Nanofabrication for micropatterned cell arrays by combining electron beam-irradiated polymer grafting and localized laser ablation

Most methods reported for cell‐surface patterning are generally based on photolithography and use of silicon or glass substrates with processing analogous to semiconductor manufacturing. Herein, we report a novel method to prepare patterned plastic surfaces to achieve cell arrays by combining homogeneous polymer grafting by electron beam irradiation and localized laser ablation of the grafted polymer. Poly(N‐isopropylacrylamide) (PIPAAm) was covalently grafted to surfaces of tissue culture‐grade polystyrene dishes. Subsequent ultraviolet ArF excimer laser exposure to limited square areas (sides of 30 or 50 μm) produced patterned ablative photodecomposition of only the surface region (∼100‐nm depth). Three‐dimensional surface profiles showed that these ablated surfaces were as smooth and flat as the original tissue culture‐grade polystyrene surfaces. Time‐of‐flight secondary ion mass spectrometry analysis revealed that the ablated domains exposed basal polystyrene and were surrounded with PIPAAm‐grafted chemistry. Before cell seeding, fibronectin was adsorbed selectively onto ablated domains at 20°C, a condition in which the non‐ablated grafted PIPAAm matrix remains highly hydrated. Hepatocytes seeded specifically adhered onto the ablated domains adsorbed with fibronectin. Because PIPAAm inhibits cell adhesion and migration even at 37°C when the grafted density is >3 μg/cm2, all the cells were confined within the ablated domains. A 100‐cell domain array was achieved by this method. This surface modification technique can be utilized for fabrication of cell‐based biosensors as well as tissue‐engineered constructs. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 1065–1071, 2003