum studies. It was found that the composition of artificial sebum affects the bioaccessibility of metals and drugs as well as the growth of some strains of bacteria. Squalene present in sebum was also found to be responsible for creating yellow stains on fabrics, whereas an increased concentration of fatty acids and triglycerides can lead to higher malodour of fabrics. Moreover, sebum and artificial sebum are poorly characterized with only 20 of 81 formulations characterized by certain techniques such as differential scanning calorimetry, nuclear magnetic resonance and thin-layer chromatography. This article reviews the artificial sebum formulations reported in the open literature between 1965 and 2023. We have discussed the compositions, uses and characterization techniques of artificial sebum used in the previous work and compared their properties to those of human sebum. A total of 81 artificial sebum formulations were found across the literature with 17 new formulations identified. The artificial sebum composition varies greatly between publications and there is no consistent formulation. There is a wide range of chemicals that are used as the main components of artificial sebum. We have highlighted the effect of chemical composition and individual compounds on the overall properties of the artificial sebum reported, and recommend that there is a great potential for creating personalized cosmetics and home care products once the characteristics of sebum are better understood.

Intradermal injection of Cutibacterium acnes and staphylococcus: A pustular acne-like murine model.

Skin 16S microbiome diversity analysis indicates that the Staphylococcus genus, especially Staphylococcus aureus (S. aureus), plays a crucial role in the inflammatory lesions of acne. However, current animal models for acne do not fully replicate human diseases, especially pustular acne, which limits the development of anti-acne medications. The aim is to develop a mouse model for acne, establishing an animal model that more closely mimics the clinical presentation of pustular acne. This will provide a new research platform for screening anti-acne drugs and evaluating the efficacy of clinical anti-acne experimental treatments. Building upon the existing combination of acne-associated Cutibacterium acnes (C. acnes) with artificial sebum, we will inject a mixture of S. aureus and C. acnes locally into the dermis in a 3:7 ratio. We found that the acne animal model with mixed bacterial infection better replicates the dynamic evolution process of human pustular acne. Compared to the infection with C. acnes alone, mixed bacterial infection resulted in pustules with a distinct yellowish appearance, resembling pustular acne morphology. The lesions exhibited redness, vascular dilation, and noticeable congestion, along with evident infiltration of inflammatory cells. This induced higher levels of inflammation, as indicated by a significant increase in the secretion of inflammatory factors such as IL-1β and TNF-α. This model can reflect the clinical symptoms and development of human pustular acne, overcoming the limitations of animal models commonly used in basic research to study this situation. It provides support for foundational research and the development of new acne medications.

A novel fullerene composite material for directional oil control and antioxidant.

