Polymersomes and their biological implications
Polymeric vesicles, also called polymersomes, are the synthetic analog of liposomes. Polymersomes are self-assembled structures composed of amphiphilic block copolymers instead of phospholipids as their natural counterparts. They provide enhanced variability as well as improved physical and chemical stability, owing to the good synthetic control in polymer chemistry. Water-soluble as well as lipophilic cargo can be embedded either in the hydrophobic part of the polymersomes' membrane or encapsulated in the hydrophilic inner lumen of the polymer vesicle. Many types of cargo such as dyes or drug molecules as well as inorganic nanoparticles such as iron oxide or gold colloids are feasible, leading to hybrid structures for versatile applications, which include theranostic approaches in biomedicine. Tunable membrane properties enable the generation of a controlled release of a therapeutic cargo triggered by external or internal stimuli. Even the incorporation of tunnel proteins has already been performed and polymersomes have been shown to be smart nanoreactors with controllable transport through their membrane. Furthermore, surface functionalization broadens the range of potential applications: specific targeting ligands attached to the polymersomes' surface can help to transport, for example, anticancer agents to the tumor tissue while protecting the surrounding healthy tissue from the highly cytotoxic drugs. This chapter briefly presents the basic principles of polymersome formation and different preparation methods. Furthermore, it gives an overview of the broad range of promising applications of polymeric vesicles, which includes - but is not limited to - polymersomes as smart drug carriers, theranostic multi-tools, and nanoreactors.