title: Fullerol in human lens and retinal pigment epithelial cells: time domain fluorescence spectroscopy and imaging.
abstract: Fullerol is a fullerene derivative that is extensively hydroxylated [nano-C(60)(OH)(24)] and this makes it water-soluble. These fullerene derivatives have shown promise as drug carriers that bypass ocular barriers but fullerols are also potentially phototoxic to human lens and retinal tissues. Fluorescence imaging is a powerful and non-invasive means of probing nanoparticles in biological systems. However, fullerol nanoparticles have a very low level of fluorescence and have not as yet been imaged in vitro and in vivo. Using specialized measurements including time-correlated single photon counting (TCSPC), fullerol fluorescence was determined in aqueous solutions and detected in both human lens and retinal pigment epithelial cells. Time-resolved fluorescence of fullerol (5-200 μM) was characterized in aqueous environment, where the fluorescence decay is best fitted with three lifetimes (3 ns, 0.7-0.9 ns and 0.2 ns). Time-resolved microspectrofluorimetry and time-gated fluorescence imaging were performed on both human lens and retinal pigment epithelial cells incubated with increasing fullerol doses (5-500 μM and 5-50 μM, respectively). Upon increasing concentration, we observe some shortening of the lifetimes, a reduction in the relative amplitude of the shortest-living component and a corresponding increase in the weight of the intermediate-living species. Time-gated imaging of fullerol fluorescence provided information on its intracellular distribution that correlates with progressive cell damage. Therefore time-gated imaging may potentially be used as a means to investigate fullerol distribution and toxicity in the human lens and retina in vivo.
authors.affiliation: Dipartimento di Fisica, Politecnico di Milano, Milan, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Taroni
authors.forename: Cosimo
authors.initials: C
authors.lastname: D'Andrea
authors.forename: Gianluca
authors.initials: G
authors.lastname: Valentini
authors.forename: Rinaldo
authors.initials: R
authors.lastname: Cubeddu
authors.forename: Dan-Ning
authors.initials: DN
authors.lastname: Hu
authors.forename: Joan E
authors.initials: JE
authors.lastname: Roberts
mesh_terms: D004847:Epithelial Cells / Q000187:drug effects* / Q000528:radiation effects; D037741:Fullerenes / Q000737:chemistry* / Q000633:toxicity; D006801:Humans; D007908:Lens, Crystalline / Q000187:drug effects* / Q000528:radiation effects; D008027:Light; D055213:Retinal Pigment Epithelium / Q000166:cytology / Q000187:drug effects* / Q000528:radiation effects; D013050:Spectrometry, Fluorescence; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D037741:Fullerenes; C408042:fullerol C60(OH)24