There are very few cosmetic ingredients that can target oil control and extend the wear time. Fullerenes have been reported to have excellent antioxidant capacity and a variety of biological activities, such as quenching free radicals, inhibiting lipid peroxidation, and promoting lipid flocculation. The purpose of applying foundation makeup on the face is to make the skin color even, but the secretion and oxidation of skin oil will make the makeup mottled and dull. In order to solve this problem, a fullerene composite material that can directionally absorb oil and resist oil oxidation has been developed. Fullerenes and hydroxyapatite composite was prepared by high pressure homogenization under alkaline condition. The indicated morphology and structure were characterized by SEM, UV-Vis, Raman, and XRD. The oil absorption capacity was determined by adding the C60-hydroxyapatite composite to a mixed solution of hexane and oil, shaking for 1 h, filtering, analyzed by GC-MS, and calculating the oil absorption by external standard method. Artificial sebum was prepared by adding different mass of water and oleic acid to screen the optimum ratio. C60-hydroxyapatite mixture and C60-hydroxyapatite composite were added to the artificial sebum to test the oil-absorbing capacity of the materials. The hydroxyl radical scavenging ability of C60-hydroxyapatite composite containing different fullerene contents was measured by X-band ESR spectroscopy, and the long-term radical scavenging ability of the composites was tested in comparison with VC. Antioxidant experiment is adding C60-hydroxyapatite composite material, and hydroxyapatite to oleic acid, then the UV light irradiation is aimed to accelerate the oxidation of oleic acid. Oleic acid act as a control group, and make the detection of oleic acid peroxide value after 7 days. The safety of the materials was tested by using culture media to soak the C60-hydroxyapatite composite for 24 h and then used to culture cells. The characterization of SEM, UV-Vis, Raman, and XRD showed that fullerene clusters were dispersed on the surface of hydroxyapatite stably, and they formed a stable composite. The adsorption rates of C60-hydroxyapatite composites for oleic acid, phenyl trimethicone, caprylic capric glyceride, isooctyl palmitate, mineral oil, olive oil, and dimethicone were 60.5%, 9.3%, 9.15%, 5.24%, 2.94%, 1.01%, and 0%, respectively. The flocculation amount of artificial sebum was 5.9 g per gram of C60-hydroxyapatite mixture and 24.2 g per gram of C60-hydroxyapatite composite. C60-hydroxyapatite composites have excellent quenching ability for hydroxyl radicals. When the fullerene content is 1, 2, 3, and 4 mg/kg, the quenching rates are 25.02%, 39.57%, 49.75%, and 62.24%, respectively. The quenching effect was enhanced with the increase of fullerene content, and it had strong long-term antioxidant properties. It can also be proved that C60-hydroxyapatite composites have strong antioxidant capacity through antioxidant experiments. The peroxide value of oleic acid on Day 0 was 2.8, and after 7 days of UV irradiation, the peroxide values of blank control, hydroxyapatite group, C60-hydroxyapatite composite containing 0.5% and 1% fullerenes four groups of materials were 8.02 meq O2/kg, 7.98 meq O2/kg, 7.11 meq O2/kg, and 6.87 meq O2/kg, respectively. The cell activity was 20.94% and 99.2% after the cells were cultured for 24 h using C60-hydroxyapatite composite and hydroxyapatite extracts, respectively, and the addition of fullerene was able to significantly increase the cell activity. Fullerene hydroxyapatite complex has excellent directional oil absorption characteristics, which can effectively remove free radicals and reduce skin oil oxidation.

Investigating the impact of sebum secretion on liquid makeup foundation darkening and its solution.

Darkening has been an issue of concern for foundation products. The secretion of sebum plays a significant role in the process of foundation darkening, but the underlying mechanisms and solutions have been rarely reported. The aim of this study was to explore the relationship between sebum secretion and liquid foundation darkening and to provide possible solutions for reducing sebum-induced darkening in liquid foundation. Artificial sebum in different concentrations was added to a basic liquid foundation to simulate different stages of sebum secretion. The colour of the mixture was then measured by a spectrophotometer on the standard opacity chart. Potential technical solutions for anti-darkening were applied to a basic liquid foundation, and its ability to anti-darkening was further verified invivo. (1) The influences of sebum addition on liquid foundation darkening had a significant positive correlation with the increase in transmissivities (R2 = 0.852, p < 0.01). (2) A certain range of sebum addition can reduce the darkening of volatile foundations. (3) The liquid foundations using pigments with high dispersibility in sebum were less influenced by sebum. (4) The replacement of pigments with oil-fixing ability could effectively reduce the darkening of liquid foundations induced by sebum (p < 0.01). The effect of sebum on the darkening of liquid foundation was accompanied by a greater transmissivity as its pigment concentration decreased. Balanced volatility, the addition of powders with higher sebum dispersibility and the replacement of oil-fixing powders could reduce the darkening of the liquid foundation caused by sebum secretion.

Formulation of Botanical Shampoo Infused with Standardised Mangosteen Peel Extract for Healthy Hair and Scalp

