Browsing by Author "Phounsavath, Sophia"

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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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    Gold nanoparticles and radiofrequency in experimental models for hepatocellular carcinoma
    (Elsevier, 2014) Raoof, Mustafa; Corr, Stuart J.; Zhu, Cihui; Cisneros, Brandon T.; Kaluarachchi, Warna D.; Phounsavath, Sophia; Wilson, Lon J.; Curley, Steven A.; Richard E. Smalley Institute for Nanoscale Science & Technology
    Hepatocellular carcinoma (HCC) is one of the most lethal and chemo-refractory cancers, clearly, alternative treatment strategies are needed. We utilized 10 nm gold nanoparticles as a scaffold to synthesize nanoconjugates bearing a targeting antibody (cetuximab, C225) and gemcitabine. Loading efficiency of gemcitabine on the gold nanoconjugates was 30%. Targeted gold nanoconjugates in combination with RF were selectively cytotoxic to EGFR expressing Hep3B and SNU449 cells when compared to isotype particles with/without RF (P < 0.05). In animal experiments, targeted gold nanoconjugates halted the growth of subcutaneous Hep3B xenografts in combination with RF exposure (P < 0.05). These xenografts also demonstrated increased apoptosis, necrosis and decreased proliferation compared to controls. Normal tissues were unharmed. We have demonstrated that non-invasive RF-induced hyperthermia when combined with targeted delivery of gemcitabine is more effective and safe at dosages ~ 275-fold lower than the current clinically-delivered systemic dose of gemcitabine.
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    RF heating of ultra-short single-walled carbon nanotubes and gadonanotubes for non-invasive cancer hyperthermia
    (2014-01-30) Phounsavath, Sophia; Wilson, Lon J.; Marti, Angel A.; Grande-Allen, K. Jane; Curley, Steven A.
    An emerging field of nanoparticle-mediated cancer therapy is based on the interaction of nanoparticles with radiofrequency (RF) energy to induce hyperthermia or thermal cytotoxicity within cancer cells. In this work, the heating properties of ultra-short single-walled carbon nanotubes (US-tubes) and gadonanotubes (GNTs) were assessed in an external radiofrequency field (900 W, 13.56 MHz). Surfactant (Pluronic F-108) suspensions of US-tubes (carbon-based nanocapsules that are 20-80 nm in length and 1.4 nm in diameter) and GNTs (US-tubes loaded internally with Gd3+ ions) heated in a concentration dependent manner when the RF field was applied. The observed bulk heating of the sample suspensions have been attributed to the nanomaterial itself and not the background surfactant solution. The efficacy of these remotely triggered heating agents to produce thermal cytotoxicity was then investigated in vitro in three different hepatocellular cancer cell lines (Hep3B, HepG2, and Snu449). In all cases, cancer cells that were treated with either US-tubes or GNTs in conjunction with RF had lower viabilities than those treated with RF alone. The ability of GNTs to induce thermal cytotoxicity in vivo was then investigated using subcutaneous tumor models in nude mice. Histopathological analysis of treated tumors demonstrated more pronounced and widespread cell damage in tumors treated with GNTs and RF than in the control tumors. It is anticipated that these results will aid in the future development of nanoparticle-mediated cancer therapy by hyperthermia.