Weak yet specific bonds challenge our current fundamental physics understanding, while holding many exciting prospects for materials science. For example, one could tether non-covalent binding groups to the surfaces of nano-particles to steer their spontaneous self-assembly into functional structures. Additionally, the tether properties and the typically multi-bond nature of weak-bond interactions give rise to novel 'adaptive' materials that can dynamically respond to external stimuli - much like biological matter, but markedly different from the static nature of traditional man-made materials, which are based on strong bonds. The realization of such applications poses a major challenge though, as the physics of collections of tethered weak bonds is poorly understood. Our goal is to tackle this fascinating physics problem in a systematic and quantitative way and to unravel how the interactions depend on the individual bond properties and multi-bond effects, as well as the implications for macroscopic adhesion, self-organization and material properties. To make this possible, our idea is to employ synthetic DNA constructs as model weak bonds, in combination with recently developed ultra-sensitive force probe and microscopy techniques. Our designer bonds will offer unprecedented control over the essential parameters, including the bond length, strength and flexibility, the energy landscape of the binding site, as well as specific conformational changes. This will allow us to push the quantitative physics understanding past the more commonplace single-molecule measurements and theoretical approximations. The proposed projects will focus on the physics of (1) single- and multi-bond entropic effects, and (2) special bonds with multi-well energy landscapes or unusual mechanical response; including so-called catch bonds that (counter-intuitively) become stronger when mechanically stressed. The insight gained will advance the understanding in various fields, including soft condensed matter physics and biophysics, and should guide the design of innovative applications based on weak bonds.
Anders dan de meeste kunstmatige materialen kunnen biologische materialen zich dynamisch aanpassen aan hun omgeving door middel van zwakke bindingen die continu breken en opnieuw vormen. De onderzoekers gaan de algemene natuurkundige eigenschappen van zulke zwakke bindingen ontrafelen met nieuwe, uitzonderlijk goed controleerbare modelsystemen van synthetisch DNA.