Green Synthesis and Characterization of Chitosan-Organoclay Biocomposite Functionalized with Antioxidant Extracts: Enhancing Bioactivity and Controlled Release

Abstract

Contaminants can penetrate the skin and generate reactive oxygen species (ROS), including free radicals which induce oxidative stress. Incorporating antioxidants into skincare formulations is an effective strategy to reduce free radicals, but conventional antioxidants often suffer from uncontrolled release. Here, for the first time, an eco-friendly chitosan/pomegranate peel extract (Ch–PPE) biocomposites intercalated into Gemini-modified montmorillonite (OMMT) were synthesized to develop a multifunctional and biodegradable skincare formulation (CPOM). Structural and physicochemical analyses (XRD, FTIR, FE-SEM, TGA/DTG, DSC) confirmed successful intercalation and stable surface characteristics, indicating effective hybridization. Increasing PPE content enhanced bioactivity, with Ch–PPE 15% exhibiting the highest total phenolic content (298 mg GAE/g), total flavonoid content (100.26 mg QE/g), and radical scavenging activity (83.21%), accompanied by reduced moisture content, reflecting improved structural stability. The CPOM formulation blocked over 90% of UV-B radiation and showed sustained release, with the release kinetics best described by the Korsmeyer–Peppas model at both pH values. Antibacterial testing against E. coli demonstrated 54.30% ± 0.32 colony reduction, while cytotoxicity assays confirmed dose-dependent safety, maintaining > 80% cell viability below 0.12 mg/mL. IC₅₀ values highlighted higher bioactivity of CPOM (0.17 mg/mL for HaCaT; 0.19 mg/mL for HFF) compared to PPE alone. These findings demonstrate that CPOM biocomposites act as stable, multifunctional carriers combining antioxidant, UV-protective, antibacterial, and controlled-release properties, representing a promising strategy for advanced multifunctional skincare formulations.