Abstract

Mostafa Rezaei-Tavirani^¹, Saeid Heidari K^¹ and Esmaeil Biazar^²*

The UV radiation method is a suitable method for grafting processes. Poly-N-isopropylacrylamide was successfully grafted onto a polystyrene surface with benzophenone initiator under UV radiation. In this study, grafted polystyrene was exposed to microwave plasma treatment with oxygen gas. The ATR-FTIR analysis showed the existence of the graft poly-N-isopropylacrylamide (PNIPAAm) on the surface by this method also attenuated total reflection Fourier transform infrared spectra investigations of irradiated sample indicated clearly the presence of functional groups. Atomic force microscopic images of samples irradiated with active gas and grafted sample indicated nanometric surface topography. Sample irradiated with oxygen plasma showed more roughness compared with those un-modified samples. Surface roughness increased with increasing duration of exposure, which could be due to reduction of the contact angle of samples irradiated with oxygen plasma. Contact angle analysis showed reduction in samples irradiated with plasma. Samples irradiated with oxygen plasma showed a lower contact angle compared with those un-modified samples. Thermo-responsive polymers were grafted to dishes covalently, which allowed epithelial cells to attach and proliferate at 37°C; the cells were also detached spontaneously without using enzymes when the temperature dropped below 4°C.  Also MTT analysis showed a good viability of cells on the grafted samples especially for modified sample with plasma. Such a characteristic proved that this type of grafted material had the potentiality as a biomaterial for cell sheet engineering.

Grafting; Surface modification; PNIPAAm; UV Radiation; Oxygen plasma

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