Arrangement of type IV collagen and laminin on substrates with controlled density of -OH groups.

Collagen IV (Col IV) and laminin (Lam) are the main structural components of the basement membrane where they form two overlapping polymeric networks. We studied the adsorption pattern of these proteins on five model surfaces with tailored density of -OH groups obtained by copolymerization of different ratios ethyl acrylate (EA) and hydroxyl EA (HEA): X(OH)=0, X(OH)=0.3, X(OH)=0.5, X(OH)=0.7, and X(OH)=1 (where X refers the ratio of HEA). Atomic force microscopy revealed substratum-specific adsorption patterns of Col IV and Lam, ranging from single molecules deposition on more hydrophilic substrata to the formation of complex networks on hydrophobic ones. Human umbilical endothelial cells were used to study the biological performance of adsorbed proteins, following the overall cell morphology, the quantities for cell adhesion and spreading, and the development of focal adhesion complexes and actin cytoskeleton. Surprisingly, two optima in the cellular interaction were observed-one on the most hydrophilic X(OH)=1 and other on the relatively hydrophobic X(OH)=0.3 substrate-valid for both Col IV and Lam. When the proteins were adsorbed consecutively, a hydrophobic shift to X(OH)=0 substratum was obtained. Collectively, these data suggest that varying with the density of -OH groups one can tailor the conformation and the functional activity of adsorbed basement membrane proteins.