In recent decades, there has been a growing demand for shampoos derived from botanical sources due to their avoidance of synthetic and highly allergenic chemicals used as bioactives and excipients. These hair care products are free from sulfates, parabens, silicones, synthetic fragrances, and artificial colours. Natural shampoos are sustainable, skin-friendly, and eco-friendly to the environment. Garcinia mangostana (Mangosteen) peel is usually discarded as agricultural waste. It consists of numerous bioactives which exhibit promising activities for hair care and scalp maintenance. This study aimed to formulate and evaluate a novel hair shampoo containing standardised mangosteen peel extract. The formulation of the mangosteen shampoo utilised botanical ingredients and naturally derived components. It underwent an evaluation to assess its physicochemical properties, including visual inspection, pH, surface tension, percentage solid content, wetting time, foam ability and stability, as well as dirt dispersion. These properties were then compared to those of two commercially available hair shampoos. Its antimicrobial activity towards Malassezia furfur ATCC 14521 and Staphylococcus aureus ATCC 25923 was also examined and compared with the commercial shampoo using the microbroth dilution method. Its antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity assay. It was noticed that all formulations (F1–F4) had acceptable physicochemical properties, and they fell within the standard range. F2 had the best antifungal activity (MIC 0.039 mg/mL, MFC 0.156 mg/mL), and moderate antibacterial (MIC 2.50 mg/mL, MBC 5.00 mg/mL) and antioxidant activities (IC50 21.9 ± 3.27 mg/mL; AEAC 26.3 ± 4.06 mg AA/100 g sample). A microscopic examination of hair strands after washing revealed the successful removal of artificial sebum, signifying a good detergency effect. The physical and chemical properties of the hair shampoo formula remained stable without phase separation. In conclusion, the formulated clean hair shampoo with standardised mangosteen peel extract has good cleansing properties, and it is effective in inhibiting dandruff-causing microbial and scavenging free radicals.

Estimated Dermal Penetration of Tetrachlorvinphos (TCVP) in Humans Based on In Silico Modeling and In Vitro and In Vivo Data

ABSTRACT Tetrachlorvinphos (TCVP) is the pesticidal active ingredient in some collars for dogs and cats. The objective of this study was to provide a refined estimate of dermal penetration of TCVP in humans using in silico predictions as well as in vitro and in vivo data. The in vivo dermal absorption of TCVP was previously studied in the rat and shown to be saturable, ranging from 21.7% (10 µg/cm2) down to 3% (1000 µg/cm2) Subsequent in silico predictions were conducted for rats and humans to provide initial evaluations of species and dose-dependent differences in dermal absorption. A definitive comparison of TCVP systemic exposure in rat and human following dermal application was then conducted via a standard in vitro assay. TCVP dose levels of 10, 100, or 1000 μg/cm2 were applied to excised rat and human skin mounted in flow-through diffusion cells. The vehicle was 1% hydroxypropylmethylcellulose (HPMC) in water. An additional 5 μg/cm2 dose was applied to excised human skin only. The in vitro dermal absorption of TCVP was also assessed from artificial sebum at dose levels of 5, 10, or 100 μg/cm2 applied to human skin only. Utilizing the so-called triple pack approach with in vitro and in vivo rat data and in vitro human data, dermal absorption for TCVP was calculated for humans. In silico modeling indicated absorption of TCVP through human skin might be 3- to 4- fold lower than rat skin at all application levels, with a maximum dermal absorption of 9.6% at the lowest exposure of 10 µg/cm2, down to 0.1% at 1000 µg/cm2. Similar species differences were also found in the definitive in vitro absorption assays. Modeling overestimated TCVP human dermal absorption (9.6%) as compared to excised human skin results (1.7%) for the HPMC vehicle at the lowest exposure (10 µg/cm2), with better agreement at the higher exposures. Conversely, modeling accurately predicted rat dermal absorption (27.9%) as compared to in vivo rat results (21.7%) at the lowest exposure in HPMC, with diminished agreement at the higher exposures. As a first approximation, in silico estimates of dermal absorption are useful; however, these tend to be more variable than in vitro or in vivo measurements. TCVP dermal penetration measured in vitro was lower in 1% HPMC vehicle as compared to artificial sebum. For the 1% HPMC vehicle, in vitro rat dermal absorption was similar to data obtained for in vivo rats, giving confidence in the triple pack approach. In consideration of the triple pack approach, estimated human dermal absorption from 1% HPMC was ≤2%. Based upon excised human skin determinations directly, estimated human dermal absorption of TCVP from artificial sebum was ≤7%.

