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Physicochemical characterization, and relaxometry studies of micro-graphite oxide, graphene nanoplatelets, and nanoribbons.

Paratala BS, Jacobson BD, Kanakia S, Francis LD, Sitharaman B - PLoS ONE (2012)

Bottom Line: The chemistry of high-performance magnetic resonance imaging contrast agents remains an active area of research.In this work, we demonstrate that the potassium permanganate-based oxidative chemical procedures used to synthesize graphite oxide or graphene nanoparticles leads to the confinement (intercalation) of trace amounts of Mn(2+) ions between the graphene sheets, and that these manganese intercalated graphitic and graphene structures show disparate structural, chemical and magnetic properties, and high relaxivity (up to 2 order) and distinctly different nuclear magnetic resonance dispersion profiles compared to paramagnetic chelate compounds.The results taken together with other published reports on confinement of paramagnetic metal ions within single-walled carbon nanotubes (a rolled up graphene sheet) show that confinement (encapsulation or intercalation) of paramagnetic metal ions within graphene sheets, and not the size, shape or architecture of the graphitic carbon particles is the key determinant for increasing relaxivity, and thus, identifies nano confinement of paramagnetic ions as novel general strategy to develop paramagnetic metal-ion graphitic-carbon complexes as high relaxivity MRI contrast agents.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America.

ABSTRACT
The chemistry of high-performance magnetic resonance imaging contrast agents remains an active area of research. In this work, we demonstrate that the potassium permanganate-based oxidative chemical procedures used to synthesize graphite oxide or graphene nanoparticles leads to the confinement (intercalation) of trace amounts of Mn(2+) ions between the graphene sheets, and that these manganese intercalated graphitic and graphene structures show disparate structural, chemical and magnetic properties, and high relaxivity (up to 2 order) and distinctly different nuclear magnetic resonance dispersion profiles compared to paramagnetic chelate compounds. The results taken together with other published reports on confinement of paramagnetic metal ions within single-walled carbon nanotubes (a rolled up graphene sheet) show that confinement (encapsulation or intercalation) of paramagnetic metal ions within graphene sheets, and not the size, shape or architecture of the graphitic carbon particles is the key determinant for increasing relaxivity, and thus, identifies nano confinement of paramagnetic ions as novel general strategy to develop paramagnetic metal-ion graphitic-carbon complexes as high relaxivity MRI contrast agents.

Show MeSH
Magnetization (M) v/s Field strength (H) between −50,000 Oe and 50,000 Oe at 10, 150 and 300 K for (a) MWCNTs, and (b) graphene nanoribbons (Inset shows M versus H between −4000 Oe and 4000 Oe at 300 K), (c) ZFC and FC plots of graphene nanoribbons.
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pone-0038185-g002: Magnetization (M) v/s Field strength (H) between −50,000 Oe and 50,000 Oe at 10, 150 and 300 K for (a) MWCNTs, and (b) graphene nanoribbons (Inset shows M versus H between −4000 Oe and 4000 Oe at 300 K), (c) ZFC and FC plots of graphene nanoribbons.

Mentions: Figure 2 shows the SQUID magnetic characterization of MWCNTs (control), and graphene nanoribbons. Figure 2a shows the plot of magnetization (M) versus magnetic field strength (H) for the MWCNTs between −50,000 Oe and 50,000 Oe for three temperatures (10 K, 150 K, and 300 K). The plots show no coherent magnetic pattern, and the magnetic signals are extremely weak at all three temperatures indicating diamagnetic behavior despite the presence of iron catalysts in the MWCNTs.


Physicochemical characterization, and relaxometry studies of micro-graphite oxide, graphene nanoplatelets, and nanoribbons.

Paratala BS, Jacobson BD, Kanakia S, Francis LD, Sitharaman B - PLoS ONE (2012)

Magnetization (M) v/s Field strength (H) between −50,000 Oe and 50,000 Oe at 10, 150 and 300 K for (a) MWCNTs, and (b) graphene nanoribbons (Inset shows M versus H between −4000 Oe and 4000 Oe at 300 K), (c) ZFC and FC plots of graphene nanoribbons.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3369907&req=5

pone-0038185-g002: Magnetization (M) v/s Field strength (H) between −50,000 Oe and 50,000 Oe at 10, 150 and 300 K for (a) MWCNTs, and (b) graphene nanoribbons (Inset shows M versus H between −4000 Oe and 4000 Oe at 300 K), (c) ZFC and FC plots of graphene nanoribbons.
Mentions: Figure 2 shows the SQUID magnetic characterization of MWCNTs (control), and graphene nanoribbons. Figure 2a shows the plot of magnetization (M) versus magnetic field strength (H) for the MWCNTs between −50,000 Oe and 50,000 Oe for three temperatures (10 K, 150 K, and 300 K). The plots show no coherent magnetic pattern, and the magnetic signals are extremely weak at all three temperatures indicating diamagnetic behavior despite the presence of iron catalysts in the MWCNTs.

Bottom Line: The chemistry of high-performance magnetic resonance imaging contrast agents remains an active area of research.In this work, we demonstrate that the potassium permanganate-based oxidative chemical procedures used to synthesize graphite oxide or graphene nanoparticles leads to the confinement (intercalation) of trace amounts of Mn(2+) ions between the graphene sheets, and that these manganese intercalated graphitic and graphene structures show disparate structural, chemical and magnetic properties, and high relaxivity (up to 2 order) and distinctly different nuclear magnetic resonance dispersion profiles compared to paramagnetic chelate compounds.The results taken together with other published reports on confinement of paramagnetic metal ions within single-walled carbon nanotubes (a rolled up graphene sheet) show that confinement (encapsulation or intercalation) of paramagnetic metal ions within graphene sheets, and not the size, shape or architecture of the graphitic carbon particles is the key determinant for increasing relaxivity, and thus, identifies nano confinement of paramagnetic ions as novel general strategy to develop paramagnetic metal-ion graphitic-carbon complexes as high relaxivity MRI contrast agents.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York, United States of America.

ABSTRACT
The chemistry of high-performance magnetic resonance imaging contrast agents remains an active area of research. In this work, we demonstrate that the potassium permanganate-based oxidative chemical procedures used to synthesize graphite oxide or graphene nanoparticles leads to the confinement (intercalation) of trace amounts of Mn(2+) ions between the graphene sheets, and that these manganese intercalated graphitic and graphene structures show disparate structural, chemical and magnetic properties, and high relaxivity (up to 2 order) and distinctly different nuclear magnetic resonance dispersion profiles compared to paramagnetic chelate compounds. The results taken together with other published reports on confinement of paramagnetic metal ions within single-walled carbon nanotubes (a rolled up graphene sheet) show that confinement (encapsulation or intercalation) of paramagnetic metal ions within graphene sheets, and not the size, shape or architecture of the graphitic carbon particles is the key determinant for increasing relaxivity, and thus, identifies nano confinement of paramagnetic ions as novel general strategy to develop paramagnetic metal-ion graphitic-carbon complexes as high relaxivity MRI contrast agents.

Show MeSH