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Single-walled carbon nanotube interactions with HeLa cells.

Yehia HN, Draper RK, Mikoryak C, Walker EK, Bajaj P, Musselman IH, Daigrepont MC, Dieckmann GR, Pantano P - J Nanobiotechnology (2007)

Bottom Line: Transmission electron microscopy revealed SWNT-like material in intracellular vacuoles.The combined results indicate that under our sample preparation protocols and assay conditions, CoMoCAT DM-SWNT dispersions are not inherently cytotoxic to HeLa cells.We conclude with recommendations for improving the accuracy and comparability of carbon nanotube (CNT) cytotoxicity reports.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, The University of Texas at Dallas, Richardson, TX 75080, USA. pantano@utdallas.edu.

ABSTRACT
This work concerns exposing cultured human epithelial-like HeLa cells to single-walled carbon nanotubes (SWNTs) dispersed in cell culture media supplemented with serum. First, the as-received CoMoCAT SWNT-containing powder was characterized using scanning electron microscopy and thermal gravimetric analyses. Characterizations of the purified dispersions, termed DM-SWNTs, involved atomic force microscopy, inductively coupled plasma - mass spectrometry, and absorption and Raman spectroscopies. Confocal microRaman spectroscopy was used to demonstrate that DM-SWNTs were taken up by HeLa cells in a time- and temperature-dependent fashion. Transmission electron microscopy revealed SWNT-like material in intracellular vacuoles. The morphologies and growth rates of HeLa cells exposed to DM-SWNTs were statistically similar to control cells over the course of 4 d. Finally, flow cytometry was used to show that the fluorescence from MitoSOXtrade mark Red, a selective indicator of superoxide in mitochondria, was statistically similar in both control cells and cells incubated in DM-SWNTs. The combined results indicate that under our sample preparation protocols and assay conditions, CoMoCAT DM-SWNT dispersions are not inherently cytotoxic to HeLa cells. We conclude with recommendations for improving the accuracy and comparability of carbon nanotube (CNT) cytotoxicity reports.

No MeSH data available.


Weight percent and derivative of weight percent curves for the thermal gravimetric analysis of the as-received CoMoCAT SWNT-containing powder in oxygen.
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Figure 2: Weight percent and derivative of weight percent curves for the thermal gravimetric analysis of the as-received CoMoCAT SWNT-containing powder in oxygen.

Mentions: TGA of the as-received SWNT-containing powder was performed to assess the powder's composition with respect to metals, SWNTs, and non-tubular carbon (NTC) species such as amorphous carbons, fullerenes, carbides, graphitic nanoparticles, etc. TGA measurements of the SWNT-containing powder were performed under the assumption that upon heating to 1000°C in O2, all carbon and metals were converted to their corresponding oxides, and that the presence of other trace elements could introduce small errors to calculated metal contents [106]. Figure 2 shows the weight percent decrease as a function of temperature (red trace) and the first derivative of the weight percent curve (blue trace) for the as-received SWNT-containing powder. The identities of the components corresponding to the three main peaks observed in the derivative plot were determined in experiments whereby the residues in the TGA pan were recovered and analyzed by Raman spectroscopy and/or XPS before, during, and after peak onset. In brief, peak 'a' at ~410°C was determined to comprise SWNTs based on the appearance of a strong G-band – a Raman resonance uniquely associated with SWNTs. The oxidation temperature of the SWNTs ranged between 375–450°C and was consistent with the oxidation temperature of CoMoCAT SWNTs observed by Resasco and co-workers [105]. Peak 'b' at ~505°C was determined to comprise NTCs based on the disappearance of the G-band and an increase of the D-band – a Raman resonance uniquely associated with miscellaneous forms of disordered carbon. Peak 'c' at ~700°C, 9% weight loss, was determined to comprise MoO3 by XPS and was supported by the ~700°C sublimation temperature of MoO3. XPS experiments also ruled out the presence of residual SiO2 in the as-received SWNT-containing powder. The remaining 5% mass at 1000°C (Figure 2, red trace) was considered to be oxidized metals of Co and Mo, most likely CoMoO4 and MoO2. In summary, the oxidized SWNT-containing powder was classified as comprising ~70% SWNTs, ~7% NTC, and ~14% oxidized metals.


