Optimization of plant oil-based nanoemulsions prepared via phase inversion temperature and evaluation of their antioxidant capacity

Abstract

This study focuses on the preparation, and optimization of the nanoemulsions coorporating with pumpkin seed oil, grape seed oil, and grapefruit essential oil using the phase inversion temperature (PIT) technique. The research investigated the impact of surfactant types and concentrations on critical nanoemulsion properties, including droplet size, polydispersity index (PDI), and zeta potential. Using a Box-Behnken Design (BBD) model, the formulation was optimized containing 6.0% plant oils, 10.0% Tween 80, 2.0% Span 80, and 1.0% lecithin to achieve nano-sized droplets (33.52 ​nm), with a low PDI (0.205), and a stable zeta potential (−15.49 ​mV). The antioxidant activity, was evaluated through 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays, demonstrating its outstanding efficacy. And the optimized nanoemulsion showed a radical-scavenging capacity exceeding 2250 ​μg ascorbic acid equivalents/g, significantly outperforming non-nanoemulsified oils. Stability testing under various environmental conditions highlighted exceptional robustness, with refrigerated samples maintaining structural integrity, minimal particle size growth, and consistent physicochemical properties over a 30-day storage period. The results suggest that the plant oil-based nanoemulsions exhibit strong antioxidant potential, offering a promising natural treatment for their application in cosmeceutical and therapeutic formulations.