Funct. Mater. 2020; 27 (1): 12-17.


Effect of chlorin e6 molecular form on the induced singlet oxygen luminescence

M.Y.Losytskyy, R.A.Kharchenko, Y.I.Harahuts, P.A.Virych, N.V.Kutsevol, V.M.Yashchuk

T. Shevchenko National University of Kyiv, 64/13 Volodymyrs'ka Str., 01601 Kyiv, Ukraine


Chlorin e6 is a known photosensitizer used in photodynamic therapy of cancer as a component of existing formulations and in development of novel ones. Upon the increase of pH, chlorin e6 is known to undergo a molecular transition (considered to be the molecule deprotonation) at about pH 6.1-6.4, and the effects of this transition on singlet oxygen generation by chlorin e6 should be considered. Here we have studied the effect of solvent (Tris-HCl buffer (pH 7.2) vs distilled water) and of the presence of dextran-polyacrylamide and dextran-polyacrylamide-co-polyacrylic acid graft polymers in distilled water on the luminescence of the singlet oxygen generated by chlorin e6. Luminescence intensity of singlet oxygen generated in the solution of chlorin e6 in distilled water (where chlorin e6 is mostly in its protonated form) was shown to be much higher than in Tris-HCl buffer where chlorin e6 is non-protonated. At the same time, the presence of dextran-polyacrylamide and dextran-polyacrylamide-co-polyacrylic acid graft polymers in distilled water results in the transition of chlorin e6 to its non-protonated form. This is accompanied by a decrease in singlet oxygen luminescence intensity. Based on these observations, we suggest that the efficiency of singlet oxygen generation by chlorin e6 (upon excitation at the wavelength of its Soret band) is higher for protonated form of chlorin e6 as compared to non-protonated one.

photodynamic therapy, chlorin e<sub>6</sub>, graft polymers, singlet oxygen luminescence.
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