Single-walled carbon nanotube interactions with HeLa cells.

Yehia HN, Draper RK, Mikoryak C, Walker EK, Bajaj P, Musselman IH, Daigrepont MC, Dieckmann GR, Pantano P - J Nanobiotechnology (2007)

Weight percent and derivative of weight percent curves for the thermal gravimetric analysis of the as-received CoMoCAT SWNT-containing powder in oxygen.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2131758&req=5

Figure 2: Weight percent and derivative of weight percent curves for the thermal gravimetric analysis of the as-received CoMoCAT SWNT-containing powder in oxygen.
Mentions: TGA of the as-received SWNT-containing powder was performed to assess the powder's composition with respect to metals, SWNTs, and non-tubular carbon (NTC) species such as amorphous carbons, fullerenes, carbides, graphitic nanoparticles, etc. TGA measurements of the SWNT-containing powder were performed under the assumption that upon heating to 1000°C in O2, all carbon and metals were converted to their corresponding oxides, and that the presence of other trace elements could introduce small errors to calculated metal contents [106]. Figure 2 shows the weight percent decrease as a function of temperature (red trace) and the first derivative of the weight percent curve (blue trace) for the as-received SWNT-containing powder. The identities of the components corresponding to the three main peaks observed in the derivative plot were determined in experiments whereby the residues in the TGA pan were recovered and analyzed by Raman spectroscopy and/or XPS before, during, and after peak onset. In brief, peak 'a' at ~410°C was determined to comprise SWNTs based on the appearance of a strong G-band – a Raman resonance uniquely associated with SWNTs. The oxidation temperature of the SWNTs ranged between 375–450°C and was consistent with the oxidation temperature of CoMoCAT SWNTs observed by Resasco and co-workers [105]. Peak 'b' at ~505°C was determined to comprise NTCs based on the disappearance of the G-band and an increase of the D-band – a Raman resonance uniquely associated with miscellaneous forms of disordered carbon. Peak 'c' at ~700°C, 9% weight loss, was determined to comprise MoO3 by XPS and was supported by the ~700°C sublimation temperature of MoO3. XPS experiments also ruled out the presence of residual SiO2 in the as-received SWNT-containing powder. The remaining 5% mass at 1000°C (Figure 2, red trace) was considered to be oxidized metals of Co and Mo, most likely CoMoO4 and MoO2. In summary, the oxidized SWNT-containing powder was classified as comprising ~70% SWNTs, ~7% NTC, and ~14% oxidized metals.

Bottom Line: Transmission electron microscopy revealed SWNT-like material in intracellular vacuoles.The combined results indicate that under our sample preparation protocols and assay conditions, CoMoCAT DM-SWNT dispersions are not inherently cytotoxic to HeLa cells.We conclude with recommendations for improving the accuracy and comparability of carbon nanotube (CNT) cytotoxicity reports.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemistry, The University of Texas at Dallas, Richardson, TX 75080, USA. pantano@utdallas.edu.

ABSTRACT
This work concerns exposing cultured human epithelial-like HeLa cells to single-walled carbon nanotubes (SWNTs) dispersed in cell culture media supplemented with serum. First, the as-received CoMoCAT SWNT-containing powder was characterized using scanning electron microscopy and thermal gravimetric analyses. Characterizations of the purified dispersions, termed DM-SWNTs, involved atomic force microscopy, inductively coupled plasma - mass spectrometry, and absorption and Raman spectroscopies. Confocal microRaman spectroscopy was used to demonstrate that DM-SWNTs were taken up by HeLa cells in a time- and temperature-dependent fashion. Transmission electron microscopy revealed SWNT-like material in intracellular vacuoles. The morphologies and growth rates of HeLa cells exposed to DM-SWNTs were statistically similar to control cells over the course of 4 d. Finally, flow cytometry was used to show that the fluorescence from MitoSOXtrade mark Red, a selective indicator of superoxide in mitochondria, was statistically similar in both control cells and cells incubated in DM-SWNTs. The combined results indicate that under our sample preparation protocols and assay conditions, CoMoCAT DM-SWNT dispersions are not inherently cytotoxic to HeLa cells. We conclude with recommendations for improving the accuracy and comparability of carbon nanotube (CNT) cytotoxicity reports.

No MeSH data available.