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: 5.33). 07/2008; 42(11):4175-80. DOI: 10.1021/es702172w
Source: PubMed


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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Available from: Jerome Labille, Mar 16, 2015
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    • "The fullerenes are seen as potential PDT agents as they possess some favorable characteristics, which render them well suited as a photosensitizer [7]. Pristine C 60 is highly insoluble in water and biological media and, thus, forms nanoaggregates, which makes it poorly photoactive [8]. However, when fullerenes are functionalized with hydrophilic or amphiphilic functional groups, they become much more water soluble and can behave as PS [9]. "
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    ABSTRACT: The research interests of the Hamblin laboratory are broadly centered on the use of different kinds of light to treat many different diseases. Photodynamic therapy (PDT) uses the combination of dyes with visible light to produce reactive oxygen species and kill bacteria, cancer cells and destroy unwanted tissue. Likewise UV light is also good at killing especially pathogens. By contrast red or near-infrared light can have the opposite effect, to act to preserve tissue from dying and can stimulate healing and regeneration. In all these applications nanotechnology is having an ever-growing impact. In PDT, self-assembled nano-drug carriers (micelles, liposomes etc) play a great role in solubilizing the photosensitizers, metal nanoparticles can carry out plasmon resonance enhancement and fullerenes can act as photosensitizers themselves. In the realm of healing, single walled carbon nanotubes can be electrofocused to produce nano-electonic biomedical devices and nanomaterials will play a great role in restorative dentistry.
    Full-text · Article · Jan 2015
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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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    ABSTRACT: The fullerene C(60), due to the physicochemical properties of its spherical cage-like molecule build exclusively from carbon atoms, is able to both scavenge and generate reactive oxygen species. While this unique dual property could be exploited in biomedicine, the low water solubility of C(60) hampers the investigation of its behavior in biological systems. The C(60) can be brought into water by solvent extraction, by complexation with surfactants/polymers, or by long-term stirring, yielding pristine (unmodified) fullerene suspensions. On the other hand, a modification of the C(60) core by the attachment of various functional groups results in the formation of water-soluble fullerene derivatives. Assessment of toxicity associated with C(60) preparations is of pivotal importance for their biomedical application as cytoprotective (antioxidant), cytotoxic (anticancer), or drug delivery agents. Moreover, the widespread industrial utilization of fullerenes may also have implications for human health. However, the alterations in physicochemical properties imposed by the utilization of different methods for C(60) solubilization profoundly influence toxicological effects of fullerene preparations, thus making the analysis of their potential therapeutic and environmental toxicity difficult. This review provides a comprehensive evaluation of the in vitro and in vivo toxicity of fullerenes, focusing on the comparison between pristine and derivatized C(60) preparations and the mechanisms of their toxicity to mammalian cells and tissues.
    Full-text · Article · May 2012 · Archives of Toxicology
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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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    ABSTRACT: Numerous commercial products incorporate novel engineered nanomaterials such as gold, silica, zinc oxide, and fullerenes in complex matrices such as polymer composites, creams, and textiles. Analytical methods for detecting nanomaterials in complex matrices are not well developed. Moreover, nanomaterial content and properties of these commercial products are typically unknown and protected for proprietary reasons. This study had two primary aims: detection of C-60 within commercial face creams to establish a baseline concentration in these products (the first time this has been performed) and detection of residual C-60 reactivity remaining in the products aged in water under various light conditions with a view toward environmental exposure assessment. To achieve these aims, three commercial creams advertised as containing the fullerene nanomaterials were investigated using a range of analytical techniques. Among the detection methods tested, only extraction followed by high-performance liquid chromatography was able to detect fullerenes in these products. The measured quantities of C-60 in these creams represented <0.005% (w/w) with an unknown yield because total amounts added to the creams were unknown. Production of reactive oxygen species from these face creams was measured after aging them in water as well as exposing them to solar spectrum illumination or ultraviolet light, or storage in the dark. Singlet oxygen generated in the products after 48 h of aging was correlated with the amounts of C-60 extracted from preaged samples, indicating residual photochemical reactivity and pointing toward the long-term impacts of utilizing these materials in commercial products.
    Preview · Article · Sep 2010 · Environmental Engineering Science
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