Surface modification for controlled studies of cell-ligand interactions

This work describes a method for coupling cell adhesion peptides to hydroph obic materials for the purpose of controlling surface peptide density while simultaneously preventing nonspecific protein adsorption. PEO/PPO/PEO trib lock copolymers (Pluronic(TM) F108) were equipped with terminal pyridyl dis ulfide functionalities and used to tether RGD containing peptides to polyst yrene (PS). The density of F108 on PS was 1.4 E5 +/- 2.12 E1 molecules/mu m (2). XPS and ToF SIMS indicated that the F108 coating was homogeneous and t hat the unmodified and activated F108 distributed evenly on PS. By mixing u nmodified F108 with PDS-activated F108 prior to adsorption, it was possible to vary peptide density between 0 and 8.7 E4 +/- 2.66 E3 peptides/mu m(2), while otherwise, maintaining consistent surface properties. GRGDSY grafted PS supported cell attachment, spreading, and development of cytoskeletal s tructure, all of which were found to increase with increasing peptide densi ty. Cell proliferation followed this same trend, however, maximal growth oc curred at a submaximal peptide density. Cell aspect ratio varied in a bipha sic manner with GRGDSY density. F108 coated PS and GRGESY grafted PS were i nert to cell adhesion. Cells released from GRGDSY grafted PS upon addition of either a reducing agent or free GRGDSY, which indicates that cell-substr ate interactions were mediated solely by the tethered peptides. (C) 1999 Pu blished by Elsevier Science Ltd. All rights reserved.