Fullerene singlet oxygen generation

Prat F, Stackow R, Bernstein R et al. (1999) Triplet-state properties and singlet oxygen generation in a homologous series of functionalized fullerene derivatives. J Phys Chem. 103 7230-7235. 

Of all the fullerene forms, the nearly spherical properties of C o have attracted the greatest attention, especially in the field of bioconjugation. In addition to its physical properties, C o fullerenes have unique photo-optical and electro-chemical properties, which make them useful as carriers for biomedical research applications. For instance, upon exposure to light C o will generate singlet oxygen, which can be used in vivo to cleave biological molecules, particularly DNA and RNA. Studies indicate that irradiation of Cgo in solution can be used to destroy virus contamination (Kasermann and Kempf, 1997). Solutions of Buckminsterfullerene are a deep purple color, whereas other sizes of fullerenes display a variety of other colors. 

Sera N, Tokiwa H, Miyata N (1996) Mutagenicity of the fullerene C60-generated singlet oxygen dependent formation of lipid peroxides. Carcinogenesis 17 2163-2169. 

So, fullerenes C60 and their derivatives may be potential damaging agents of biologic systems upon PDT, because upon irradiation C60 molecule is able to generate singlet oxygen, selectively penetrate tumor cells, and be accumulated there and could be easily removed from biologic medium. 

Danilov OB, Belousova IM, Mak AA, Belousov VP, Grenishin AS, Kiselev VM, Kris ko AV, Ponomarev AN, Sosnov EN (2003) Generation of singlet oxygen with the use of optically excited fullerenes and fullerene-like nanoparticles. Optics and Spectroscopy 95 833-842. 

Photo-oxidation requires the use of photocatalysts, which generate singlet oxygen under UV radiation or exposure to sunlight. Examples of photocatalysts include the dyes Rose Bengal, Methylene Blue, and fullerenes in solvents such as water, methanol, and acetonitrile [66-68]. The oxidation products in turn are insoluble in fuel and can be separated with the catalyst phase. 

Hybrid structures of dendrimers with other entities have been synthesized for their collective properties. The most common is PEGylation of dendrimers (Kojima et al. 2010) to increase their circulation in the blood and to avoid immune clearance. Lipids have also been attached on the surface of PAMAM dendrimers to reduce toxicity and increase cellular uptake (Jevprasesphant et al. 2003). More interesting architectures have been created such as attachment of C60 fullerene balls (Jensen et al. 2005) on the surface of PAMAM dendrimers that act as nanoreactors by the generation of singlet oxygen species. In another instance, dendrimer-based micelles have also been prepared for anticancer therapy (Jang et al. 2005). Table 85.2 lists some of these hybrid structures. 

Juha, L., Hamplova, V., Kodymovd, J., and Spalek, A., Reacitvity of fullerenes with chemicaUy generated singlet oxygen,/. Chem. Soc., Chem. Commun., 1177,1994. 

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