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Carbon-covered magnetic nanomaterials and their application for the thermolysis of cancer cells.

Xu Y, Mahmood M, Fejleh A, Li Z, Watanabe F, Trigwell S, Little RB, Kunets VP, Dervishi E, Biris AR, Salamo GJ, Biris AS - Int J Nanomedicine (2010)

Bottom Line: X-ray diffraction and X-ray photoelectron spectroscopy analysis revealed that the cores inside the carbon shells of these NPs were preserved in their metallic states.Low RF radiation of 350 kHz induced localized heating of the magnetic NPs, which triggered cell death.Apoptosis inducement was found to be dependent on the RF irradiation time and NP concentration.

View Article: PubMed Central - PubMed

Affiliation: Nanotechnology Center and Applied Science Department, University of Arkansas at Little Rock, Little Rock, AR, USA. yxxu@ualr.edu; asbiris@ualr.edu

ABSTRACT
Three types of graphitic shelled-magnetic core (Fe, Fe/Co, and Co) nanoparticles (named as C-Fe, C-Fe/Co, and C-Co NPs) were synthesized by radio frequency-catalytic chemical vapor deposition (RF-cCVD). X-ray diffraction and X-ray photoelectron spectroscopy analysis revealed that the cores inside the carbon shells of these NPs were preserved in their metallic states. Fluorescence microscopy images indicated effective penetrations of the NPs through the cellular membranes of cultured cancer HeLa cells, both inside the cytoplasm and the nucleus. Low RF radiation of 350 kHz induced localized heating of the magnetic NPs, which triggered cell death. Apoptosis inducement was found to be dependent on the RF irradiation time and NP concentration. It was showed that the Fe-C NPs had a much higher ability of killing the cancer cells (over 99%) compared with the other types of NPs (C-Co or C-Fe/Co), even at a very low concentration of 0.83 microg/mL. The localized heating of NPs inside the cancer cells comes from the hysteresis heating and resistive heating through eddy currents generated under the RF radiation. The RF thermal ablation properties of the magnetic NPs were correlated with the analysis provided by a superconducting quantum interference device (SQUID).

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A) Normal HeLa cells without incubation of magnetic NPs; B) After 24 hours incubation time, the magnetic C-Co NPs were found to aggregate around and further penetrate into the nucleus of HeLa cells. C) The images took from the Olympus confocal microscopy indicating the membrane blebbing of HeLa cells incubated with magnetic C-Fe NPs after 350 kHz RF heating for two minutes. Confocal microscopy images indicating the extensive live and dead cells after being incubated with the C-Co NPs D) C-Fe/Co NPs E), and C-Fe NPs F) after exposure to RF radiation for two minutes. The cells were stained in order to distinguish between the live (green for acridine orange) and the dead cells (orange for ethidium bromide).
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f4-ijn-5-167: A) Normal HeLa cells without incubation of magnetic NPs; B) After 24 hours incubation time, the magnetic C-Co NPs were found to aggregate around and further penetrate into the nucleus of HeLa cells. C) The images took from the Olympus confocal microscopy indicating the membrane blebbing of HeLa cells incubated with magnetic C-Fe NPs after 350 kHz RF heating for two minutes. Confocal microscopy images indicating the extensive live and dead cells after being incubated with the C-Co NPs D) C-Fe/Co NPs E), and C-Fe NPs F) after exposure to RF radiation for two minutes. The cells were stained in order to distinguish between the live (green for acridine orange) and the dead cells (orange for ethidium bromide).

Mentions: Temperature changes of the NP powder upon exposure to RF radiation were studied in order to investigate the heating effects generated by the three different magnetic NPs. Five minutes of RF heating was considered sufficient in order to highlight the heating rates and the temperature differences between the three types of NPs. The high sensitivity thermal analysis indicated that the RF induced temperatures, as well as their heating rates, rose and were found to be dependent mostly upon the mass of the NPs used for the measurements. The C-Fe NPs were shown to be the best hyperthermia agents for killing the cancer cells since they were found to reach temperatures higher than the C-Fe/Co and C-Co NPs under identical RF exposure conditions (Figure 3c). Based on these experimental results and given the significant mass difference between the NPs present inside the cells and the cells themselves, the death of the cells is not expected to occur as a result of the bulk heating of the entire cell structures, but rather due to the localized damages of the cell such as nuclear membrane destruction, DNA fragmentation, and thermal denaturation of proteins (which happen at temperatures higher than 55 °C). As shown in Figure 4, after the NPs were taken up into the HeLa cell cytoplasm they were able to cross the various intercellular membranes and reach the nucleus.10 Due to the localized RF heating provided by the NPs, the cells were found to go through an apoptotic process, and subsequent cellular decomposition (one of the signs of the apoptotic process: the cell membrane blebbing) was observed as a result (Figure 4c). Compared to different NPs, as shown in Figures 4d–f, the C-Fe NPs revealed the highest efficiency for inducing cell death when compared to the C-Fe/Co NPs and C-Co NPs after two minutes of RF exposure. The disintegration of localized cellular environments such as nucleus, nuclear membranes, and DNA were believed to be the effective response resulting from RF-heat inducement into the NPs.


