Dr. Bizan Balzer: "Stereographic force spectroscopy: a tool to study the directional anisotropy of molecular systems"
Institute of Physical Chemistry, Cluster of Excellence livMatS @ FIT and FMF
University of Freiburg, Germany
The atomic force microscope (AFM) is a versatile tool for imaging and force spectroscopy at the nanoscopic to mesoscopic scale. It is used to understand adhesion and friction properties of molecular systems and polymer mechanics in liquid environment.
Based on the development of functionalization protocols for covalent binding of single polymers to AFM cantilever tips  the adhesion and mechanics of single polymers has been studied on a great variety of solid substrates under liquid conditions.[2,3] Now we have extended this method towards stereographic force spectroscopy using angle-dependent pulling to monitor direction dependent properties of single polymers.[4,5]
Here, I will present stereographic force spectroscopy of single polymers to study the multidirectional and velocity dependent rupture of covalent bonds, coordination bonds and π-π stacking as well as receptor-ligand-protein complexes.
Our studies are fundamental to understand the role of force application direction for molecular adhesion and friction. This will help to discover the molecular origin of adhesion and friction and to design substrates with optimized interfacial properties.
 Kolberg et al., J. Vis. Exp., 157, e60934 (2020).
 Horinek et al., PNAS, 105(8), 2842–2847 (2008).
 Kolberg, et al., J. Am. Chem. Soc., 141 (29), 11603 (2019).
 Balzer et al., Angew. Chem. Int. Ed. 52,25, 6541 (2013).
 Balzer et al., Soft Materials 12, S106-S114 (2014).