Decacationic [70]Fullerene Approach for Efficient Photokilling of Infectious Bacteria and Cancer Cells.

Photodynamic inactivation of pathogenic bacteria and cancer cells by novel water-soluble decacationic fullerene monoadducts, C60[>M(C3N6+C3)2] and C70[>M(C3N6+C3)2], were investigated. In the presence of a high number of electron-donating iodide anions as parts of quaternary ammonium salts in the arm region, we found that C70[>M(C3N6+C3)2] produced more highly reactive HO• radical than C60[>M(C3N6+C3)2], in addition to singlet oxygen (1O2). This finding offers an explanation of the preferential killing of Gram-positive and Gram-negative bacteria by C60[>M(C3N6+C3)2] and C70[>M(C3N6+C3)2], respectively. The hypothesis is that 1O2 can diffuse more easily into porous cell walls of Gram-positive bacteria to reach sensitive sites, while the less permeable Gram-negative bacterial cell wall needs the more reactive HO• to cause real damage.