Adhesion, proliferation, and detachment of cells on poly(N-isopropyl acrylamide) brushes tethered on polystyrene using surface-initiated atom transfer radical polymerization

Abstract

The preparation of thermo-responsive cell culture dishes through grafting poly(N-isopropyl acrylamide) (PNIPAAm) brushes is described. The effect of different treatments, including ultraviolet-ozone (UVO) and ozone exposure on hydroxyl functionalization of the tissue culture polystyrene (TCPS) dishes, was investigated. The surface of TCPS dishes was activated by UVO irradiation, and the synthesized initiator was immobilized on the surface. PNIPAAm brushes were yielded by surface-initiated atom transfer radical polymerization (SI-ATRP). Surface composition and properties of grafted PNIPAAm on polystyrene surface were studied by X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), energy-dispersive X-ray (EDX) spectroscopy, and water contact angle (WCA). The results show that PNIPAAm brushes were successfully grafted on the TCPS, and the WCA of the surface was raised from 33 to 64° by increasing the temperature from 20 to 40 °C, which is suitable for cell sheet detachment. Different cell types, including MG, endothelial, and fibroblast cells, were cultured on the PNIPAAm-grafted TCPS. The cell culture results show that the attachment to the surface and proliferation were successfully carried out. The formed cell sheet was also detached by decreasing the temperature from 37 to 20 °C. Therefore, the grafted PNIPAAm brushes are useful for the preparation of cell sheets from different cell types.