LAUSR

Summary Complex biomaterials easily formed by self-assembling proteins could transform regenerative medicine and 3D cell culture. However, although readily achieved by short peptides, materials assembled from proteins with a defined tertiary structure are still rare. The bacterial fimbrial protein, capsular antigen fragment 1 (Caf1), forms long polymers of subunits linked by kinetically stable non-covalent interactions, which can be further chemically crosslinked into a variety of hydrogels. We report here that the complete thermal dissociation of Caf1 polymers or hydrogels into individual subunits is fully reversible with high yield. This simple feature endows the Caf1 polymer with outstanding synthetic and materials possibilities and, to demonstrate, we describe the in vitro assembly of complex bioactive copolymers and provide example applications of meltable protein hydrogels. We anticipate that the highly efficient and reversible assembly of these multifunctional polymeric proteins will enhance significantly the development of proteinaceous biomaterials for clinical and industrial applications.