Heterotypic supramolecular hydrogels

Abstract

Supramolecular hydrogels, formed via intermolecular interactions in water, are emerging as a new type of versatile soft materials to be applied in many areas, such as biomedical applications, catalysis, food additives, and cosmetics. While most of the supramolecular hydrogels are homotypic (i.e., one type of building block), heterotypic supramolecular hydrogels are less explored, but may offer unique advantages. This review describes supramolecular hydrogels that consist of more than one type of building block (i.e., heterotypic) to illustrate the promise and challenges of heterotypic supramolecular hydrogels as soft biomaterials. First, we discuss the driving forces for producing heterotypic supramolecular hydrogels. Second, we introduce the general methods for triggering heterotypic supramolecular hydrogels. Third, we summarize examples of heterotypic supramolecular hydrogels made of hydrogelators with or without amino acid residues. Fourth, we describe the applications of heterotypic supramolecular hydrogels to date. Finally, we give an outlook and propose a few future directions that likely are worthy to explore.