Improved chitosan–cellulose nanofibrils hybrid polymer composite gels from prickly pear cactus

Abstract

Petroleum-derived materials present low biodegradability and considerable environmental impact, which has driven the search for sustainable alternatives. In this context, the aim of the present study was to develop a nanocomposite gel with enhanced properties by incorporating chitosan into cellulose nanofibrils (CNF) obtained from prickly pear cactus. CNF were produced by alkaline treatment followed by mechanical defibrillation. Different concentrations of chitosan (0%, 1%, 5%, and 10%) were then incorporated into the CNF, and the resulting polymer composites were evaluated for their morphological, rheological, and antimicrobial properties. CNF produced without chitosan (CNF-0%) exhibited an average diameter of 27.53 ± 5.25 nm, while chitosan addition increased fibril diameter up to 59.19 nm (CNF-10%). All samples were characterized by pseudoplastic behavior (flow index n < 1). Thermal stability was maintained up to 60 °C, with consistent viscoelastic behavior across treatments. CNF-1% chitosan formulation displayed antimicrobial activity against Pseudomonas aeruginosa and outperformed the other formulations by combining improved structural and rheological properties with selective antimicrobial activity, underscoring its potential for biodegradable coatings in food and pharmaceutical applications.