Nanomechanical characterization of supramolecular protein structures using atomic force microscopy


In this project we will further develop and use atomic force microscopy imaging, nanomechanical bending and nano-indentation on individual fibrillar protein aggregates and on the mesoscopic gels they form. The objective is to gain a better fundamental understanding of, and insight into, the relation between (i) the molecular properties of the individual protein molecule and the structural and mechanical properties of the resulting fibrillar structures and (ii) the properties of these fibrillar structures and the mechanical, structural and rheological properties of the solution of entangled, semi-flexible fibers on a mesoscopic scale.

The experiments will be complemented with computer simulations of two different types. In the first type we plan to simulate the bulk rheology of entangled networks given the structural and mechanical properties of its constituent fibrils. This will help us in creating a comprehensible link between the structural and mechanical properties on the different length scales. The second type of simulation will simulate the actual nano-indentation experiment, which will aid in understanding how to deduce relevant rheological parameters from the force distance curves obtained.


(A) Schematic representation of a ball-type tip to be used for nano-indentation experiments. (B) An example force distance curve. Grey line represents a force distance curve measured on a hard surface. Red line is an example on a biological, softer surface. Difference between the two curves (d) defines the indentation. (C) Pulsed force mode, where the force during the indentation is kept constant and the z position of the indentor is recorded.


Postdoc: Ramesh Subramani
Project leader: Martin Bennink

This project is in active collaboration with the Computational Biophysics Group (prof. Wim Briels) at the University of Twente.