Design and applications of man-made biomimetic fibrillar hydrogels

Many extracellular matrices (ECMs) have a filamentous architecture, which influences cell growth and phenotype and imparts tissues with specific properties. Man-made fibrillar hydrogels can function as biomimetic materials to reproduce the filamentous nature and properties of ECMs and to serve as scaffolds for 3D cell culture and tissue engineering. Different types of synthetic nanofibrillar hydrogels have been developed, with diverse mechanisms of assembly and a variety of physical properties and applications. In this Review, we explore the design and properties of biomimetic man-made nanofibrillar hydrogels. We discuss the assembly of peptides, block copolymer worm-like micelles and filamentous nanoparticles into fibrillar hydrogels and investigate the relationship between structure and physical as well as biochemical properties. Potential applications for 3D cell culture and tissue engineering are examined, and the properties and structure of natural and man-made fibrillar hydrogels are compared. Finally, we critically assess current challenges and future directions of the field. Man-made fibrillar hydrogels mimic the structure of filamentous extracellular matrices and can be used as biomaterials for 3D cell culture and tissue engineering. In this Review, the authors discuss the design and properties of fibrillar hydrogels and explore different building blocks, assembly mechanisms, properties and applications.