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 demonstrat e an example of how a biocompatible polymer can be easily patterned upon an other polymer substrate, creating a surface with two spatially different pr operties. A poly(dimethylsiloxane) mold allowed the patterning of a negativ e replica of an E-PROM microchip, forming a spatially defined pattern with a period of approximately 1 mum. The amphiphilic biocompatible polymer, pol y(lactic acid)-poly(ethylene glycol) (PLA-PEG), was used as the "ink" in or der to block off areas of a hydrophobic, polystyrene (PS) substrate. This c reated a surface with two properties: 2-3 mum strips of PLA-PEG polymer, wh ich resists protein adsorption, divided by micrometer strips of PS. The abi lity of the patterning technique to provide a true heterogeneous surface wa s analyzed using atomic force microscopy, while fluorescence microscopy pro vided a high-contrast method by which to trace the position of specific mol ecules. 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-a ssembled monolayers.