Designing chitosan-coated niosomes: advanced encapsulation strategies to control drug release, enhance stability, and improve therapeutic efficacy.
TL;DR
Findings establish chitosan-coated, cholesterol-Tween niosomes as versatile, biocompatible carriers that provide sustained release and preserve bioactivity, with promising potential for ocular drug delivery and broader biomedical applications.
Abstract
Nanocarrier-based drug delivery systems have gained considerable attention for enhancing the therapeutic efficacy of bioactive compounds with poor physicochemical properties. Polyphenols such as quercetin and resveratrol exhibit potent antioxidant, anti-inflammatory, and anticancer activities; however, they suffer from poor bioavailability. To address this limitation, we prepared cholesterol-based niosomes using the Tween 20, Tween 40, and Tween 80 surfactants via thin-film hydration, followed by chitosan coating for enhanced stability. The formulations were characterised using dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and FTIR spectroscopy, which together confirmed the formation of spherical, nanoscale vesicles, successful chitosan deposition, and physical (non-covalent) entrapment of both drugs. Encapsulation efficiencies exceeded 70% across all systems. Among the formulations, the Tween 40 formulation consistently produced the smallest, most uniform vesicles and showed the highest cumulative drug release, while the Tween 20 and Tween 80 systems favoured stronger drug retention and more gradual release, suggesting the key role of the surfactant tail in controlling drug release. Encapsulation preserved the bioactivity of the polyphenols. Consequently, the drug-loaded niosomes retained strong radical-scavenging activity and reducing capacity, inhibited both Escherichia coli and Staphylococcus aureus (with stronger activity against Gram-negative E. coli), and markedly suppressed the oxidative stress-induced aggregation of γD-crystallin, a key event in cataract formation. MTT assays confirmed their good biocompatibility. Collectively, these findings establish chitosan-coated, cholesterol-Tween niosomes as versatile, biocompatible carriers that provide sustained release and preserve bioactivity, with promising potential for ocular drug delivery and broader biomedical applications.