Tailoring the mechanical properties of nanoparticle networks that encompass biomimetic catch bonds

Abstract

Biological "catch" bonds display the distinctive attribute that the bond lifetime can increase under an applied force. Insertion of biomimetic catch bonds into hybrid materials could lead to composites that exhibit remarkable mechanical properties. We model the tensile behavior of polymergrafted nanoparticle (PGN) networks interconnected by a mixture of catch bonds and conventional "slip" bonds, whose lifetimes decrease with force. We formulate a kinetic master equation that provides the complete probabilistic description of a system of two PGNs. The master equation is used to analyze the parameter space that determines the rupture behavior of the catch bonds in the two-particle system. We then utilize two exemplary sets of catch bond parameters in threedimensional computer simulations of larger PGN networks under strain-controlled tensile deformation. We demonstrate that the strain at break and toughness of the networks can be altered by "tuning" the attributes of the catch bonds and varying the fraction of catch bonds in the network. We show that networks encompassing the catch bonds could exhibit a several-fold increase in the strain-at-break and toughness relative to those interconnected solely by the slip bonds. Our studies can provide valuable guidelines for tailoring the mechanical properties of novel, bio-inspired nanocomposites.

Detailed Balance Broken by Catch Bond Kinetics Enables Mechanical‐Adaptation in Active Materials

“…These results highlight the role of catch-bonds on fluidity, as well as rigidity, as the latter is principally observed in synthetic systems. [14][15][16][17][18] Furthermore, the non-monotonic change in material fluidity is also observed in biochemical reconstitution experiments that closely resemble our simulations. In the experiments, we alter the "effective" catch through the increase in motor content or F-actin crosslinking by α-actinin ( Figures S9 and S10, Supporting Information).…”

“…[ 13 ] In synthetic systems, mechanical load is applied externally, and catch bonds can increase the mechanical toughness of the material in response, enabling several‐fold increase in allowable strain. [ 14–18 ] While catch bonds in biological systems are also subject to external forces, [ 13 ] active stresses in living matter are generated internally, and the force generating units, in turn, sense and adapt to applied load. [ 19 ] If the source of the endogenous stress also acts as a catch bond, biological activity creates an adaptive feedback between macroscopic mechanical properties and microscopic, internal stress generation.…”

A Simple Mechanical Model for Synthetic Catch Bonds

“…As reversible interactions that become stronger with applied force, catch bonds can provide resistance to large mechanical stresses while allowing reconfiguration under small stresses in material systems. In particular, catch bonds have been shown, theoretically and computationally, [12][13][14][15] to enhance the mechanical properties of nanoparticle networks in nanocomposites. Certain non-biological molecules have been synthesized to mimic catch bond behavior.…”

Self-strengthening biphasic nanoparticle assemblies with intrinsic catch bonds

“…Given that catch bonds are reversible interactions that become stronger with applied force, they appear to be excellent candidates both for providing resistance to deformation and for enabling reconfiguration in material systems. While catch bonds have been shown theoretically and computationally 15 – 17 to enhance mechanical properties of network nanocomposites, and certain nonbiological molecules seem to exhibit catch bond behavior 18 , 19 , integration of catch bonds in materials has not yet been realized as structures with highly tunable catch bond-like characteristics have not yet been fabricated. So far, the catch bond research has led to the development of several theoretical models 20 , 21 .…”