Development of a cell patterning technique using poly(ethylene glycol) disilane

A simple technique for controlling cell adhesion on glass substrates by surface modification using a commercially available poly(ethylene glycol) (PEG) disilane, which can bind directly to glass in a single step, in combination with photolithographic micropatterning, was developed, characterized, and evaluated for patterning of HepG2 hepatoma cells and 3T3 fibroblasts. The optimal concentration of PEG-disilane for surface modification was 5 mM, and patterning of strongly adherent cells such as HepG2 required the chelation of divalent metal cations in order to inhibit nonspecific binding and cell aggregation. Whereas the average thickness of the PEG-disilane layer was 18 +/- 3.5 nm, the perimeters of patterned areas of exposed glass exhibited ridges of average height 857 +/- 50 nm, which may have aided in constraining cell spreading and migration. Although unpatterned PEG-treated substrates were hydrophilic (contact angle 46 +/- 1degrees), micropatterned surfaces behaved as if they were somewhat hydrophobic (contact angle similar to90degrees), necessitating special protocols for preventing deleterious dewetting of cells. For optimized protocols, the probability of adhesion of HepG2 cells to a patterned area of exposed glass was almost 15 times higher than the probability of adhesion to a PEG-treated background region of equal area. Our technique is useful for short- to intermediate-term patterning of cell or tissue morphology, e.g., for investigation of the effects of cell-cell interactions or cell geometry.