A polybifunctional reagent is provided having a polymeric backbone, one or more pendent latent reactive (preferably photoreactive) moieties, and two or more pendent bioactive groups. The reagent can be activated to form a bulk material or can be brought into contact with the surface of a previously formed biomaterial and activated to form a coating. The pendent bioactive groups function by promoting the attachment of specific molecules or cells to the bulk material or coated surface. Bioactive groups can include proteins, peptides, carbohydrates, nucleic acids and other molecules that are capable of binding noncovalently to specific and complimentary portions of molecules or cells.