Polymers for protein delivery

Proteins are the material basis of life, holding great potentials for the treatment of cancer, immunological diseases, and metabolic disorders. In the past decades, great achievements have been made to deliver active proteins to specific organs and cells. Polymeric vehicles have been widely developed to encapsulate proteins, protect them from denaturation and degradation, promote targeted delivery, enhance the transmembrane delivery efficiency, and control the protein release in targeted sites. This article presents an introduction of various polymer design strategies for extracellular and intracellular protein delivery according to the different sites where proteins perform their functions. Polymers for extracellular protein delivery are mainly developed to overcome opsonization, protease degradation, and mucosal barrier, as well as to enable controlled or sustained protein release. Polymers for intracellular protein delivery include polymer-protein conjugates, micelles, polymersomes, polymer-protein self-assembly, and polymerization-based nanocapsules that can mediate efficient protein encapsulation, cytosolic delivery, endolysosomal escape, and intracellular cargo release.