Protein-Based Encapsulation Strategies: Toward Micro- and Nanoscale Carriers with Increased Functionality

Proteins and peptides are attractive chemical building blocks to encapsulate and protect active substances thanks to their biocompatibility, biodegradability, low immunogenicity, and added functionality compared to synthetic polymers. This review provides a comprehensive overview of micro- and nanocapsules predominantly made of proteins—both natural and artificially produced—and peptides, detailing their different fabrication techniques and possible applications in various fields, including food technology and healthcare. Emphasis is given on the capability of proteins and peptides to assemble into capsular structures in the absence (e.g., protein cages and polypeptide-based coacervates) or presence of a template, as well as on the physical nature of the carriers core, i.e., gaseous, liquid, or solid.