Understanding and controlling type I collagen adsorption and assembly at interfaces, and application to cell engineering.

Collagen is a large anisotropic and self-assembling extracellular matrix protein. Understanding and controlling its adsorption and assembly at interfaces is expected to increase our general knowledge of protein adsorption as well as to open the way to the development of biointerfaces of interest for biomaterials science and tissue engineering. The work related to type I collagen adsorption performed in our laboratory over the past twenty years is reviewed. Substrate chemical nature and adsorption conditions (collagen concentration, adsorption duration) were shown to affect collagen adsorbed amount and supramolecular organization. Collagen assemblies were formed starting from the interface, and assembly was favored by hydrophobic substrates and high adsorbed amount. Substrates were designed to better control collagen adsorption and assembly. The spatial control of adsorption was ensured by chemically heterogeneous substrates, which also affected collagen assembly when domains with a dimension smaller than the length of the collagen molecule (i.e. 300nm) were prepared. Mixed polymer brushes were used to achieve a temporal control of adsorption: adsorption and desorption were reversibly triggered by changes of pH and ionic strength. Layer-by-layer assembly of collagen in a nanoporous template was used to elaborate collagen-based nanotubes, which were further deposited on ITO glass substrates by electrophoretic deposition. Finally, the evaluation of cell behavior on the created biointerfaces showed that the control of collagen organization can be successfully used to alter cell behavior.