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Bending single collagen fibrils with atomic force microscopy
This project can be a MSc (45 ec) or BSc (15 ec) project and is a joined effort of the Biophysical Engineering Group and the Polymer Science and Biomaterials group. Lanti Yang (l.yang@utwente.nl, +31 53 489 2968) |
Introduction
Collagen is the most abundant protein molecule present in the human body and provides rigidity and structure to connective tissue. Over the last decades, several studies have been directed towards the elucidation of the hierarchical structure of collagen and to relate the structure to its function and mechanical properties. Next to understanding the collagen structure and function within the human body (in vivo), these studies also focus on the use of collagen in implants.
Within our laboratory we have started tensile test experiments on individual collagen fibrils. To this end a 200-nm thick collagen fibril was attached with one end to the supporting surface and with the other end to the AFM tip. By moving the tip is upward direction, a force-distance curve can be measured, from which elastic and mechanical properties of the collagen fibril can be deduced. We also have developed a bending test in which the fibril is deposited on a surface that contains micrometer-sized channels. Part of the collagen fibrils will suspend freely over the channels. Using the AFM to press the fibril in the middle of the suspended part, the elastic and mechanical properties can be determined.
Project description
The assignment consists of performing experiments using this bending tests on differently treated collagen fibrils. The first measurements of fibrils in ambient (i.e. air) conditions have been done, but it is essential for the application of collagen as a structural material to study the change of elastic and mechanical properties when crosslinking is applied (with for example glutaraldehyde, EDC-NHS, …). This provides insight into the molecular mechanism of crosslinking, i.e. on what level of the hierarchical structure crosslinking actually has an effect. As a next step the tests need to be performed in a liquid environment.
Schematic representation of a microchannel across which a single collagen fibril has been deposited. The arrows indicate the positions where the AFM tip is brought into contact with the fibril.
