Electrochemically controlled release of alpha,beta,gamma,delta-tetrakis(4-N-methylpyridyl)porphine from layer-by-layer thin films.

The release of alpha,beta,gamma,delta-tetrakis(4-N-methylpyridyl)porphyrin (TMPyP) from layer-by-layer assembled thin films composed of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) was electrochemically controlled. The release rate of TMPyP was enhanced when a positive electrode potential (+1.2 to +1.5 V) was applied to the glassy carbon electrode on which TMPyP-loaded PAH/PAA film was coated, while the effect of lower electrode potentials (0 to +1.0 V) was negligibly small. The effect of applied potential on the release rate was more significant at pH 7.4 than in the solutions of pH 8.0 and 9.0. The electrochemically enhanced release of TMPyP was rationalized based on local pH change in the vicinity of the electrode surface, which was induced by electrolysis of H(2)O.