Interactions of Water-Insoluble Tetraphenylporphyrins with Micelles Probed by UV−Visible and NMR Spectroscopy,

Abstract

For developing clinically useful porphyrin drugs, it is essential to characterize porphyrin−membrane interactions and to determine the factors that modulate such interactions. To this end, four uniquely p-phenyl-substituted tetraphenylporphyrins were synthesized. These water-insoluble, unsymmetrically substituted porphyrins were allowed to diffuse into aqueous micellar solutions formed by the surfactants tetradecyltrimethylammonium bromide (TTAB), sodium dodecyl sulfate (SDS), and poly(ethylene glycol)-p-t-octylphenol (TX-100). The abilities of the porphyrins to localize in these micelles were determined by UV−vis and NMR spectroscopy. The data show that the NO2−phenyl-substituted porphyrin did not diffuse into any of the micellar solutions. The COO--substituted porphyrin was solubilized in cationic TTAB and in nonionic TX-100 micellar solutions under neutral and basic conditions. The NH3+-substituted porphyrin incorporated in anionic SDS micelles at pH = 2 and in TX-100 micelles at pH 2 and 7. These resu...