MORPHOLOGY OF ADSORBED COLLAGEN LAYERS OBSERVED BY ATOMIC FORCE MICROSCOPY

The interaction between cells and biomaterials strongly depends on the assembled structure of collagen adsorption upon the solid surface. Due to its self-assembling property, Type I collagen may aggregate and form fibrils in vivo and in vitro. This study utilizes an atomic force microscope to investigate nanometer-scale organization of adsorbed Type I collagen layers on mica and on poly(methyl methacrylate) (PMMA). We have observed various film morphologies, depending on substrate hydrophobicity and the state of collagen solution used. On mica, the atomic force microscopy (AFM) study obtains dense felt-like structures of randomly distributed assemblies. Images of network-like assemblies composed of interwoven fibrils appear on PMMA. According to the above results, we believe that these assemblies are associated at the interface rather than aggregated in the solution. This work also investigates the adsorbed collagen structure on PMMA after collagen aggregation in solution, to realize the relation between adsorption and aggregation. Consequently, the result exhibits a dendritic fibrillar structure adsorbed on PMMA, following collagen molecule aggregation, to form a fibrillar structure in the solution. This result suggests that the adsorption of aggregates preformed in the solution is preferable to collagen molecules adsorption. This research created all assembled structures of adsorbed collagen layers in nanometer-scale thickness.