Temperature-responsive glass coverslips with an ultrathin poly(N-isopropylacrylamide) layer

A temperature-responsive cross-linked polymer gel was covalently grafted onto glass coverslips by electron beam irradiation. The grafted thickness and amount of polymer as well as the surface wettability increased with the initial monomer concentration. When the monomer concentration was 5 wt.%, the grafted polymer density was 0.84 μg cm−2, and cells adhered and spread on the surface at 37 °C, but detached at 20 °C. In contrast, when the monomer concentration was 35 wt.%, the polymer density was 1.28 μg cm−2, and the surfaces were cell repellent even at 37 °C. These results show a remarkable contrast to those obtained from 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 μg cm−2 on these surfaces. We discuss the possible molecular mechanisms underlying this discrepancy.