This paper investigates the ability to modify the surface of silicon wafers for selective cell adhesion and the efficacy of solid phase transfections on the modified surface. Silicon surfaces are first modified by plasma polymerization of allylamine (ALAPP) and subsequent grafting of a protein-resistant layer of poly(ethylene oxide) (PEO) on the plasma polymer surface. Spatially controlled excimer ablation was then used to pattern the graft-copolymer surface for selective cell adhesion. X-ray photoelectron spectroscopy and contact angle measurements confirmed the creation of 2D patterns with different surface chemistry. Cell culture experiments with HEK 293 cells showed that cell attachment is limited to the ablated areas. Furthermore, cells could be transformed with plasmid DNA containing the gene for green fluorescent protein. Therefore, the biochip platform described in this paper, has the potential to be developed into a high-density array for analyzing gene products produced from a matrix of living cells.