Complexes of Chlorin e6 with Pluronics and Polyvinylpyrrolidone: Structure and Photodynamic Activity in Cell Culture

• Published in: Photochemistry and photobiology 2014-01, Vol.90 (1), p.171-182
• Main Authors: Zhiyentayev, Timur M., Boltaev, Umed T., Solov'eva, Anna B., Aksenova, Nadezhda A., Glagolev, Nickolay N., Chernjak, Alexander V., Melik-Nubarov, Nickolay S.
• Format: Article
• Language: English
• Subjects: Animals; Cell culture; Cells, Cultured; Chlorine; Coordination Complexes - chemistry; Hydrophilic surfaces; Light therapy; Mice; Molecular Structure; Photobiology; Photochemistry; Photosensitizing Agents - chemistry; Poloxamer - chemistry; Polymers; Porphyrins - chemistry; Povidone - chemistry
• ISSN: 0031-8655; 1751-1097
• DOI: 10.1111/php.12181

Polymeric carriers are extensively used in photodynamic therapy (PDT) for increase of efficacy of photosensitizers. Here, we report the influence of nine Pluronic copolymers on phototoxicity of chlorin e6 (Ce6), in particular 5‐ to 7‐fold rise in the phototoxicity caused by hydrophilic Pluronics F127, F108, F68 and F87 and practically no influence on Ce6 of more hydrophobic polymers. The revealed value of 0.2 mg mL−1 of Pluronic F127 concentration sufficient for half‐of‐maximal increase of Ce6 photodynamic activity proved to be close to 0.16 mg mL−1 inherent in well‐documented carrier poly(N‐vinylpyrrolidone) (PVP). The dissociation constants of Ce6 complexes with Pluronic F127 and PVP that were estimated from UV spectra were 0.252 and 0.036 mg mL−1, respectively, indicating higher stability of Ce6 complex with PVP. According to the results of 1H‐NMR studies of Ce6 complexes, the porphyrin interacts not only with hydrophobic regions but also with hydrophilic sides of both polymers. Non‐covalent binding of Chlorin e6 to hydrophilic polymers results in 5–7‐fold enhancement of its phototoxicity in vitro.