According to an aspect of the present invention, medical devices are provided, which contain (a) a substrate and (b) a polymeric region disposed over the substrate which contains at least one block copolymer. The block copolymer, in turn, contains at least two polymer blocks which phase separate into two or more immiscible phase domains within the polymeric region. Moreover, a bioactive species is covalently attached to at least one of the polymer blocks. By attaching the bioactive species selectively to at least one polymer block, self-assembled clusters of the bioactive species are created as the blocks phase separate into immiscible phase domains.
