Synthesis, Surface and Cell-Adhesion Properties of Polyurethanes Containing Covalently Grafted RGD-Peptides

In an attempt to improve endothelial cell adhesion and growth on a polyurethane copolymer, cell adhesive RGD-containing peptides were grafted to the polymer backbone. Two peptide grafting reaction schemes, including one-step and two-step approaches, were developed. Amino acid analysis confirmed that the two-step approach had a higher peptide coupling efficiency. The two-step reaction scheme was utilized to prepare GRGDSY, GRGDVY and GRGESY (inactive control) peptide grafted polyurethanes with two different peptide densities (100 and 250 μmol/g polymer). Dynamic contact angle measurements indicated that the surfaces of the peptide grafted polyurethanes were more hydrophilic than the starting and carboxylated versions of the precursor polyurethane. In-vitro endothelial cell adhesion experiments showed that, without the presence of serum in culture medium, the GRGDSY- and GRGDVY-grafted polyurethanes dramatically enhanced cell attachment and spreading. Increasing the peptide density from 100 to 250 μmol/g polymer for the GRGDSYand GRGDVY-grafted polyurethanes resulted in an increase in cell attachment. With approximately the same peptide density (100 or 250 μmol/g polymer), the GRGDVY-grafted polymers supported more adherent cells than the GRGDSY-grafted polymers. Similar trends were observed in the in-vitro endothelial cell growth studies using culture medium containing serum and endothelial cell growth supplement. These RGD-peptide grafted polyurethanes may be useful in providing an easily prepared cell-adhesive substrate for various implantable devices and hybrid organs.