Polycatechols: Promising materials for biomedical applications

Polycatechols are a class of polymers bearing multiple catechol moieties. These polymers possess unique physiochemical properties such as antioxidant, bioadhesive, metal chelating, and dynamic covalent bonding. As a result, polycatechols have shown great promise in various biomedical applications i.e. drug delivery, gene and protein delivery, free radical scavenging, antimicrobials, bio-adhesions, tissue engineering, and bioimaging. The polymers have strong binding affinities with biomolecules such as genes, proteins, phospholipids, and extracellular matrices via non-covalent interactions, and are proposed as effective carriers for biotherapy and bioadhesives for tissue engineering. The abundant catechol moieties on polycatechols allow strong free radical scavenging to treat oxidative stress and inflammation. In addition, polycatechols form dynamic covalent linkages with boronate ligands, and are used to modulate the quorum-sensing signaling in bacteria, or deliver anticancer drug bortezomib to tumor microenvironments. Besides, polycatechols coordinate with metal ions such as gadolinium (III) to provide contrast reagents for magnetic resonance imaging. In this critical review, currently developed synthetic methods for polycatechols and their physiochemical properties will be introduced. The design principles for polycatechols in detailed biomedical applications will be intensively described. Finally, current challenges and future perspectives in the development of next-generation polycatechols will be discussed.