Dynamics and efficiency of the photosensitized singlet oxygen formation by chlorin e 6: The effects of the solution pH and polyvinylpyrrolidone

The effects of the solution pH and polyvinylpyrrolidone on the dynamics and efficiency of the formation of singlet oxygen 1O2 in buffer media (pH 6.3–8.5) photosensitized by chlorin e 6 are studied. It is demonstrated that the quantum yield of the 1O2 formation photosensitized by chlorin e 6 decreases with decreasing solution pH due to the aggregation of photosensitizer molecules. Polyvinylpyrrolidone facilitates the disaggregation of chlorin e 6, thus increasing its photosensitizing ability. For a complex of chlorin e 6 with this polymer, the luminescence kinetics of singlet oxygen is inverted, which should be taken into account in the determination of the lifetime of 1O2 in real biological systems.