Characterization of mTHPC-Loaded Liposomes

Absorption measurements were recorded with a Lambda 35 spectrometer (Perkin Elmer, USA) and fluorescence measurements were conducted with a LS55B spectrofluorometer (PerkinElmer, USA) equipped with polarizers, thermostated cuvette compartments, and magnetic stirring for polarization experiments. The concentrations of mTHPC in DL-DCLs and Foslip^® were estimated spectroscopically (λem = 652 nm) by dissolving nanoparticles in methanol. DL-DCLs were previously purified by minicolumn chromatography. Fluorescence quantum yield and photoinduced fluorescence quenching were measured as previously described (λ_ex: 416 nm; λ_em: 652 nm) [15 (link)]. The measurements of mTHPC fluorescence anisotropy were performed as described earlier (λ_ex: 430 nm; λ_em: 652 nm) [15 (link)]. EE of mTHPC in DCLs was measured spectroscopically (λ_em: 652 nm) immediately after extrusion and purification, as previously described [7 (link)].
The hydrodynamic diameter of NPs, polydispersity index, and Z-potential were determined using photon-correlated spectroscopy by a Zetasizer Nano ZS (Malvern Instruments, UK) as previously reported [7 (link)].