Collagen I and III and their decorin modified surfaces studied by atomic force microscopy and the elucidation of their affinity toward positive apolipoprotein B-100 residue by quartz crystal microbalance.

Collagen, the major component of extracellular matrix (ECM) and the most abundant protein in the human body, is implicated in the development of atherosclerosis. Collagen types I and III were immobilized on fused-silica capillary to investigate their shape, size and structure by atomic force microscopy (AFM). For comparison, collagen was also immobilized on a mica surface. Our studies demonstrated that not only does the adsorption pattern on the substrate vary with the type of collagen, but also the substrate material plays an important role in the fibril formation process. Decorin, which promotes the binding of low-density lipoprotein (LDL) particles with collagen, was investigated for its effect on the fibrillogenesis. On both substrate materials, addition of decorin clearly reduced the fibril diameter of collagen surfaces. Moreover, a quartz crystal microbalance (QCM)-based biosensor approach was applied to clarify and evaluate the affinity of different collagen coatings immobilized on a silicon dioxide sensor chip toward apolipoprotein B-100, the major protein of LDL. The results confirmed the importance of collagen type and their fibrillogenesis on the binding of the positive residues of apolipoprotein B-100 on negatively charged collagen surfaces.