Ls55b spectrofluorometer

The structural organization of bacterial membranes was analyzed by the fluorescence anisotropy values of the DPH and TMA-DPH probes. The number of S. aureus cells was photometrically standardized. Cells (cell suspension OD₆₀₀ = 0.01 in 10 mM PBS pH 7.4) were incubated with DPH or TMA-DPH at a final concentration of 1 µM for 15 min in the dark at 37 °C. After that, various concentrations of flavonoids (2.5–50 µM) were added to the bacterial cell suspension, and the cells were incubated for 45 min at 37 °C. The values for fluorescence anisotropy of the probes incorporated in the membranes were measured in the absence and in the presence of flavonoids using a Perkin-Elmer LS 55B spectrofluorometer (Perkin-Elmer, Pontyclun, UK).

Absorption measurements were recorded with a Lambda 35 spectrometer (Perkin Elmer, USA) and fluorescence measurements were conducted with LS55B spectrofluorometer (PerkinElmer, USA) equipped with polarizers, thermostated cuvette compartments and magnetic stirring for polarization experiments. Fluorescence quantum yield was measured as was previously described (λ_ex: 416 nm; λ_em: 652 nm) [40 (link)].

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)].