Nanolignin and Nanochitin as Skin-Friendly Biopolymer Carriers for Innovative Cosme-Nutraceuticals: A Review

Lignin and chitin are abundant structural biopolymers that can be recovered from wood-processing, agricultural, fishery and other biological residues. Their conversion into nanoparticles, nanocrystals or nanofibrils provides opportunities to combine carrier functions with properties intrinsic to the polymers. This review examines the chemical structures, biological organization, isolation routes and nanostructuring methods of lignin and chitin, and relates these features to their potential use in cosmetic and nutraceutical delivery systems. Particular attention is given to the influence of raw material source and processing on particle morphology, surface chemistry, colloidal stability and functional performance. The UV-screening and antioxidant properties of nanolignin are discussed alongside the structural and surface-charge characteristics of nanochitin. Polyelectrolyte complexation is considered as an assembly strategy within this broader framework, with examples based on either polymer or chitin nanofibril–nanolignin complexes. Electrospun non-woven carriers and related delivery formats illustrate how these materials can be incorporated into functional products. Finally, the review identifies the characterization, safety, regulatory, manufacturing and environmental challenges that must be addressed before these very promising materials can be widely used in cosmetic and nutraceutical applications.