Institute of Solid State Physics

SS22 WS22 SS23 WS23 SS24 WS24      Guidelines for Master Students

Evaluating nanoscale contact and adhesion using FRET microscopy
Ulrich Hirn, M. Gaspar-Simoes. G. Urstöger, R. Schennach
11:15 - 12:15 Wednesday 11 January 2023 ph01150

Several intermolecular mechanisms are responsible for adhesion: hydrogen bonding, van der Waals forces and electrostatic interaction. Among these mechanisms hydrogen bonding and van der Waals attraction only work if molecular contact -- i.e. a distance between surfaces below a few angstrom -- is achieved. Thus, the area of molecular contact is the most important factor determining the strength of adhesion. In fact it is a multiplier to all the molecular mechanisms, an increase in contact area leads to a directly proportional increase in bonding energy.


FRET (Förster Resonance Energy Transfer) fluorescence is a technique where fluorescence energy between dyes can only be transmitted when the dyes molecules are in close distance in the nanometer range. We are using this technique to quantify the degree of nanoscale contact between polymeric surfaces. For p-Hema thin films we have been able to demonstrate a direct relation between the adhesion force and the adhesion contact area evaluated as FRET intensity. Challenges and results in adapting this method for evaluating molecular contact between cellulosic surfaces are presented and discussed.