Abstract

The interaction of meso-tetrakis(p-sulfonatophenyl)porphyrin (TPPS) with bovine serum albumin (BSA) in neutral solution (pH 7.4) has been studied by means of absorption, steady-state fluorescence and time-resolved fluorescence spectroscopy. The formation of TPPS–BSA complex was monitored by spectroscopic characteristic changes in Soret band absorption and fluorescence emission of TPPS. Applying the time-correlated single-photon counting (TCSPC) method, BSA–TPPS interaction was also investigated by the fluorescence lifetime of tryptophan residues in BSA. The results demonstrate that deep UV laser-based fluorescence lifetime microscopy is useful for sensitive identification of protein interaction using intrinsic fluorescence.