Enhanced migration of plasticizers from polyvinyl chloride consumer products through artificial sebum

In the present study, the migration of plasticizers from modeled and commercial polyvinyl chloride (mPVC and cPVC, respectively) to poly(dimethylsiloxane) via artificial sebum was assessed to mimic the dermal migration of plasticizers. In addition, the various factors affecting migration of phthalic acid esters (PAEs) from diverse PVC products were investigated. The migrated mass and migration ratio of PAEs increased but the migration rate decreased over time. The migration rate increased with sebum mass, contact time, and temperature but decreased under higher pressure. Low-molecular-weight PAEs (dimethyl phthalate and diethyl phthalate) migrated in higher amounts than high-molecular-weight PAEs (dicyclohexyl phthalate [DCHP] and diisononyl phthalate [DINP]). Diffusion of all PAEs in mPVC increased with temperature, with diffusion coefficients ranging from 10−13 to 10−15, 10−12 to 10−14, and 10−10 to 10−12 cm2·s−1 at 25 °C, 40 °C, and 60 °C, respectively; the enthalpy of activation ranged between 127 and 194 kJ·mol−1. Moreover, migration depended on total PAE content of the product, as the diffusion coefficient for DINP in cPVC (softer PVC) was approximately three orders of magnitude higher than that for DINP in mPVC (harder PVC); this may be due to the increase in free volume with increasing plasticizer content. Finally, the daily exposure doses of the plasticizers were estimated. These findings will be helpful for estimating dermal exposure risk.

Effect of Hydrogel Substrate Components on the Stability of Tetracycline Hydrochloride and Swelling Activity against Model Skin Sebum.

Due to its high instability and rapid degradation under adverse conditions, tetracycline hydrochloride (TC) can cause difficulties in the development of an effective but stable formulation for the topical treatment of acne. The aim of the following work was to propose a hydrogel formulation that would ensure the stability of the antibiotic contained in it. Additionally, an important property of the prepared formulations was the activity of the alcoholamines contained in them against the components of the model sebum. This feature may help effectively cleanse the hair follicles in the accumulated sebum layer. A series of formulations with varying proportions of anionic polymer and alcoholamine and containing different polymers have been developed. The stability of tetracycline hydrochloride contained in the hydrogels was evaluated for 28 days by HPLC analysis. Formulations containing a large excess of TRIS alcoholamine led to the rapid degradation of TC from an initial concentration of about 10 µg/mL to about 1 µg/mL after 28 days. At the same time, these formulations showed the highest activity against artificial sebum components. Thanks to appropriately selected proportions of the components, it was possible to develop a formulation that assured the stability of tetracycline for ca. one month, while maintaining formulation activity against the components of model sebum.

Sebum‐Membrane‐Inspired Protein‐Based Bioprotonic Hydrogel for Artificial Skin and Human‐Machine Merging Interface

AbstractAs an on‐skin electronic device, artificial skin shows great potential in medical monitoring and personal electronics, which also holds promise to develop human‐machine merging interfaces. However, merging artificial skins with human bodies is largely restricted by the dissimilarity of material compositions in existing artificial skins and biological tissues. Naturally conductive protein is a potential material candidate for artificial skins, nevertheless, it suffers from the critical issue of dehydration which harms its proton conductivity. Inspired by the sebum membrane of human skin, herein, a protein‐based bioprotonic hydrogel (PBH) with reliable water retention ability is reported for artificial skins. The bovine serum albumin with natural proton conductivity is utilized in the PBH, and the glycerol that originally presents on human skin surface is used as an artificial sebum membrane to retain water. The PBH can act as a bioprotonic skin (B‐skin) for collecting electrophysiological signals and self‐powered sensing. Based on the B‐skin, intelligent robot and cellphone control systems are demonstrated. Compared with present artificial skins, this B‐skin is all made out of biological materials that are consistent with material components of human skin tissues including proteins, endogenous glycerol, and water. Such a B‐skin may enable the development of next‐generation human‐machine merging interfaces.

Sweat and Sebum Preferences of the Human Skin Microbiota.

