Speciale forsvar: René Brüggebush Svensson

"Mechanical properties of single collagen fibrils investigated by atomic force microscopy"

In this thesis, an atomic force microscopy (AFM) approach is developed for mechanically testing individual collagen fibrils from tendon. Fibrils are long thread-like superstructures formed by the protein collagen, and are the primary building blocks of numerous structural tissues in mammals including bone, skin and tendon. The fibrils have diameters in the range of a few hundred nm, and the ability to mechanically test such small structures has only recently emerged.
The developed method is based on freely suspending the collagen fibril between an AFM cantilever and a substrate, using an epoxy adhesive. This makes it possible to stretch the fibril with the AFM scanner while using the cantilever bending as a force gage.
In the defence, the method will be described in details and preliminary results will be presented on two types of experiment. One involves the biochemical modification of collagen fibrils with a cross-linking agent (glutaraldehyde). The other is an investigation of viscoelastic behaviour performed by testing at different rates.