Solubilization of the photosensitizers TPCS2a and TPPS 2a in aqueous media evaluated by time-resolved fluorescence analysis

The pH-dependent aggregation of the novel photosensitizer TPCS2a is investigated at low concentration (c=10-6 M) in aqueous media by means of time-correlated single-photon counting, and compared to that of the chemically related photosensitizer TPPS2a. The efficacy of selected solubilizers, i.e., various nonionic Pluronic block copolymers and the nonionic surfactant Tween 80, in inhibiting aggregation of the two photosensitizers is evaluated, which is important for the further formulation of TPCS2a.