Fullerene nanoparticles (nCx; x = 60 or 70) with a monodisperse size and morphology are obtained through guest exchange of a γ-cyclodextrin (γ-CD) complex.

Stepwise growth of fullerene nanoparticles (nC ; x=60 or 70) was performed through guest exchange of a γ-cyclodextrin (γ-CD) complex. Fullerenes bicapped by γ-CD were mixed with presynthesized nC in the presence of poly(ethylene glycol) (PEG) in water. Fullerenes expelled from the γ-CD hosts by PEG were piled on the original nC , resulting in growth of nC . This process could be repeated and the size of nC increased according to the number of growth steps. The growth of fullerene nanoparticles was confirmed by UV/Vis absorption spectroscopy, dynamic light scattering measurements, and TEM observations. The stepwise growth method also enabled the preparation of C /C core/shell fullerene nanoparticles, which had the ability to photogenerate active oxygen, O .

Hybridization of fullerenes with hydrophilic materials is important for fullerene applications in the fields of biology and medicine. Here, we demonstrate transfer of fullerenes from the cavity of g-cyclodextrin to hydrogel substrates. Fullerene C 60 or C 70 transfers to a gelatin gel substrate at 80 8C or room temperature, respectively. UltravioletÀvisible absorption spectroscopy and transmission electron microscopy of the fullerene-containing gel substrates reveal that formation of fullerene nanoparticles is the key process for smooth transfer of fullerene into an aqueous environment. This method is applicable for transfer of fullerenes into various types of hydrogel substrates, such as agarose and N-isopropylacrylamide gels.

Hybrid nanoparticles comprising fullerene and porphyrin are formed via guest exchange reaction of cyclodextrin complexes. The hybrid nanoparticles exhibit singlet oxygen generation ability under photoirradiation.