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

Abstract

Abstract: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 m) produced patterned ablative photodecomposition of only the surface region (ϳ100-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 PIPAAmgrafted 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 Ͼ3 g/cm 2 , 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 cellbased biosensors as well as tissue-engineered constructs.

Tissue Engineering Based on Cell Sheet Technology

“…We have also successfully prepared micro patterned surfaces with grafting polyacrylamide (PAAm), a hydrophilic polymer, followed by UV ArF excimer laser ablation. Hepatocytes [77] and endothelial cells [78] adhere only to the ablated domains adsorbed with fibronectin at 37°C. Furthermore, we have also prepared patterned dual thermoresponsive surfaces for co-culture of heterotypic cells and then recovered as an intact cell sheet.…”

Thermoresponsive platforms for tissue engineering and regenerative medicine

“…However, some PNIPAAm coated surfaces were not suitable for the formation of tissue monolayers as they inhibit cell attachment at temperatures above LCST. 41,42 …”

Laser microstructuring of photomodified fluorinated ethylene propylene surface for confined growth of Chinese hamster ovary cells and single cell isolation

“…Methods like UV 21 or plasma treatment 28,29 can result in a drastic increase in the wettability and also of the compatibility for cell adhesion. After 30 min of UV treatment in NH 3 [ Figure 1(a)], the measured contact angle drops to 64 .…”