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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.

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Experimental NMRD profiles (dots), and best fits (solid lines) derived from SBM Theory for (a) Oxidized Graphite, (b) Graphene Nanoplatelets, (c) Reduced Graphene Nanoplatelets, and d) Graphene Nanoribbons.
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pone-0038185-g005: Experimental NMRD profiles (dots), and best fits (solid lines) derived from SBM Theory for (a) Oxidized Graphite, (b) Graphene Nanoplatelets, (c) Reduced Graphene Nanoplatelets, and d) Graphene Nanoribbons.

Mentions: The NMRD profiles between 0.01–80 MHz of aqueous solutions of oxidized graphite, oxidized graphene nanoplatelets, reduced graphene nanoplatelets and graphene nanoribbons is presented in Figure 5a–d. This is the first report of longitudinal r1 relaxivities for these compounds over such a large magnetic field range (0.01–80). While oxidized micro-graphite and reduced graphene nanoplatelets show similar NMRD profiles, oxidized graphene nanoplatelets, and graphene nanoribbons show distinctly different profiles than these two samples. At mid-to-high magnetic field (<10 MHz), oxidized micro-graphite shows a smaller increase (50–66 mM−1s−1) with decrease in magnetic field, and a greater increase with decrease to lower magnetic fields (70–222 mM−1s−1). Oxidized graphene nanoplatelets shows bell shaped distribution at mid-to-high magnetic fields with a maximum of 55 mM−1s−1 at 30 MHz, and a gradual increase up to 86 mM1s−1 as the magnetic fields decrease below 10 MHz. Reduced graphene nanoplatelets shows a small increase (44–59 mM−1s−1) with decrease in magnetic field between 80–10 MHz, and the relaxivity increases at lower magnetic fields with a maximum value of 258 mM−1s−1 at 0.01 MHz. Graphene nanoribbons show a linear increase (relaxivity between 65–100 mM−1s−1) with decrease in magnetic fields up to 10 MHz, and then a continuous steep increase below 10 MHz reaching values of 724 mM−1s−1 at 0.01 MHz.


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)

Experimental NMRD profiles (dots), and best fits (solid lines) derived from SBM Theory for (a) Oxidized Graphite, (b) Graphene Nanoplatelets, (c) Reduced Graphene Nanoplatelets, and d) Graphene Nanoribbons.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0038185-g005: Experimental NMRD profiles (dots), and best fits (solid lines) derived from SBM Theory for (a) Oxidized Graphite, (b) Graphene Nanoplatelets, (c) Reduced Graphene Nanoplatelets, and d) Graphene Nanoribbons.
Mentions: The NMRD profiles between 0.01–80 MHz of aqueous solutions of oxidized graphite, oxidized graphene nanoplatelets, reduced graphene nanoplatelets and graphene nanoribbons is presented in Figure 5a–d. This is the first report of longitudinal r1 relaxivities for these compounds over such a large magnetic field range (0.01–80). While oxidized micro-graphite and reduced graphene nanoplatelets show similar NMRD profiles, oxidized graphene nanoplatelets, and graphene nanoribbons show distinctly different profiles than these two samples. At mid-to-high magnetic field (<10 MHz), oxidized micro-graphite shows a smaller increase (50–66 mM−1s−1) with decrease in magnetic field, and a greater increase with decrease to lower magnetic fields (70–222 mM−1s−1). Oxidized graphene nanoplatelets shows bell shaped distribution at mid-to-high magnetic fields with a maximum of 55 mM−1s−1 at 30 MHz, and a gradual increase up to 86 mM1s−1 as the magnetic fields decrease below 10 MHz. Reduced graphene nanoplatelets shows a small increase (44–59 mM−1s−1) with decrease in magnetic field between 80–10 MHz, and the relaxivity increases at lower magnetic fields with a maximum value of 258 mM−1s−1 at 0.01 MHz. Graphene nanoribbons show a linear increase (relaxivity between 65–100 mM−1s−1) with decrease in magnetic fields up to 10 MHz, and then a continuous steep increase below 10 MHz reaching values of 724 mM−1s−1 at 0.01 MHz.

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