Evaluation of nonionic surfactant-based emulgels as a prospective approach for skincare products

Abstract

This study aimed to develop and evaluate emulgels with potential applications in skincare formulations, utilizing nonionic surfactants as the primary emulsifying agents. Emulgels were prepared using matrix-forming agents and a controlled homogenization process involving oil and water phases. Comprehensive analyses were conducted to characterize the emulgels, including microscopic evaluation, physicochemical property assessments (pH, density, and acidity index), stability tests (thermal and centrifugation), droplet size distribution analysis, contamination assessments, and oscillatory rheology (amplitude and frequency). Additionally, sensory and topography analyses by Atomic Force Microscopy (AFM) were performed to evaluate their applicability in cosmetic formulations. While the proportions of gelling agents, oil (cherry kernel, black currant, grape, and peanut oils), and water remained constant, the stability of the formulations was mainly influenced by the concentration of nonionic surfactants, including polyethylene glycol 1000 (PEG 1000), polysorbate 60 (Tween 60), and coco-glucoside. Experimental data confirmed that all emulgels maintained stability at 25 °C and 4 °C, which was related to the absence of phase separation. The formulations exhibited a low polydispersity index (below 0.35 ± 0.01) and a highly negative zeta potential (up to −38.67 ± 1.23 mV). Notably, all formulations were classified as classical colloid systems, with 90 % of the droplet sizes under 1000 nm. Notably, emulgels containing PEG 1000 and coco-glucoside showed an even finer dispersion, with all droplets measuring under 1000 nm. Overall, our findings provide a solid framework for designing and optimizing nonionic surfactant-based emulgels, offering innovative and stable solutions for advanced skincare applications.