Surface modification of silica glass by CHF3 plasma treatment and carbon negative-ion implantation for cell pattern adhesion

We have investigated a method for the patterning of cell adhesion on a silica glass by using two-steps of surface modification processes of CHF3 plasma treatment and negative-ion pattern implantation. For the first step, exposure of CHF3 plasma to silica glass (SG) was used to obtain hydrophobic surface, leading to eliminate cell-adhesion property. After treatment with RF power of 20 W and exposure time of 120 s, the hydrophobicity was occurred from the increase in contact angle of SG from 43° to 88° and its reason based on XPS analysis was due to formations of C―F, C―F2, and C―F3 bonds, so-called fluorocarbonated bonds. Culture of mesenchymal stem cells (MSC) and rat adrenal pheochromocytoma cells (PC12h) showed the degradation of cell adhesion property on the plasma-treated SG surface. For the second step, carbon negative-ion implantation into the hydrophobic fluorocarbonated-SG surface was used to pattern the hydrophilic region, leading to enhance cell adhesion property. The contact angle of C-modified surface decreased to 76° at conditions of 15 keV and 1 × 1015 ions/cm2. XPS showed that the hydrophilicity was due to reduction of C―Fx bonds and formation of C―O and C═O bonds. After 3 days culture of MSC and PC12h on the C-implanted surface of the plasma-treated SG, a fairly good adhesion patterning of both cells was obtained on the ion-implanted regions.

Research Highlights
► We proposed a method for the patterning of cell adhesion on a silica glass.
► The glass was firstly exposed by CHF3 plasma to have hydrophobic surface due to C-F bonds.
► It was secondary implanted with carbon negative ions through a pattern mask.
► The implanted area loses C-F bonds to have hydrophilicity.
► Mesenchymal stem cells cultured on it showed a pattern adhesion along the implanted area.