Surface Modification of SiO2 Microchannels with Biocompatible Polymer Using Supercritical Carbon Dioxide

The surface of 500-mm-long microchannels in SiO 2 microchips was modified using supercritical CO 2 (scCO 2 ) and a biocompatible polymer was coated on it to confer biocompatibility to the SiO 2 surface. In this method, the SiO 2 surface of a microchannel was coated with poly(ethylene glycol monomethacrylate) (PEGMA) as the biocompatible polymer using allyltriethoxysilane (ATES) as the anchor material in scCO 2 as the reactive medium. Results were compared with those using the conventional wet method. The surface of a microchannel could not be modified by the wet method owing to the surface tension and viscosity of the liquid, but it was modified uniformly by the scCO 2 method probably owing to the near-zero surface tension, low viscosity, and high diffusivity of scCO 2 . The effect of the surface modification by the scCO 2 method to prevent the adsorption of protein was as high as that of the modification by the wet method. Modified microchips can be used in biochemical and medical analyses.