Dansuk and Keten have demonstrated that a simple mechanical design based on a tweezer-like mechanism can exhibit catch bond characteristics under thermal excitations. By introducing a switch design with broader energy landscape than the ligand binding site landscape, they achieve force-dependent kinetics that prolongs ligand lifetime through formation of secondary interactions. This serial arrangement of a soft conformational switch with a stiff ligand interaction results in catch bonds. The force versus lifetime curves are tunable by changing these design parameters.

Protein–ligand complexes with catch bonds exhibit prolonged lifetimes when subject to tensile force, which is a desirable yet elusive attribute for man-made nanoparticle interfaces and assemblies. Most designs proposed so far rely on macromolecular linkers with complicated folds rather than particles exhibiting simple dynamic shapes. Here, we establish a scissor-type X-shaped particle design for achieving intrinsic catch bonding ability with tunable force-enhanced lifetimes under thermal excitations. Molecular dynamics simulations are carried out to illustrate equilibrium self-assembly and force-enhanced bond lifetime of dimers and fibers facilitated by secondary interactions that form under tensile force. The non-monotonic force dependence of the fiber breaking kinetics is well-estimated by an analytical model. Our design concepts for shape-changing particles illuminates a path towards novel nanoparticle or colloidal assemblies that have the passive ability to tune the strength of their interfaces with applied force, setting the stage for self-assembling materials with novel mechanical functions and rheological properties.

Chaperone-Usher pilus with catch bond adhesin—a bacterial biopolymer with the ability to attach to biotic/abiotic surfaces—can act as a “molecular seat belt” that has tunable cohesive strength and rate-responsive behavior.