The microorganisms inhabiting human skin must overcome numerous challenges that typically impede microbial growth, including low pH, osmotic pressure, and low nutrient availability. Yet the skin microbiota thrive on the skin and have adapted to these stressful conditions. The limited nutrients available for microbial use in this unique niche include those from host-derived sweat, sebum, and corneocytes. Here, we have developed physiologically relevant, synthetic skin-like growth media composed of compounds present in sweat and sebum. We find that skin-associated bacterial species exhibit unique growth profiles at different concentrations of artificial sweat and sebum. Most strains evaluated demonstrate a preference for high sweat concentrations, while the sebum preference is highly variable, suggesting that the capacity for sebum utilization may be a driver of the skin microbial community structure. In particular, the prominent skin commensal Staphylococcus epidermidis exhibits the strongest preference for sweat while growing equally well across sebum concentrations. Conversely, the growth of Corynebacterium kefirresidentii, another dominant skin microbiome member, is dependent on increasing concentrations of both sweat and sebum but only when sebum is available, suggesting a lipid requirement of this species. Furthermore, we observe that strains with similar growth profiles in the artificial media cluster by phylum, suggesting that phylogeny is a key factor in sweat and sebum use. Importantly, these findings provide an experimental rationale for why different skin microenvironments harbor distinct microbiome communities. In all, our study further emphasizes the importance of studying microorganisms in an ecologically relevant context, which is critical for our understanding of their physiology, ecology, and function on the skin. IMPORTANCE The human skin microbiome is adapted to survive and thrive in the harsh environment of the skin, which is low in nutrient availability. To study skin microorganisms in a system that mimics the natural skin environment, we developed and tested a physiologically relevant, synthetic skin-like growth medium that is composed of compounds found in the human skin secretions sweat and sebum. We find that most skin-associated bacterial species tested prefer high concentrations of artificial sweat but that artificial sebum concentration preference varies from species to species, suggesting that sebum utilization may be an important contributor to skin microbiome composition. This study demonstrates the utility of a skin-like growth medium, which can be applied to diverse microbiological systems, and underscores the importance of studying microorganisms in an ecologically relevant context.

Assessing the effect of cleansing products on artificially polluted human hairs and skin through in vivo and in vitro models.

Based on in vivo data, in vitro models and new methods are created to mimic the impact of aerial pollution onto the hair surface and assess the efficacy of different formulae prototypes. Two protocols are developed to mimic the pollution effect, in vitro, on purchased swatches, and in vivo, on scalps and forearms. First, with an artificial sebum mixed with Carbon Black particles, named "sebollution," we evaluated, through an instrumental color measurement, the cleansing efficacy of some shampoo on scalp and hair. The second protocol allowed to assess the interaction between hair care product deposit (shampoo, conditioner, mask, and leave-on) on hair and carbon black particles spread on fiber. The quantification of particle coverage allowed to evaluate the efficiency of a formula to limit the aerial pollution deposit on hair fiber. To simplify and accelerate the evaluation of 42 shampoo formulae, an extrapolation of the scalp cleaning process was validated on forearm. The respective cleanabilities were calculated and covered a large range of efficacy, from 5%, for a basic bland shampoo generally used to reset swatches, to a strong deep cleansing efficacy of 100%. On hair swatches, cleanability efficiencies of five shampoo were also evaluated to eliminate the deposited of sebollution, in a range of 40%-80%. To quantify the efficacy of preventing the deposition of carbon particle on hair surface, the percentage of coverage of 45 different products was measured, from 2% to 16%. The performance depended of the product category (shampoo, conditioner, mask, and leave-on), driven by the performance of the product deposit, and the capacity of this deposit to interact with aerial pollution. Three new protocols and evaluation methods are proposed to evaluate and quantify the performance of hair care product, to remove/clean, limit, and protect the hair fibers against the aerial pollution that could interact with hair, scalp and sebum. The validation of these approaches was done through the testing of a large panel of hair care product leading to a complete and sincere evaluation of cleansing and anti-deposit efficacy. Combining the knowledge acquired on pollution impact on hair and the development of specific way of evaluation, this work reinforced the rationale of using and developing new cosmetic products that reduced the impact of pollution upon some hair properties.

Development of skin sebum medium and inhibition of lipase activity in Cutibacterium acnes by oleic acid.

Cutibacterium acnes is associated with the exacerbated inflammation of acne vulgaris, which occurs through the immune induction and pathogenicity factor production. Sebum, which is not present in the growth medium currently used to study acne, is present in acne pustules in differing concentrations among the pathological stages, such as the initial formation and inflammatory phase. To evaluate the effect of C. acnes on inflammation exacerbation in acne pustules in vitro, we developed an skin sebum medium containing artificial sebum and studied the growth and pathogenicity factor production of C. acnes in the skin sebum medium. The growth and lipase activity of C. acnes ATCC11828 were tested using skin sebum medium containing different sebum concentrations. Only lipase activity decreased in the skin sebum medium culture containing 0.5 % sebum when compared with that without sebum, while both growth and lipase activity decreased in cultures with 1.0 % sebum. Therefore, the growth and lipase activity of C. acnes changed in the presence of sebum. Furthermore, when the growth and lipase activity of C. acnes were tested in skin sebum medium containing sebum components, unsaturated fatty acids, such as oleic acid and triolein, led to a decrease in lipase activity without inducing a change in growth. In the presence of oleic acid, C. acnes lipase activity decreased noncompetitively in a concentration-dependent manner. Our data showed that C. acnes growth and lipase activity changed upon sebum addition to the skin sebum medium, and acne inflammation caused by C. acnes needs to be studied under conditions similar to those in acne pustules.

