Nano-scale valorization of agro-industrial raw materials: Bionanocomposites from 4-aminobenzoic acid-modified cellulose nanofibers and wheat gluten protein.

This study explores the potential of using agricultural industrial byproducts to synthesize nanocomposite materials to address the increasing demand for sustainable alternatives to synthetic plastics. Cellulose nanofibers (CNF) were extracted from waste sugarcane bagasse (SCB) through chemo-mechanical treatment and subsequently esterified with 4-aminobenzoic acid (PABA) to obtain modified CNF (mCNF). Wheat gluten protein (WGP), plasticized with glycerol, was used to form films, incorporating CNF and mCNF as fillers. Comprehensive characterization revealed successful CNF functionalization and uniform dispersion within the protein matrix, confirmed through FTIR, UV-Vis spectroscopy, TGA, SEM, and confocal microscopy. The mCNF-reinforced films exhibited a 10× increase in tensile strength (47.98 MPa), a 35 % reduction in water vapor permeability, and improved thermal resistance by over 40 °C. Enhancement of red fluorescence in confocal images indicated improved dispersion and compatibility among mCNF and WGP matrix. To enhance functional performance, the films were coated with a chitosan-salicylic acid layer, resulting in effective antibacterial activity. This work introduces a simple yet scalable approach to transform agricultural waste into high-performance biodegradable films. By chemically modifying nanocellulose and applying a natural antimicrobial coating, we address major limitations of WG-based films.