In this paper, we describe the development and characterization of a biochip platform for cell transfection assays. Silicon wafers were surface modified by plasma polymerization of allylamine plasma polymer (ALAPP) and grafting of a protein-resistant layer of poly(ethylene oxide) (PEO) on the plasma polymer surface. Excimer laser ablation was then used to pattern ALAPP-PEO coated samples for spatially controlled protein adsorption and subsequent cell attachment. X-ray photoelectron spectroscopy (XPS) was used to characterize the surface modifications before and after excimer laser ablation. Experiments confirmed the creation of a two-dimensionally controlled surface chemistry on the biochip. Cell culture experiments using human embryonic kidney (HEK 293) cells showed that cells attached exclusively to laser ablated areas. In addition, cells confined to ablated areas were successfully transfected with plasmid DNA containing the gene for green fluorescent protein (GFP). The cell transfection efficiencies of cells growing in a culture flask and cells confined on the biochip were determined to be 21 and 13%, respectively.
- Plasma polymerization