Effects of time, temperature, and sebum layer on migration rate of plasticizers in polyvinyl chloride products

Large amounts of plasticizers, such as di(2-ethylhexyl) phthalate (DEHP) and dioctyl terephthalate (DOTP), are added to various polyvinyl chloride (PVC) products. To assess the human exposure to these plasticizers on using PVC products, it is important to know their migration rate. However, conventional migration tests conducted at a fixed time and temperature are often insufficient for determining possible variations in migration rates with respect to time, temperature, and sebum layer. In this study, the migration rates of DEHP and DOTP from five PVC products were measured using a polydimethylsiloxane (PDMS) sampler at different times and temperatures, in the presence and absence of artificial sebum. Although the migrated mass of the plasticizers increased over time, the average migration rate decreased. The average migration rates increased with increasing temperature and in the presence of an artificial sebum layer between the product and the PDMS sampler. When the artificial sebum layer was added, the average migration rate increased considerably by a factor of 1.5–14, suggesting that sebum should be considered to avoid the underestimation of dermal exposure to highly hydrophobic plasticizers, such as DEHP and DOTP. Based on the measured values, a conceptual analysis was conducted to quantitatively assess the difference in the migration rate of plasticizers caused by the difference between the time set for the migration test and the exposure time when the product is used. To reduce uncertainties and the potential underestimation of dermal exposure, an appropriate time for the experiment should be set to simulate the exposure scenario of a given product.

Development of Artificial-Sebum-Containing Leeming and Notman Agar Medium to Enhance the Growth of Malassezia.

Modified Leeming and Notman agar medium (mLNA) has been widely utilized to grow lipophilic fungi belonging to the genus Malassezia. We developed a new artificial-sebum-containing mLNA to obtain higher yields of Malassezia species. The olive oil in mLNA was replaced with an artificial sebum composed of triglyceride (triolein), diglyceride (glyceryl distearate), fatty acids (palmitic acid, myristic acid, pentadecanoic acid, and oleic acid), and squalene. Furthermore, the Tween 60 was replaced with self-emulsifying glyceryl stearate. Nine human-associated Malassezia species grew well on the artificial-sebum-containing mLNA, and the most predominant fungus on human skin, Malassezia restricta, exhibited double wet cell weight in artificial sebum-containing mLNA compared to wet cell weight in standard mLNA.

Development of a printed quality control test strip for the analysis and imaging of fingermark composition

In the last decade, there have been many scientific developments regarding the use of mass spectrometry to analyse the composition of fingermarks. In this context, the development of a dedicated quality control test strip would benefit the forensic community by providing a way to assess the reproducibility of the measures as well as to perform inter-laboratory comparisons. To accomplish this goal, the use of a chemical printer offers the possibility of combining a visual template with artificial fingerprint secretions. The design of the quality control test strip as well as the preliminary assessment of its performance with fingermark detection reagents and matrix-assisted laser desorption-ionisation combined with mass spectrometry imaging (MALDI-MSI) are presented in this paper. The chosen template combines two geometric patterns intended to help assess the chemical analysis (full square) and imaging (lined square) capabilities of the instrument. The artificial secretion is composed of two distinct solutions: artificial sweat and artificial sebum. The printing reproducibility and chemical homogeneity of the quality control test strips were assessed in two ways: (1) using MALDI-MSI, the printed pattern was analysed and the m/z values compared to the reference list based on the artificial secretion composition, and (2) using two common fingermark detection techniques, the printed pattern was processed using an amino acid reagent (ninhydrin) and a lipid stain (Oil Red O). Overall, the results highlight the potential of a printed quality control test strip for the assessment of the quality of fingermark detection techniques as well as the possibility of performing quality monitoring of mass-spectrometry-based techniques over time.

