Modification of stent surfaces to impart functionality

A coated substrate comprising:

• a. a substrate having a surface,
• b. a cationic polymer layer adjacent the surface of the substrate,
• wherein the cationic polymer layer comprises at least one residue of a first compound having the structure:
• wherein R1 is hydrogen or alkyl;
• wherein R2, R3a, R3b, R4a, R4b, R5a, R5b, R6a, and R6b are, independently, hydrogen, hydroxyl, alkyl, aryl, alkoxy, carboxyl, ester, amino, or amide, with the provisos that at least one of R2, R3a, R3b, R4a, R4b, R5a, R5b, R6a, and R6b is amino and that at least one of R2, R3a, R3b, R4a, R4b, R5a, R5b, R6a, and R6b is hydroxyl or alkoxy;
• and
• c. an anionic polymer layer adjacent the cationic layer,
• wherein the anionic polymer layer comprises at least one residue of a compound having the structure:
• wherein R12, R13, and R14 are, independently, hydrogen, alkyl, aryl, carboxyl, or ester;
• and
• wherein R15, R16, R17, R18, and R19 are, independently, hydrogen, alkyl, aryl, alkoxy, amino, amide, carboxyl, or ester, with the proviso that at least one of R15, R16, R17, R18, and R19 is SO3R11, wherein R11 is hydrogen or alkyl.