Preparation and cell culture behavior of self-assembled monolayers composed of chitohexaose and chitosan hexamer

Chitohexaose and chitosan hexamer were site-selectively modified at each reducing end with thiosemicarbazide, followed by self-assembly chemisorption of the S-derivatives on a gold substrate via S-Au bonding. Quartz crystal microbalance analysis and X-ray photoelectron spectroscopy suggested successful formation of self-assembled monolayers (SAMs) consisting of chitin and chitosan with sugar densities 0.39 and 0.35 chains nm^-2, respectively. As-prepared SAMs were very hydrophilic (with water contact angles 12-13°) and flat at the nanometer scale (RMS ≈ 1.7 nm). Mouse fibroblasts (NIH-3T3) preferentially adhered to both SAMs, while fewer cells were attached to the more hydrophobic, intact gold substrate. The fixed carbohydrates induced good proliferation of NIH-3T3 cells, while surface treatment with free sugars had almost no positive effects. This architectural design of water-soluble oligosaccharide-SAMs is expected to provide a new approach for functional development of carbohydrate-decorated biointerfaces.