Initial Cell Adhesion on Well-Defined Surface by Polymer Brush Layers with Varying Chemical Structures

To understand cellular responses at the interface between biological system and artificial materials, we considered several surface properties of the materials. Controlled surface properties were achieved for preparation of well-defined polymer brush substrates with varying chemical structures, which were prepared by surface-initiated atom transfer polymerization. The substrates were covered with hydrophilic polymer brush layers with anionic groups, cationic groups, and zwitterionic groups as well as nonionic hydroxyl groups. In addition, surface covered with hydrophobic fluoroalkyl groups was prepared. Initial cell adhesion was examined using human cervical adenocarcinoma epithelial cell line, as a model cell, and the cell adhesion onto the polymer brush substrates was evaluated related with cell adhesive protein adsorption. The number and morphology of adherent cells were clearly dependent on the surface ζ-potentials of polymer brush substrates. In contrast, no significant correlation was observed with respect to the hydrophilic/hydrophobic nature of the substrate, which was evaluated by static air contact angles at the surface in water. The number of adherent cells on the substrate increased with the absolute value of the surface ζ-potentials, and the cells did not adhere onto the substrate with zero surface ζ-potential, that is the polymer brush substrate with zwitterionic groups. The amount of protein adsorbed onto the substrates influenced cell adhesion, as did the surface ζ-potentials of the substrates. Therefore, we concluded that the initial cell adhesion is correlated with the surface ζ-potential on the substrate with polymer brush structures. The surface ζ-potential will be a good parameter for designing a cell adhesion-resistance substrate to prepare temporary or single-use biomedical devices.