Surface-engineered nanocellulose for enhanced antibacterial activity and biomedical applications.

Antimicrobial resistance (AMR) and biofilm-associated infections create a need for locally active biomaterials that can combine bacterial killing with tissue compatibility and controlled antimicrobial exposure. Pristine nanocellulose has limited intrinsic antibacterial activity; therefore, its biomedical value depends primarily on surface engineering and integration with antibacterial agents. This review critically evaluates chemical functionalization, antibiotic loading, nanoparticle integration, and bioactive-polymer conjugation using a structure-activity framework that links surface charge, functional-group density, porosity, crystallinity, drug loading, and release kinetics to antibacterial and antibiofilm outcomes. "Representative evidence demonstrates substantial modification-dependent antibacterial and antibiofilm effects, including approximately 99% bacterial reduction by APTMS-functionalized films, a minimum inhibitory concentration of approximately 50 μg/mL for sulfate-functionalized nanocellulose, and approximately 95% antibiofilm inhibition by ciprofloxacin-loaded carbonized nanocellulose." Because antibacterial endpoints are strongly assay-dependent, the reported findings are interpreted in relation to study-specific controls rather than as directly comparable potency measures. The novelty of this review is the integration of modification chemistry, antibacterial mechanism, quantitative efficacy, physicochemical determinants, biosafety, and translational feasibility; extraction methods are discussed only when they alter antibacterial-relevant material attributes. Current barriers include incomplete standardization of antibacterial assays, insufficient coupling of release kinetics with cytocompatibility, residual-reagent and nanoparticle toxicity, sterilization stability, batch reproducibility, and scale-up. Surface-engineered nanocellulose is therefore best considered a tunable antibacterial platform whose clinical and commercial value will depend on reproducible structure-activity-safety relationships.