Potential for integrating enzymatic and conventional approaches in lignin nanoparticle production from oil palm biomass

Oil palm processing generates substantial lignin-rich residues that remain underutilized. Converting this lignin into nanoparticles (LNPs) offers sustainable applications in biomedicine, materials, and remediation. Conventional extraction and synthesis methods often involve harsh chemicals or high energy input, which alter lignin's functional groups and raise environmental concerns. Enzymatic methods, using laccases, peroxidases, and auxiliary oxidases, operate under mild conditions and preserve phenolic and aliphatic functionalities. This review examines physical, chemical, and enzymatic strategies for LNP production, highlighting their effects on particle properties and environmental impact. Major approaches include solvent exchange, acid precipitation, ultrasonication, and homogenization, combined with enzymatic surface modification. It also outlines characterization methods and potential applications in drug delivery, UV protection, antioxidant activity, and pollutant adsorption. Challenges remain in enzyme cost, stability, and lignin variability. Future research should prioritize enzyme engineering, process intensification, and integration with deep eutectic and ionic liquids to support a sustainable circular bioeconomy.