Carbon-covered magnetic nanomaterials and their application for the thermolysis of cancer cells.

Xu Y, Mahmood M, Fejleh A, Li Z, Watanabe F, Trigwell S, Little RB, Kunets VP, Dervishi E, Biris AR, Salamo GJ, Biris AS - Int J Nanomedicine (2010)

A) Normal HeLa cells without incubation of magnetic NPs; B) After 24 hours incubation time, the magnetic C-Co NPs were found to aggregate around and further penetrate into the nucleus of HeLa cells. C) The images took from the Olympus confocal microscopy indicating the membrane blebbing of HeLa cells incubated with magnetic C-Fe NPs after 350 kHz RF heating for two minutes. Confocal microscopy images indicating the extensive live and dead cells after being incubated with the C-Co NPs D) C-Fe/Co NPs E), and C-Fe NPs F) after exposure to RF radiation for two minutes. The cells were stained in order to distinguish between the live (green for acridine orange) and the dead cells (orange for ethidium bromide).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2865011&req=5

f4-ijn-5-167: A) Normal HeLa cells without incubation of magnetic NPs; B) After 24 hours incubation time, the magnetic C-Co NPs were found to aggregate around and further penetrate into the nucleus of HeLa cells. C) The images took from the Olympus confocal microscopy indicating the membrane blebbing of HeLa cells incubated with magnetic C-Fe NPs after 350 kHz RF heating for two minutes. Confocal microscopy images indicating the extensive live and dead cells after being incubated with the C-Co NPs D) C-Fe/Co NPs E), and C-Fe NPs F) after exposure to RF radiation for two minutes. The cells were stained in order to distinguish between the live (green for acridine orange) and the dead cells (orange for ethidium bromide).
Mentions: Temperature changes of the NP powder upon exposure to RF radiation were studied in order to investigate the heating effects generated by the three different magnetic NPs. Five minutes of RF heating was considered sufficient in order to highlight the heating rates and the temperature differences between the three types of NPs. The high sensitivity thermal analysis indicated that the RF induced temperatures, as well as their heating rates, rose and were found to be dependent mostly upon the mass of the NPs used for the measurements. The C-Fe NPs were shown to be the best hyperthermia agents for killing the cancer cells since they were found to reach temperatures higher than the C-Fe/Co and C-Co NPs under identical RF exposure conditions (Figure 3c). Based on these experimental results and given the significant mass difference between the NPs present inside the cells and the cells themselves, the death of the cells is not expected to occur as a result of the bulk heating of the entire cell structures, but rather due to the localized damages of the cell such as nuclear membrane destruction, DNA fragmentation, and thermal denaturation of proteins (which happen at temperatures higher than 55 °C). As shown in Figure 4, after the NPs were taken up into the HeLa cell cytoplasm they were able to cross the various intercellular membranes and reach the nucleus.10 Due to the localized RF heating provided by the NPs, the cells were found to go through an apoptotic process, and subsequent cellular decomposition (one of the signs of the apoptotic process: the cell membrane blebbing) was observed as a result (Figure 4c). Compared to different NPs, as shown in Figures 4d–f, the C-Fe NPs revealed the highest efficiency for inducing cell death when compared to the C-Fe/Co NPs and C-Co NPs after two minutes of RF exposure. The disintegration of localized cellular environments such as nucleus, nuclear membranes, and DNA were believed to be the effective response resulting from RF-heat inducement into the NPs.

Bottom Line: X-ray diffraction and X-ray photoelectron spectroscopy analysis revealed that the cores inside the carbon shells of these NPs were preserved in their metallic states.Low RF radiation of 350 kHz induced localized heating of the magnetic NPs, which triggered cell death.Apoptosis inducement was found to be dependent on the RF irradiation time and NP concentration.

View Article: PubMed Central - PubMed

Affiliation: Nanotechnology Center and Applied Science Department, University of Arkansas at Little Rock, Little Rock, AR, USA. yxxu@ualr.edu; asbiris@ualr.edu

ABSTRACT
Three types of graphitic shelled-magnetic core (Fe, Fe/Co, and Co) nanoparticles (named as C-Fe, C-Fe/Co, and C-Co NPs) were synthesized by radio frequency-catalytic chemical vapor deposition (RF-cCVD). X-ray diffraction and X-ray photoelectron spectroscopy analysis revealed that the cores inside the carbon shells of these NPs were preserved in their metallic states. Fluorescence microscopy images indicated effective penetrations of the NPs through the cellular membranes of cultured cancer HeLa cells, both inside the cytoplasm and the nucleus. Low RF radiation of 350 kHz induced localized heating of the magnetic NPs, which triggered cell death. Apoptosis inducement was found to be dependent on the RF irradiation time and NP concentration. It was showed that the Fe-C NPs had a much higher ability of killing the cancer cells (over 99%) compared with the other types of NPs (C-Co or C-Fe/Co), even at a very low concentration of 0.83 microg/mL. The localized heating of NPs inside the cancer cells comes from the hysteresis heating and resistive heating through eddy currents generated under the RF radiation. The RF thermal ablation properties of the magnetic NPs were correlated with the analysis provided by a superconducting quantum interference device (SQUID).

Show MeSH
Related in: MedlinePlus