Cells adhesion/detachment control onto temperature-responsive glass coverslips modified with ultra thin poly(N-isopropylacrylamide) layer and its application of cell detachment process observed by TIRF microscopy

Poly(N-isopropylacrylamide) (PIPAAm) was covalently grafted on glass coverslips (PIPAAm-CSs) by electron beam irradiation. Thickness and amount of the grafted polymer amount were increased with the initial monomer concentration. PIPAAm-CSs with thicker and larger amount of the grafted polymer exhibited more hydrophilic surfaces. When the monomer concentration was 5 wt%, the grafted polymer density was 0.84 mug/cm², and cells adhered, spread on the surface at 37degC, but detached at 20degC. In contrast, when the monomer concentration was 35 wt%, the polymer density was 1.28 mug/cm², and the surfaces were cell repellent even at 37degC. These results showed a remarkable contrast to those with temperature-responsive polymer-grafted tissue culture polystyrene dishes, since various types of cells showed temperature-dependent cell adhesion/detachment when the grafted density was around 2 mug/cm² on these surfaces. We discuss the possible molecular mechanisms underlying this discrepancy. Furthermore, we applied PIPAAm-CS surfaces to observation of cell detachment process by using total internal reflectance fluorescence (TIRF) microscopy.