Directed collagen patterning on gold-coated silicon substrates via micro-contact printing

The ability to create biologically functional systems from non-biological materials has importance in the arena of tissue engineering and medical device implantation. Directing the immobilization of proteins to specified regions on a substrate has attracted a lot of attention as one potential approach. Functionalization of the surface of gold-coated silicon wafers was accomplished by micro-contact printing a hydrophilic (or hydrophobic) self-assembled monolayer (SAM) atop the gold coating using poly(dimethylsiloxane) (PDMS) stamps. Afterwards, the substrate was soaked in a solution of hydrophobic (or hydrophilic) surfactant molecules which filled in the un-stamped area. The intention was to use carbodiimide coupling to attach fluorescently labeled collagen to COOH-terminated (hydrophilic) regions of the substrate. However, even in the presence of the reagents for this reaction, the collagen preferred to assemble on the hydrophobic regions. The results suggest that micro-contact printing may provide a simple mechanism for patterning collagen onto surfaces simply using selective adsorption. This might be useful for examining directed cell interactions, or to enhance the biocompatibility of inorganic materials used as substrates in tissue engineering or devices that are to be implanted into the body.