Preparation And Application Of Poly(dopamine)-based Thermoresponsive Surface Via SI-ATRP

Tailoring thermoresponsive polymer brush on solid surface is a powerful means of realizing non-enzymatic harvest of mammalian cells. Surface-initiated atom transfer radical polymerization (SI-ATRP) has been most extensively used to produce functional polymer surfaces. Compared to other polymerization techniques, the reaction of SI-ATRP is moderate and high activity. The key step of SI-ATRP is introducing high-density initiative groups on the solid surface. Poly(dopamine) coating provides a new method of the introduction of ATRP initiator groups on the surface without material restricted.We developed stepwise surface reactions to graft poly(N-isopropylacrylamide)(PNIPAAm) brush on solid surface. Solid surface (silicon wafer and glass) was coated with poly(dopamine), and then bromoalkyl group was introduced, followed by polymerization of NIPAAm monomer via SI-ATRP. The succesful stepwise reactions were spectroscopically evidenced by ATR-FTIR. AFM results of increasing in surface roughness and change in film thickness also validated the surface reactions. By varying temperature, we observed a reversible thermoresponse of the PNIPAAm-grafted surface. The PNIPAAm-grafted surface via our method was compatible with HepG2cells adhesion and growth at37℃. As the temperature dropped to15℃, HepG2cells easily detached without further treatment. Overall, the PNIPAAm-grafted surface via our method is suitable for non-enzymatic cell harvest. We also designed a new type of solid-liquid phase SI-ATRP reaction device to improve the preparation method of planar substrate. In addition, we studied the effect of PNIPAAm grafting to the spherical substrate.