The atmospheric pressure plasma treatment on plasma polymer thin films was investigated to control the immobilization of DNA alignment. The amine groups of aminopropyltriethoxysilane have been generally used for the fixation of DNA on the substrate. However, it is easily influenced by humidity, and so it is hard to control precisely the formation of the self-assembled monolayer. The plasma polymer thin films with the atmospheric pressure plasma treatment are expected to be hardly influenced by

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... umidity. Moreover, the densities of the amine groups are expected to be controlled by the treatment. In this work, organic and organic-inorganic hybrid plasma polymer thin films were formed on Si(100) by plasma enhanced chemical vapor deposition using methylcyclohexane and tetraethylorthosilane (TEOS), and the amine groups were formed on the surfaces by N 2 atmospheric pressure plasma treatment. Fourier-transform infrared absorption spectroscopy showed that the amine groups were increased with the treatment. The surface densities of the amine groups were obtained from averaged extinction coefficients of UV-visible absorption spectra. DNA fixation was successfully performed with a tilting method for aligning well stretched DNAs on the surfaces, through optimization of the surface condition in the treatment. #