Solid‐phase molecular self‐assembly facilitated supramolecular films with alternative hydrophobic/hydrophilic domains for skin moisture detection

Abstract

Human skin moisture is closely related to health and personal care issues. Many creams were developed to claim capable of skin moisturizing. However, people can hardly check their skin moisture status and the moisturizing effect of various creams conveniently, since currently all the skin moisturizing detection rely on large equipment requiring power supply. Herein, we report a power-supply independent supramolecular film that is able to directly report the moisturizing status of the skin. With the strategy of solid-phase molecular self-assembly (SPMSA), the aqueous precipitates formed by commercially available polyelectrolyte and oppositely charged surfactant would transform into a supramolecular film under a mild mechanical pressure, where the hydrophobic surfactant domains bridged by polyelectrolyte merge into hydrophobic mesophases to reduce interfacial energy. The hydrophobic mesophase will greatly retard water diffusion inside the film, so that a humidity gradient is generated as the film is exposed to a humid environment. The film will bend upward automatically in touch with moisture skin, and the bending degree is proportional to the skin moisture status. Therefore, the film can be used as portable smart power-free skin moisture sensor.

Effect of the Molecular Weight of Polyelectrolyte and Surfactant Chain Length on the Solid-Phase Molecular Self-Assembly

“…These distances are about 2 times of the increasing length of the corresponding surfactants (SDS ≈ 1.7 nm, SDeS ≈ 1.5 nm). FT-IR measurements (Figure b) revealed that the symmetric and asymmetric vibration band for the alkyl chains in the PDDA-SDS and PDDA-SDeS films occurred at 2852, 2922, and 2854, 2924 cm –1 , respectively, manifesting the alkyl chains packed less orderly as it becomes shorter. , …”

“…Under mild mechanical pressure and in the presence of physically adsorbed water to facilitate molecular rearrangement, the caking in the PE/surfactant precipitates leads to a self-supporting supramolecular film, where the surfactant bilayers were bridged by the PE chains to form continuous macroscopic structures. This not only allows the preparation of noncolloidal form self-supporting macroscopic molecular self-assembled materials but also makes it possible to get diversified functions. ,,,− ,,, However, we found that the film formation ability and the resultant mechanical strength of the film depend highly on the surfactant and polyelectrolyte structure, in particular, the surfactant chain length and the molecular weight of the PE. In order to reveal the physical insight behind this effect, herein, we report a systematic study of the films formed with sodium alkyl sulfates and poly dimethyl diallyl ammonium chloride (PDDA).…”

“…Inspired by this phenomenon, recently, our group postulated the strategy of solid-phase molecular self-assembly (SPMSA), − which elegantly utilizes the caking tendency of particles in precipitates formed with molecules with self-assembly ability, in particular, precipitates formed with a surfactant and an oppositely charged polyelectrolyte (PE) . Under mild mechanical pressure and in the presence of physically adsorbed water to facilitate molecular rearrangement, the caking in the PE/surfactant precipitates leads to a self-supporting supramolecular film, where the surfactant bilayers were bridged by the PE chains to form continuous macroscopic structures.…”

A fluorescent film sensor for high‐performance detection of Listeria monocytogenes via vapor sampling

“…Compared to other techniques, excited-state processbased [26][27][28][29] and small molecule-related [30][31][32][33] fluorescent techniques, especially those based on fluorescent films, [34][35][36][37][38][39][40][41][42][43] demonstrate great sensitivity, improved selectivity, and unprecedented designability. For film-based fluorescent sensors, however, the films must be highly porous and photochemically stable, as they are necessary for sensitive, reversible, and applicable sensing.…”

Revealing Mitochondrion–Lysosome Dynamic Interactions and pH Variations in Live Cells with a pH-Sensitive Fluorescent Probe

“…17−19 Therefore, a thorough understanding of intricate dynamic interplays between mitochondria and lysosomes might provide insights into the underlying mechanisms of many diseases and pave the way for the development of novel therapeutic strategies. Organic small-molecule fluorescent probes are currently recognized as powerful tools in the field of highly sensitive detection 20,21 and live-cell imaging. 22,23 Remarkably, they facilitate the visualization and analysis of organelle dynamics and interactions.…”