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.

Le sébum est un mélange complexe de lipides cutanés responsable de la lubrification, de la rétention d'humidité et de la protection de la peau contre des facteurs externes tels que les bactéries et les champignons. Les propriétés physico­chimiques du sébum naturel ne sont pas bien comprises et ne sont pas facilement disponibles. Le sébum artificiel est largement utilisé pour la recherche liée au sébum, comme la bioaccessibilité cutanée, la production d'empreintes digitales, la dermatologie, le retrait et les études sur le sébum. Il a été constaté que la composition du sébum artificiel affecte la bioaccessibilité des métaux et des médicaments ainsi que la croissance de certaines souches de bactéries. Le squalène présent dans le sébum s'est également avéré responsable de la formation de taches jaunes sur les tissus, tandis qu'une concentration accrue d'acides gras et de triglycérides peut entraîner une odeur désagréable plus élevée des tissus. En outre, le sébum et le sébum artificiel sont mal caractérisés avec seulement 20 formulations sur 81 caractérisées par certaines techniques telles que la calorimétrie à balayage différentiel, la résonance magnétique nucléaire et la chromatographie sur couche mince. Cet article examine les formulations de sébum artificiel rapportées dans la littérature ouverte entre 1965 et 2023. Nous avons discuté des compositions, des utilisations et des techniques de caractérisation du sébum artificiel utilisé dans l'ouvrage précédent et comparé leurs propriétés à celles du sébum humain. Au total, 81 formulations de sébum artificiel ont été trouvées dans la littérature, avec 17 nouvelles formulations identifiées. La composition du sébum artificiel varie considérablement d'une publication à l'autre et il n'existe pas de formulation cohérente. Il existe un large éventail de produits chimiques qui sont utilisés comme principaux composants du sébum artificiel. Nous avons souligné l'effet de la composition chimique et des composés individuels sur les propriétés globales du sébum artificiel rapporté, et nous soutenons qu'il existe un grand potentiel pour la création de produits cosmétiques et de soins à domicile personnalisés une fois que les caractéristiques du sébum seront mieux comprises.

Analyzing the Accuracy of Critical Micelle Concentration Predictions Using Deep Learning.

This paper presents a novel approach to predicting critical micelle concentrations (CMCs) by using graph neural networks (GNNs) augmented with Gaussian processes (GPs). The proposed model uses learned latent space representations of molecules to predict CMCs and estimate uncertainties. The performance of the model on a data set containing nonionic, cationic, anionic, and zwitterionic molecules is compared against a linear model that works with extended connectivity fingerprints (ECFPs). The GNN-based model performs slightly better than the linear ECFP model when there is enough well-balanced training data and achieves predictive accuracy that is comparable to published models that were evaluated on a smaller range of surfactant chemistries. We illustrate the applicability domain of our model using a molecular cartogram to visualize the latent space, which helps to identify molecules for which predictions are likely to be erroneous. In addition to accurately predicting CMCs for some surfactant classes, the proposed approach can provide valuable insights into the molecular properties that influence CMCs.

Surface-Grafted Poly(ionic liquid) that Lubricates in Both Non-polar and Polar Solvents.

We show that a surface-grafted polymer brush, 1-n-butyl-3-vinyl imidazolium bromide-based poly(ionic liquids), is able to reduce the interfacial friction by up to 66% and 42% in dodecane and water, respectively. AFM-based force spectroscopy reveals that the polymer brush adopts distinctively different interfacial conformations: swollen in water but collapsed in dodecane. Minimal surface adhesion was observed with both polymer conformations, which can be attributed to steric repulsion as the result of a swollen conformation in water or surface solvation when the hydrophobic fraction of the polymer was exposed to the dodecane. The work brings additional insight on the polymer lubrication mechanism, which expands the possible design of the polymer architecture for interfacial lubrication and modification.