Browsing by Author "Cheney, Matthew A."

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    Citrate-Capped Gold Nanoparticle Electrophoretic Heat Production in Response to a Time-Varying Radio-Frequency Electric Field
    (American Chemical Society, 2012) Corr, Stuart J.; Raoof, Mustafa; Mackeyev, Yuri; Phounsavath, Sophia; Cheney, Matthew A.; Cisneros, Brandon T.; Shur, Michael; Gozin, Michael; McNally, Patrick J.; Wilson, Lon J.; Curley, Steven A.; Smalley Institute for Nanoscale Science and Technology
    The evaluation of heat production from gold nanoparticles (AuNPs) irradiated with radio-frequency (RF) energy has been problematic due to Joule heating of their background ionic buffer suspensions. Insights into the physical heating mechanism of nanomaterials under RF excitations must be obtained if they are to have applications in fields such as nanoparticle-targeted hyperthermia for cancer therapy. By developing a purification protocol that allows for highly stable and concentrated solutions of citrate-capped AuNPs to be suspended in high-resistivity water, we show herein, for the first time, that heat production is only evident for AuNPs of diameters ≤10 nm, indicating a unique size-dependent heating behavior not previously observed. Heat production has also shown to be linearly dependent on both AuNP concentration and total surface area and was severely attenuated upon AuNP aggregation. These relationships have been further validated using permittivity analysis across a frequency range of 10 MHz–3 GHz as well as static conductivity measurements. Theoretical evaluations suggest that the heating mechanism can be modeled by the electrophoretic oscillation of charged AuNPs across finite length scales in response to a time-varying electric field. It is anticipated these results will assist future development of nanoparticle-assisted heat production by RF fields for applications such as targeted cancer hyperthermia.
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    Cytotoxicity and variant cellular internalization behavior of water-soluble sulfonated nanographene sheets in liver cancer cells
    (Springer, 2013) Corr, Stuart J.; Raoof, Mustafa; Cisneros, Brandon T.; Kuznetsov, Oleksandr; Massey, Katheryn; Kaluarachchi, Warna D.; Cheney, Matthew A.; Billups, Edward W.; Wilson, Lon J.; Curley, Steven A.; Richard E. Smalley Institute for Nanoscale Science and Technology
    Highly exfoliated sulfonated graphene sheets (SGSs), an alternative to graphene oxide and graphene derivatives, were synthesized, characterized, and applied to liver cancer cells in vitro. Cytotoxicity profiles were obtained using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, WST-1[2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, and lactate dehydrogenase release colorimetric assays. These particles were found to be non-toxic across the concentration range of 0.1 to 10 μg/ml. Internalization of SGSs was also studied by means of optical and electron microscopy. Although not conclusive, high-resolution transmission and scanning electron microscopy revealed variant internalization behaviors where some of the SGS became folded and compartmentalized into tight bundles within cellular organelles. The ability for liver cancer cells to internalize, fold, and compartmentalize graphene structures is a phenomenon not previously documented for graphene cell biology and should be further investigated.
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    Evidence for nuclear internalisation of biocompatible [60]fullerene1)
    (Walter de Gruyter GmbH, 2013) Huang, Feiran; Mackeyev, Yuri; Watson, Erin; Cheney, Matthew A.; Wilson, Lon J.; Suh, Junghae; Richard E. Smalley Institute for Nanoscale Science and Technology
    Many types of nanoparticles (NPs) have been shown to internalise within mammalian cells (1), but only a few have been observed to internalise within the cell nucleus-most likely due to the tightly-regulated nuclear membrane (2). Internalisation of NPs into the nucleus is desirable for several reasons, including their use as 1. transfection agents (3), 2. drug delivery platforms for drugs that act on DNA (4), and 3. hyperthermia-inducing agents for cancer therapy using non-invasive stimulation by radiofrequency irradiation (5), magnetic-field cycling (6), or photonic activation (7). For example, derivatised NPs, including protein-functionalised quantum dots (8) and peptide-functionalised gold NPs (9), have been shown to internalise into the nucleus. For underivatised NPs, single-walled carbon nanotubes (SWNTs), have been observed by direct transmission electron microscopy (TEM) imaging to also localise in the nucleus of human macrophage cells with dose-dependent cytotoxicity (10). Fullerene C60ﾠis another classic carbon-based NP, however it was not been shown to enter the cell nucleus until recently. In particular, a water soluble derivative of C60ﾠfluorescently labelled with a small molecule fluorophore was shown to enter cell nuclei through nuclear pore complexes in liver cancer cells (11). Here, we validate the nuclear internalisation ability of the C60derivative in several other cell types, further supporting the unique intracellular biodistribution property of this specific fullerene compound.