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Article

Unraveling Origins of EPR Spectrum in Graphene Oxide Quantum Dots

1
Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań, Poland
2
School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
*
Author to whom correspondence should be addressed.
Nanomaterials 2020, 10(4), 798; https://doi.org/10.3390/nano10040798
Received: 19 February 2020 / Revised: 12 March 2020 / Accepted: 17 April 2020 / Published: 21 April 2020
(This article belongs to the Special Issue Nanocarbon Based Materials)
Carbon nanostructures are utilized in a plethora of applications ranging from biomedicine to electronics. Particularly interesting are carbon nanostructured quantum dots that can be simultaneously used for bimodal therapies with both targeting and imaging capabilities. Here, magnetic and optical properties of graphene oxide quantum dots (GOQDs) prepared by the top-down technique from graphene oxide and obtained using the Hummers’ method were studied. Graphene oxide was ultra-sonicated, boiled in HNO3, ultra-centrifuged, and finally filtrated, reaching a mean flake size of ~30 nm with quantum dot properties. Flake size distributions were obtained from scanning electron microscopy (SEM) images after consecutive preparation steps. Energy-dispersive X-ray (EDX) confirmed that GOQDs were still oxidized after the fabrication procedure. Magnetic and photoluminescence measurements performed on the obtained GOQDs revealed their paramagnetic behavior and broad range optical photoluminescence around 500 nm, with magnetic moments of 2.41 µB. Finally, electron paramagnetic resonance (EPR) was used to separate the unforeseen contributions and typically not taken into account metal contaminations, and radicals from carbon defects. This study contributes to a better understanding of magnetic properties of carbon nanostructures, which could in the future be used for the design of multimodal imaging agents. View Full-Text
Keywords: graphene oxide; quantum dots; EPR; magnetism; photoluminescence graphene oxide; quantum dots; EPR; magnetism; photoluminescence
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MDPI and ACS Style

Tadyszak, K.; Musiał, A.; Ostrowski, A.; Wychowaniec, J.K. Unraveling Origins of EPR Spectrum in Graphene Oxide Quantum Dots. Nanomaterials 2020, 10, 798. https://doi.org/10.3390/nano10040798

AMA Style

Tadyszak K, Musiał A, Ostrowski A, Wychowaniec JK. Unraveling Origins of EPR Spectrum in Graphene Oxide Quantum Dots. Nanomaterials. 2020; 10(4):798. https://doi.org/10.3390/nano10040798

Chicago/Turabian Style

Tadyszak, Krzysztof, Andrzej Musiał, Adam Ostrowski, and Jacek K. Wychowaniec 2020. "Unraveling Origins of EPR Spectrum in Graphene Oxide Quantum Dots" Nanomaterials 10, no. 4: 798. https://doi.org/10.3390/nano10040798

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