Synthetic catch bonds
All primary chemical bonds, covalent and supramolecular, weaken under tension. This imposes fundamental limits on the mechanical stability of molecules and their materials. Nature has evolved to secondary bonds that break through these limits and strengthen under tension. These so-called catch bonds, which know no synthetic equivalent to date, are used in Nature as a rule, rather than exception, in scenarios where supramolecular bonds are exposed to large stresses.   This change in the fundamental mechanical nature of bonds has a profound effect on the mechanics of the materials in which they are integrated. Yet, to date, there have been no systematic studies that establish how the mechanics of individual catch bonds is programmed by their chemical design or how their collective action results in enhanced mechanics of their materials. As a result, our understanding of the ubiquitous use of catch bonds in Nature is incomplete nor do we have clear guides how their potential can be harnessed in creating bio-mimetic soft materials with programmable mechanics.  Project CATCH tackles these challenges by bringing catch bonds to the synthetic domain for the first time. Their de-novo creation gives unprecedented control to establish the design rules for the mechano-activity of single bonds. Moreover, CATCH will systematically explore how the concerted action of many catch bonds within a material lead to material properties that cannot be accessed by any other means, such as the adaptive reduction of strain localisation and the filtering of mechanical signals, which is of crucial importance for mechanical communication between cells in tissue engineering.  Through a multidisciplinary approach that builds on my expertise in synthetic and materials chemistry, single-molecule experiments, and multiscale mechanical experiments and modelling, this project will decipher and harness one of Nature’s most ubiquitous, but poorly understood, mechanical design strategies.