A composition includes at least one biologically active agent covalently attached to a first polymerizing molecule that is adapted to undergo a free radical polymerization. The first polymerizing molecule retains the ability to undergo free radical polymerization after attachment of the bioactive agent thereto. The first polymerizing molecule is preferably biocompatible. The polymerizing molecule can, for example. be dihydroxyphenyl-L-alanine (DOPA) or tyrosine. The composition can also include a second component synthesized by reacting at least one core molecule having a plurality of reactive hydrogen groups with at least one multi-isocyanate functional molecule to create a conjugate including terminal isocyanate groups. The conjugate molecule is reacted with a second polymerizing molecule that is adapted to undergo a free radical polymerization. The second polymerizing molecule includes a reactive hydrogen to react with the isocyanate groups of the conjugate. The second polymerizing molecule retains the ability to undergo the free radical polymerization after reaction with the conjugate. In several embodiments, the first polymerizing molecule and the second polymerizing molecule are the same and dihydroxyphenyl-L-alanine (DOPA) or tyrosine.