A substrate having an active agent immobilized on a surface thereof, the substrate comprising a layer of a primer compound on the substrate surface, wherein the layer of the primer compound includes a compound including a trihydroxyphenyl group coupled thereto selected from the group consisting of gallic acid, phloroglucinol carboxylic acid, gallamide, 5-methyl-benzene-1,2,3-triol, 3,4,5-trihydroxybenzaldehyde, 2,3,4-trihydroxybenzaldehyde, gallacetophenone, 3,4,5-trihydroxybenzamide, 2,3,4-trihydroxybenzoic acid, 5-hydroxydopamine hydrochloride, methyl gallate, derivatives thereof, salts of the foregoing, and combinations thereof, and wherein the compound comprising the trihydroxyphenyl group includes an active agent coupled thereto.