Article

Mechanisms of photochemistry and reactive oxygen production by fullerene suspensions in water

Department of Civil and Environmental Engineering, Duke University, Durham, North Carolina 27708-0287, USA.
Environmental Science and Technology (Impact Factor: 5.48). 07/2008; 42(11):4175-80. DOI: 10.1021/es702172w
Source: PubMed

ABSTRACT Buckminsterfullerene (C60) is a known photosensitizer that produces reactive oxygen species (ROS) in the presence of light; however, its properties in aqueous environments are still not well understood or modeled. In this study, production of both singlet oxygen and superoxide by UV photosensitization of colloidal aggregates of C60 in water was measured by two distinct methods: electron paramagnetic resonance (EPR) with a spin trapping compound, and spectrophotometric detection of the reduced form of the tetrazolium compound XTT. Both singlet oxygen and superoxide were generated by fullerol suspensions while neither was detected in the aqu/nC60 suspensions. A mechanistic framework for photosensitization that takes into account differences in C60 aggregate structure in water is proposed to explain these results. While theory developed for single molecules suggests that alterations to the C60 cage should reduce the quantum yield for the triplet state and associated ROS production, the failure to detect ROS production by aqu/nC60 is explained in part by a more dense aggregate structure compared with the hydroxylated C60.

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    • "); O–H out-of-plane bending in carbon nanotubes (Baudot et al. 2010) b C 60 (OH) n (Bogdanovic et al. 2004); C–O bond in C 60 (OH) n (Isakovic et al. 2006) c C 60 (OH) n (Krishna et al. 2008) d C–O epoxide (Tianbao et al. 1999); THF-nC 60 (Lee et al. 2010) e O–H in C 60 (OH) n (Alves et al. 2006); C–O stretching in C 60 (OH) n (Krishna et al. 2008); C–O in son-nC 60 without solvent, and C 60 (OH) n (Hwang and Li 2010); C–OH in-plane bending or O=C–O– in irradiated C 60 (Hou and Jafvert 2009b) f C 60 (OH) n (Bogdanovic et al. 2004); C–O bond in C 60 (OH) n (Semenov et al. 2011) g C–OH stretching in C 60 ozopolymer (Cataldo and Heymann 2006); C–O bond in C 60 (OH) n (Husebo et al. 2004) h C 60 (Haufler et al. 1990; Bethune et al. 1991); C 60 O (Creegan et al. 1992); precipitate from THF-nC 60 (Wei et al. 1997); C–O stretching in C 60 ozopolymer (Cataldo and Heymann 2006); C 60 , THF-nC 60 , and C 60 (OH) n (Isakovic et al. 2006; Harhaji et al. 2006); THF-nC 60 (Fortner et al. 2007); C–C bond in son-nC 60 no solvent (Labille et al. 2009); C 60 (Hou and Jafvert 2009b); C 60 in toluene (Bae et al. 2011); son-nC 60 with toluene (Wang et al. 2012; An and Jin 2011) i THF-nC 60 (Lee et al. 2010); O–H out-of-plane bending in carbon nanotubes (Baudot et al. 2010) j C–OH in-plane bending in C 60 ozopolymer (Cataldo and Heymann 2006); O–H bending in C 60 (OH) n (Zhang et al. 2003); water molecules in C 60 in toluene (Bae et al. 2011); son-nC 60 with toluene (Wang et al. 2012; An and Jin 2011) k C 60 (Hou and Jafvert 2009b; Haufler et al. 1990; Bethune et al. 1991); C 60 O (Creegan et al. 1992); precipitate from THF-nC 60 (Wei et al. 1997); C 60 and O–H bond in C 60 (OH) n (Alves et al. 2006); THF-nC 60 (Fortner et al. 2007); C–C in son-nC 60 without solvent (Hwang and Li 2010); hemiketal in son-nC 60 with toluene (An and Jin 2011); C 60 in toluene (Bae et al. 2011); son-nC 60 with toluene (Wang et al. 2012) l C 60 (Semenov et al. 2011; Bethune et al. 1991); C–OH bending in C 60 (OH) n (Krishna et al. 2008); -O–H bending in C 60 (OH) n (Chao et al. 2011) m C 60 (Bethune et al. 1991); C–H bending in C 60 (Kamaras et al. 1993); C–H asymmetrical bending in C 60 precipitated from C 60 hydrosol (Andrievsky et al. 2002); C–C or C–H scissoring in C 60 (OH) n (Hotze et al. 2008); son-nC 60 with toluene (Wang et al. 2012) n C 60 (Bethune et al. 1991); clathrated CO 2 in C 60 (Kamaras et al. 1993); C–O bond in C 60 (Hou and Jafvert 2009b) o Amorphous carbon structure in C 60 (Sreseli et al. 2005) p Hemiketal in C 60 (OH) n (Krishna et al. 2008; Xing et al. 2004) q O–H covalent bond in THF-nC 60 (Isakovic et al. 2006) r Hemiketal in C 60 (OH) n (Xing et al. 2004) s C–O in C 60 (Hou and Jafvert 2009b) t C–H asymmetrical bending in C 60 precipitated from C 60 hydrosol (Andrievsky et al. 2002); C–H asymmetrical stretching in THF-nC 60 (Fang et al. 2007); THF-nC 60 (Lee et al. 2007); C–H stretching in C 60 (OH) n (Vileno et al. 2010); C–H bond in C 60 (Bae et al. 2011) u O–H bond in C 60 (OH) n (Krishna et al. 2008); O–H stretching in C 60 (OH) n (An and Jin 2011) moieties or determining formation pathway. FTIR spectroscopy has been used to identify surface groups found in association with fullerene species (Ibrahim and El-Haes 2005; Troshin et al. 2006; Chao et al. 2011; Wang et al. 2012), but has not been used reliably to quantify these groups. "
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    ABSTRACT: The present study was carried out to evaluate transformation kinetics of derivatized fullerene species by simulating natural aquatic processes, which will help elucidate biological effects of water-stirred nano-C60 (aqu-nC60). Physicochemical analyses of aqu-nC60 included molecular and agglomerate-scale characterization, surface charge analysis through examination of electrophoretic mobility, and chemical composition analysis using spectroscopy. Detailed analysis of aqu-nC60 transformation over a 28-day stirring period in both light and dark conditions indicated aqu-nC60 agglomerate concentrations can be estimated as a time-function using a predictor model (R 2 > 0.99). Number-weighted agglomerate size did not differ significantly over the 28-day stirring period regardless of photocondition, although size distributions were more uniform as stirring time increased. The total number of surface groups identified through XPS indicated increased derivatization as a function of time with additions assigned to mono-oxygenated carbon moieties while the number of di-oxygenated moieties declined. Earlier-phase stirring (t ≤ 14 days) products were shown to contain epoxide surface groups, which were absent in later-phase (t > 14 days) suspensions, suggesting specific pathways to derivatization with preferential mono-oxygenated states. Filter residue, a by-product of the aqu-nC60 synthesis process, demonstrated high hydrophobicity and FTIR spectra similar to underivatized material, suggesting synthesis process inefficiencies.
    Journal of Nanoparticle Research 10/2013; 15(11). DOI:10.1007/s11051-013-2069-4 · 2.28 Impact Factor
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    • "The degree to which the fullerene core is functionalized appears to affect the tendency of C 60 to form aggregates. Accordingly, monofunctionalized molecules tend to aggregate more than polyfunctionalized fullerenes which exhibit greater stability (Hotze et al. 2008). It is generally believed that the derivatization of the fullerene cage significantly decreases the toxic properties of functionalized fullerenes. "
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    Archives of Toxicology 05/2012; 86(12). DOI:10.1007/s00204-012-0859-6 · 5.08 Impact Factor
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    • "UV, ul- traviolet. FULLERENE DETECTION AND ROS PRODUCTION IN COSMETIC PRODUCTS 801 and Wiesner, 2005; Hotze et al., 2008; Chae et al., 2009a "
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