Particle transfer and adherence to human skin compared with cotton glove and pre-moistened polyvinyl alcohol exposure sampling substrates

Measurement of skin exposure to particles using interception (e.g., cotton gloves) and removal (e.g., wiping) sampling techniques could be inaccurate because these substrates do not have the same topography and adhesion characteristics as skin. The objective of this study was to compare particle transfer and adherence to cotton gloves, cotton gloves with artificial sebum, and a pre-moistened polyvinyl alcohol (PVA) material with bare human skin (fingertip, palm). Experiments were performed with aluminum oxide powder under standardized conditions for three types of surfaces touched, applied loads, contact times, and powder mass levels. In the final mixed model, the fixed effects of substrate, surface type, applied load, and powder mass and their significant two-way interaction terms explained 71% (transfer) and 74% (adherence) of the observed total variance in measurements. For particle mass transfer, compared with bare skin, bias was −77% (cotton glove with sebum) to +197% (PVA material) and for adherence bias ranged from −40% (cotton glove) to +428% (PVA material), which indicated under- and over-sampling by these substrates, respectively. Dermal exposure assessment would benefit from sampling substrates that better reflect human skin characteristics and more accurately estimate exposures. Mischaracterization of dermal exposure has important implications for exposure and risk assessment.

Copper Chelants and Antioxidants in Laundry Detergent Formulations Reduce Formation of Malodor Molecules on Fabrics

AbstractFor consumers who use laundry detergents, a top unmet need is to reduce malodor that can persist on fabrics, even after washing and drying. A known source of odor is autoxidation of residual sebum on fabric, leading to the generation of an array of odiferous compounds. To prevent this oxidation process, two technologies were evaluated: (i) antioxidants to scavenge radicals and (ii) metal chelants to inhibit the involvement of copper ions as catalysts in the autoxidation process. Copper is a common component of sweat, soil, and municipal water supplies, especially where copper piping is involved, which is typical in many US homes and businesses. For the evaluations, swatches of fabric were treated with artificial sebum, then washed in commercial washing machines with tap water containing laundry detergent, and dried using commercial dryers. Copper added to the wash at a level representative of consumer homes substantially increased the formation of known malodor molecules. Copper chelants [in particular, diethylenetriamine (DETA)] added to the wash were effective in inhibiting the formation of malodor molecules. In combination with antioxidants [in particular, methyl 3‐(3, 5‐di‐tert‐butyl‐4‐hydroxyphenyl)propanoate (MtBHPP)], the inhibitory effect was greater. Even at low concentrations (&lt;1%), DETA and MtBHPP were effective at inhibiting the generation of known malodor molecules on fabrics. As DETA and MtBHPP meet performance, cost, and stability considerations, they hold promise for use in high‐quality commercial laundry detergent products designed to eliminate malodor on consumer fabrics.

Human in vitro percutaneous absorption of bisphenol S and bisphenol A: A comparative study

Bisphenol A (BPA) is widely used in industrial products. Due to the toxicity of this compound, and to comply with restrictions and regulations, manufacturers have progressively replaced it by substitutes. One of the main substitutes used is bisphenol S (BPS). Despite increasing use in many products, the effects of BPS on human health have been little investigated, and studies on percutaneous BPS absorption and particularly toxicokinetic data are lacking. However, the endocrine-disrupting activity of BPA and BPS appears comparable. Dermal contact is a significant source of occupational exposure and is the main route during handling of bisphenol-containing receipts by cashiers. Here, percutaneous BPS absorption was investigated and compared to that of BPA. Experiments were performed according to OECD guidelines. Test compounds dissolved in a vehicle - acetone, artificial sebum or water – were applied in vitro to fresh human skin samples in static Franz diffusion cells. Flux, cumulative absorbed dose and distribution of dose recovered were measured. BPA absorption was vehicle-dependent ranging from 3% with sebum to 41% with water. BPS absorption was much lower than BPA absorption whatever the vehicle tested (less than 1% of applied dose). However, depending on the vehicle 20% to 47% of the applied BPS dose remained in the skin, and was consequently potentially absorbable. Both BPA and BPS were mainly absorbed without biotransformation. Taken together, these results indicate that workers may be exposed to BPS through skin when handling products containing it. This exposure is of concern as its toxicity is currently incompletely understood.