Beyond temperature: controlling collagen fibrillogenesis under physiological conditions via interaction with cucurbit[7]uril.

Under physiological ionic strength and pH, temperature has long been appreciated as the only stimulus that can be applied to induce in vitro self-assembly of tropocollagen. Here, we report a second, mechanistically new control strategy that uses non-covalent and selective binding of cucurbit[7]uril, a macrocyclic cavitand, with midchain aromatic residues on the tropocollagen surface. This strategy directly demonstrates the decisive role hydrophobic interactions play in collagen fibrillogenesis. It also points the way to the temporally-controllable formation of collagen fibrils in vivo that is highly desirable, yet challenging, in some biomedical scenarios.