Functional peptide-polyurethane conjugates with extended circulatory half-lives

Peptides containing the RGD sequence were covalently attached to an isocyanate-containing polyurethane prepolymer and the biological properties of the complexes were evaluated. For the pentapeptide H2N-Tyr-Arg-Gly-Asp-Ser-OH (single-letter code, YRGDS), polymer conjugation lead to an increased half-life in the blood circulation of mice to > 10 h. The effect of covalent attachment of polymer on biological activity was examined in a related peptide, H2N-Gly-Arg-Gly-Asp-Ser-Pro-Ala-Cys- OH (GRGDSPAC). Inhibition of B16-F10 melanoma cell attachment and spreading on plates coated with fibronectin by an RGD-containing peptide and polymer-conjugated GRGDSPAC was observed to occur at similar concentrations. We conclude that the conjugation of peptides containing the Arg-Gly-Asp motif to this polymer resolves previous problems of their rapid loss from the circulation, while still allowing retention of full biological inhibitory activity.