Supramolecular nanofibrillar polymer hydrogels

Abstract

Nanofibrillar supramolecular hydrogels are hierarchical structures formed by physical association of high-aspect-ratio nanoscale building blocks, each containing many molecules held together via supramolecular interactions. Nanofibrils have diameters in the range of tens to hundreds of nanometers, and their lengths can exceed micrometers. The driving forces involved in the formation of nanofibrillar structures include hydrogen bonding, hydrophobic forces, forces of electrostatic origin, and guest–host interactions. Nanofibrillar hydrogels are formed by biopolymers such as proteins and polysaccharides, and by synthetic supramolecular units such as cylindrical micelles of block copolymers and peptide amphiphiles. In the present review, we discuss the hierarchical assembly of nanofibrillar hydrogels, give examples of hydrogels formed by the most important groups of polymers, discuss structure–property relationships of these nanofibrillar hydrogels, and review their current and potential applications in the fields of bioengineering, cell biology, medicine, and cosmetics.