A simple method for biocompatible polymer based spatially controlled adsorption of blood plasma proteins to a surface

Using the soft lithographic technique, microcontact printing, we demonstrate an example of how a biocompatible polymer can be easily patterned upon another polymer substrate, creating a surface with two spatially different properties. A poly(dimethylsiloxane) mold allowed the patterning of a negative replica of an E-PROM microchip, forming a spatially defined pattern with a period of approximately 1 mum. The amphiphilic biocompatible polymer, poly(lactic acid)-poly(ethylene glycol) (PLA-PEG), was used as the "ink" in order to block off areas of a hydrophobic, polystyrene (PS) substrate. This created a surface with two properties: 2-3 mum strips of PLA-PEG polymer, which resists protein adsorption, divided by micrometer strips of PS. The ability of the patterning technique to provide a true heterogeneous surface was analyzed using atomic force microscopy, while fluorescence microscopy provided a high-contrast method by which to trace the position of specific molecules. We believe this technique to be an elegant demonstration of how the properties of polymers can be exploited in order to arrange molecules at a surface, avoiding the more difficult use of gold, self-assembly, or self-assembled monolayers.