13th World Congress for Laser Dentistry

26-28, April 2012

Barcelona, Spain

Meeting Abstract

Sponsors: World Federation for Laser Dentistry

- Oral Presentation 53

TITLE: PDT with C84 fullerenes - Excitation wavelengths and photochemical mechanisms.

AUTHORS: Sperandio FF, Sharma SK, Wang M, Huang YY, Dai T, Sousa SCOM, Chiang LY, Hamblin MR.

Wellman Center for Photomedicine; Department of Dermatology - Harvard Medical School; Department of Oral Pathology - University of Sao Paulo

SOURCE: Med Oral Patol Oral Cir Bucal. 2012 May 1;17(Supplement1):S53.

* doi:10.4317/medoral.17643552

http://dx.doi.org/10.4317/medoral.17643552

Abstract

The fullerene molecule has shown great potential for a variety of applications in physics, chemistry, engineering and also biomedical purposes including photodynamic therapy (PDT). The absorption of visible light with consequent electron transfer and energy transfer processes leading to generation of reactive oxygen species mean fullerenes may be effective photosensitizers (PSs). For this study two C84 fullerene-based compounds were functionalized and gave rise to two distinct PSs, LC19 and LC20 having deca-cationic chains. Both compounds were chemically similar, only differing by the incorporation of an additional decatertiary amine chain as an additional source of electrons in LC20. PDT was performed in HeLa cells with UVA, blue, green, white and red light. Different killing curves were obtained for each wavelength used and the ratio between LC19 and LC20 was calculated to show an almost perfect linear correlation (R=0.988) with the wavelengths employed. Low concentrations of ascorbic acid stimulated higher generation of hydroxyl radicals only when LC20 was illuminated with UVA light. C84 fullerenes induced apoptosis of HeLa cancer cells and cell damage demonstrated by acridine orange and rhodamine 123 fluorescent probes. In conclusion the incorporation of a deca-tertiary amine chain in the chemical structure of the C84 fullerene gave more PDT killing by improving higher electron transfer when photo-stimulated with shorter wavelengths or in presence of ascorbate.