A PROBABILISTIC APPROACH TO MEASURE THE STRENGTH OF BONE CELL-ADHESION TO CHEMICALLY-MODIFIED SURFACES

Patterned surfaces with alternating regions of amino silanes [N-(2-ami noethyl)-3-aminopropyl-trimethoxysilane (EDS)] and alkyl silanes [dime thyldichlorosilane (DMS)] have been used to alter the kinetics of spat ial distribution of cells in vitro. In particular, we have previously observed the preferential spatial distribution of bone cells on the ED S regions of EDS/DMS patterned surfaces (10). In this study, we examin ed whether the mechanism of spatial distribution of cells on the EDS r egions was adhesion mediated. Homogeneous layers of EDS and DMS were i mmobilized on quartz substrates and characterized by contact angle, X- ray photoelectron spectroscopy, and spectroscopic ellipsometry. The st rength of bone cell attachment to the modified substrates was examined using a radial flow apparatus, within either 20 min or 2 hr of cell i ncubation in the presence of serum. A Weibull distribution was chosen to characterize the strength of cell-substratum adhesion. Within 20 mi n of cell exposure, the strength of adhesion was significantly larger on EDS and clean surfaces, compared with DMS surfaces (p < 0.001). Wit hin 2 hr of cell incubation, there was no statistical difference betwe en the strength of cell adhesion to EDS, DMS, and clean surfaces. The results of this study suggest that the surface chemistry mediates adhe sion-based spatial cell arrangement through a layer of adsorbed serum proteins.