Silica aerogels have drawn a lot of interest both in science and technology because of their low bulk density (up to 95% of their volume is air), hydrophobicity, low thermal conductivity, high surface area, and optical transparency. Aerogels are synthesized from molecular precursors by sol-gel processing. Special drying techniques must be applied to replace the pore liquid with air while maintaining the solid network. Supercritical drying is most common; however, recently developed methods allow removal of the liquid at atmospheric pressure after chemical modification of the inner surface of the gels, leaving only a porous silica network filled with air. Therefore, by considering the surprising properties of aerogels, the present review addresses synthesis of silica aerogels by the sol-gel method, as well as drying techniques and applications in current industrial development and scientific research.

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Androgens affect several human skin and prostate functions, and the androgen receptor is crucial for regulating the androgen-related mechanisms. In this study, we assessed the antagonizing effects of a Scutellaria baicalensis extract and its main component baicalin on proliferation of human scalp dermal papilla cells. First, the extract and baicalin slightly dissociated the radioisotope-labeled androgen receptor-agonist complex in the androgen receptor binding assay, and the IC50 values were measured to assess the androgen receptor antagonistic effect of the extract (93 µg/mL) and baicalin (54.1 µM). Second, the extract and baicalin treatments dose-dependently inhibited the overgrowth of LNCaP prostate cancer cells, which were stimulated by dihydrotestosterone. Third, the extract and baicalin inhibited nuclear translocation of the androgen receptor stimulated by dihydrotestosterone in human dermal papilla cells. Additionally, the extract and baicalin enhanced proliferation of human dermal papilla cells in vitro. These results show that the extract and baicalin inhibited androgen activation signaling and promoted hDPC proliferation, suggesting that they could be used as active ingredients for treating androgen-associated disorders, such as androgenetic alopecia.

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Molecular dynamics (MD) simulations with the umbrella sampling (US) method were used to investigate the properties of micelles formed by sodium lauryl ether sulfate with two ether groups (SLE2S) and behaviors of corresponding surfactants transferring from micelles to ceramide and DMPC bilayer surfaces. Average micelle radii based on the Einstein–Smoluchowski and Stokes–Einstein relations showed excellent agreement with those measured by dynamic light scattering, while those obtained by evaluating the gyration radius or calculating the distance between the micelle sulfur atoms and center of mass overestimate the radii. As an SLE2S micelle was pulled down to the ceramide bilayer surface in a 400 ns constant-force steered MD (cf-SMD) simulation, the micelle was partially deformed on the bilayer surface, and several SLE2S surfactants easily were partitioned from the micelle into the ceramide bilayer. In contrast, a micelle was not deformed on the DMPC bilayer surface, and SLE2S surfactants were not transferred from the micelle to the DMPC bilayer. Potential of mean force (PMF) calculations revealed that the Gibbs free energy required for an SLE2S surfactant monomer to transfer from a micelle to bulk water can be compensated by decreased Gibbs free energy when an SLE2S monomer transfers into the ceramide bilayer from bulk water. In addition, micelle deformation on the ceramide bilayer surface can reduce the Gibbs free energy barrier required for a surfactant to escape the micelle and help the surfactant partition from the micelle into the ceramide bilayer. An SLE2S surfactant partitioning into the ceramide bilayer is attributed to hydrogen bonding and favorable interactions between the hydrophilic surfactant head and ceramide molecules, which are more dominant than the dehydration penalty during bilayer insertion. Such interactions between surfactant and lipid molecule heads are considerably reduced in DMPC bilayers owing to dielectric screening by water molecules deep inside the head/tail boundary between the DMPC bilayer. This computational work demonstrates the distinct behavior of SLE2S surfactant micelles on ceramide and DMPC bilayer surfaces in terms of variation in Gibbs free energy, which offers insight into designing surfactants used in transdermal drug delivery systems and cosmetics.