Structural and dynamic aspects of electron transfer in proteins — highly organized natural nanostructures

Nanoparticles of water-soluble dyads based on amino acid fullerene C60 derivatives and pyropheophorbide: Synthesis, photophysical properties, and photodynamic activity

Synthesis, spectral properties, and photodynamic activity of water-soluble amino acid fullerene C₆₀ derivatives (AFD) and four original AFD-PPa dyads, obtained by covalent addition of dye pyropheophorbide (PPa) to AFD, were studied. In aqueous solution, these AFD-PPa dyads form nanoassociates as a result of self-assembly. In this case, a significant change in the absorption spectra and strong quenching of the dye fluorescence in the structure of the dyads were observed. A comparison of superoxide or singlet oxygen generation efficiency of the studied compounds in an aqueous solution showed the photodynamic mechanism switching from type II (singlet oxygen generation of the native dye) to I type (superoxide generation of dyads). All dyads have pronounced phototoxicity on cells Hela with IC₅₀ 9.2 µM, 9.2 µM, 12.2 µM for dyads Val-C₆₀-PPa, Ala-C₆₀-PPa and Pro-C₆₀-PPa, respectively. Such facilitation of type I photodynamic mechanism could be perspective against hypoxic tumors.