Bone cell–materials interaction on Si microchannels with bioinert coatings

Bone implant life is dependent upon integration of biomaterial surfaces with local osteoblasts. This investigation studied the effects of various microchannel parameters and surface chemistry on immortalized osteoblast precursor cell (OPC1) adhesion. Cell–materials interactions were observed within channels of varying length, width, tortuosity, convergence, divergence and chemistry. Si wafers were used to create four distinct 1 cm2 designs of varying channel dimensions. After anisotropic chemical etching to a depth of 120 μm, wafers were sputter coated with gold and titanium; and on another surface SiO2 was grown to vary the surface chemistry of these microchannels. OPC1 cells were seeded in the central cavity of each chip before incubation in tissue culture plates. On days 5, 11 and 16, samples were taken out, fixed and processed for microscopic analysis. Samples were visually characterized, qualitatively scored and analyzed. Channel walls did not contain OPC1 migration, but showed locally interrupted adhesion. Scores for channels of floor widths as narrow as 350 μm were significantly reduced. No statistically significant preference was detected for gold, titanium or SiO2 surfaces. Bands of OPC1 cells appeared to align with nearby channels, suggesting that cell morphology may be controlled by topography of the design to improve osseointegration.