Highly efficient conversion of superoxide to oxygen using hydrophilic carbon clusters

Errol L G Samuel; Daniela C. Marcano; Vladimir Berka; Brittany R. Bitner; Gang Wu; Austin Potter; Roderic H. Fabian; Robia G. Pautler; Thomas A. Kent; Ah Lim Tsai; James M. Tour

doi:10.1073/pnas.1417047112

Highly efficient conversion of superoxide to oxygen using hydrophilic carbon clusters

Errol L G Samuel, Daniela C. Marcano, Vladimir Berka, Brittany R. Bitner, Gang Wu, Austin Potter, Roderic H. Fabian, Robia G. Pautler, Thomas A. Kent, Ah Lim Tsai, James M. Tour

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165 Scopus citations

Abstract

Many diseases are associated with oxidative stress, which occurs when the production of reactive oxygen species (ROS) overwhelms the scavenging ability of an organism. Here, we evaluated the carbon nanoparticle antioxidant properties of poly(ethylene glycolated) hydrophilic carbon clusters (PEG-HCCs) by electron paramagnetic resonance (EPR) spectroscopy, oxygen electrode, and spectrophotometric assays. These carbon nanoparticles have 1 equivalent of stable radical and showed superoxide (O₂^•-) dismu-tase-like properties yet were inert to nitric oxide (NO•) as well as peroxynitrite (ONOO-). Thus, PEG-HCCs can act as selective antioxidants that do not require regeneration by enzymes. Our steadystate kinetic assay using KO₂ and direct freeze-trap EPR to follow its decay removed the rate-limiting substrate provision, thus enabling determination of the remarkable intrinsic turnover numbers of O₂^•-to O₂ by PEG-HCCs at >20,000 s^-1 . Themajor products of this catalytic turnover are O₂ and H ₂ O ₂, making the PEG-HCCs a biomimetic superoxide dismutase.

Original language	English (US)
Pages (from-to)	2343-2348
Number of pages	6
Journal	Proceedings of the National Academy of Sciences of the United States of America
Volume	112
Issue number	8
DOIs	https://doi.org/10.1073/pnas.1417047112
State	Published - Feb 24 2015

Keywords

Antioxidant
Carbon nanoparticles
Hydrophilic carbon clusters
Superoxide
Superoxide dismutase mimetic

ASJC Scopus subject areas

General

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10.1073/pnas.1417047112

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Samuel, E. L. G., Marcano, D. C., Berka, V., Bitner, B. R., Wu, G., Potter, A., Fabian, R. H., Pautler, R. G., Kent, T. A., Tsai, A. L., & Tour, J. M. (2015). Highly efficient conversion of superoxide to oxygen using hydrophilic carbon clusters. Proceedings of the National Academy of Sciences of the United States of America, 112(8), 2343-2348. https://doi.org/10.1073/pnas.1417047112

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abstract = "Many diseases are associated with oxidative stress, which occurs when the production of reactive oxygen species (ROS) overwhelms the scavenging ability of an organism. Here, we evaluated the carbon nanoparticle antioxidant properties of poly(ethylene glycolated) hydrophilic carbon clusters (PEG-HCCs) by electron paramagnetic resonance (EPR) spectroscopy, oxygen electrode, and spectrophotometric assays. These carbon nanoparticles have 1 equivalent of stable radical and showed superoxide (O2•-) dismu-tase-like properties yet were inert to nitric oxide (NO•) as well as peroxynitrite (ONOO-). Thus, PEG-HCCs can act as selective antioxidants that do not require regeneration by enzymes. Our steadystate kinetic assay using KO2 and direct freeze-trap EPR to follow its decay removed the rate-limiting substrate provision, thus enabling determination of the remarkable intrinsic turnover numbers of O2•-to O2 by PEG-HCCs at >20,000 s-1 . Themajor products of this catalytic turnover are O2 and H 2 O 2, making the PEG-HCCs a biomimetic superoxide dismutase.",

keywords = "Antioxidant, Carbon nanoparticles, Hydrophilic carbon clusters, Superoxide, Superoxide dismutase mimetic",

author = "Samuel, {Errol L G} and Marcano, {Daniela C.} and Vladimir Berka and Bitner, {Brittany R.} and Gang Wu and Austin Potter and Fabian, {Roderic H.} and Pautler, {Robia G.} and Kent, {Thomas A.} and Tsai, {Ah Lim} and Tour, {James M.}",

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AU - Samuel, Errol L G

AU - Marcano, Daniela C.

AU - Berka, Vladimir

AU - Bitner, Brittany R.

AU - Wu, Gang

AU - Potter, Austin

AU - Fabian, Roderic H.

AU - Pautler, Robia G.

AU - Kent, Thomas A.

AU - Tsai, Ah Lim

AU - Tour, James M.

PY - 2015/2/24

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N2 - Many diseases are associated with oxidative stress, which occurs when the production of reactive oxygen species (ROS) overwhelms the scavenging ability of an organism. Here, we evaluated the carbon nanoparticle antioxidant properties of poly(ethylene glycolated) hydrophilic carbon clusters (PEG-HCCs) by electron paramagnetic resonance (EPR) spectroscopy, oxygen electrode, and spectrophotometric assays. These carbon nanoparticles have 1 equivalent of stable radical and showed superoxide (O2•-) dismu-tase-like properties yet were inert to nitric oxide (NO•) as well as peroxynitrite (ONOO-). Thus, PEG-HCCs can act as selective antioxidants that do not require regeneration by enzymes. Our steadystate kinetic assay using KO2 and direct freeze-trap EPR to follow its decay removed the rate-limiting substrate provision, thus enabling determination of the remarkable intrinsic turnover numbers of O2•-to O2 by PEG-HCCs at >20,000 s-1 . Themajor products of this catalytic turnover are O2 and H 2 O 2, making the PEG-HCCs a biomimetic superoxide dismutase.

AB - Many diseases are associated with oxidative stress, which occurs when the production of reactive oxygen species (ROS) overwhelms the scavenging ability of an organism. Here, we evaluated the carbon nanoparticle antioxidant properties of poly(ethylene glycolated) hydrophilic carbon clusters (PEG-HCCs) by electron paramagnetic resonance (EPR) spectroscopy, oxygen electrode, and spectrophotometric assays. These carbon nanoparticles have 1 equivalent of stable radical and showed superoxide (O2•-) dismu-tase-like properties yet were inert to nitric oxide (NO•) as well as peroxynitrite (ONOO-). Thus, PEG-HCCs can act as selective antioxidants that do not require regeneration by enzymes. Our steadystate kinetic assay using KO2 and direct freeze-trap EPR to follow its decay removed the rate-limiting substrate provision, thus enabling determination of the remarkable intrinsic turnover numbers of O2•-to O2 by PEG-HCCs at >20,000 s-1 . Themajor products of this catalytic turnover are O2 and H 2 O 2, making the PEG-HCCs a biomimetic superoxide dismutase.

KW - Antioxidant

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KW - Hydrophilic carbon clusters

KW - Superoxide

KW - Superoxide dismutase mimetic

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Highly efficient conversion of superoxide to oxygen using hydrophilic carbon clusters

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