Electrochemically extracted nanocellulose from durian peel as a biocompatible carrier for diclofenac delivery

Durian peel, a lignocellulosic by-product abundantly generated in Southeast Asia, was valorized as a sustainable source of nanocellulose for pharmaceutical applications. A green electrolysis-assisted extraction approach, employing NaCl as both electrolyte and in situ acid generator, was optimized using response surface methodology. The process yielded cellulose with a crystallinity index of 61.2%, enhanced thermal stability (T_d = 335 °C), and a specific surface area of 14.4 m²/g. Subsequent acid hydrolysis and ultrasonication produced cellulose nanoparticles (CNPs, 100-300 nm) with stable surface charge (pH_pzc = 6.6). The adsorption of diclofenac sodium (DCF) onto CNPs followed pseudo-second-order kinetics (R² = 0.9996) and was best fitted by the Freundlich (R² = 0.952) and Dubinin-Radushkevich (E = 2.04 kJ/mol) isotherms, indicating multilayer physical adsorption. Drug release exhibited zero-order and Korsmeyer-Peppas kinetics (n = 0.90-1.89), demonstrating sustained and pH-responsive release in gastric (pH 1.2), intestinal (pH 6.8), and plasma (pH 7.4) media. The CNPs showed excellent biocompatibility, with hemolysis <0.75%, non-irritancy in HET-CAM assays, and strong mucoadhesion (55%). This study introduces a scalable, environmentally benign strategy for producing biocompatible nanocellulose carriers from agro-waste, offering significant potential for controlled oral and parenteral drug delivery systems.