The underlying molecular mechanism of topical fluid foam with microsphere assistance

Topical fluid foam has a considerable application value in the field of topical medicine due to its advantages such as simple uniform distribution on the skin's surface, ease of use, and good patient compliance. The longevity of topical fluid foam is crucial in assessing its therapeutic success, particularly in complicated heat and salt settings. Nanoparticles could improve the stability of topical fluid foam, but their density, size, homogeneity, and surface characteristics are difficult to take into consideration simultaneously, resulting in an unclear underlying molecular mechanism. In this work, raspberry-like microspheres (RMs) with a high cross-linked structure were synthesized using a simple one-step dispersion polymerization method. The stabilizing foam function of RMs in fluid foam was connected to their size, surface chemical characteristics, and foaming temperature. The effect of gravity on foam stability induced by liquid flow acceleration of RMs competed fiercely with their size and surface chemical characteristics, and this competitive connection was highly influenced by temperature. The unique surface properties of RM₁ (polymerization time of 1 h) allowed for its irreversible adsorption at the gas-liquid interface following sodium dodecyl sulfate (SDS) adsorption. RM₁ could counteract the harmful effect of gravity on foam stability at a high temperature of 60 °C, enhancing the surface elasticity of the liquid film and improving the foam stability. This work is a fantastic starting point for the development of novel nanomaterials to improve the stability of topical fluid foam for pharmaceutical and medical applications.