Benchtop Fluorination of Fluorescent Nanodiamonds on a Preparative Scale: Toward Unusually Hydrophilic Bright Particles

Authors

  • Jan Havlik,

    1. Institute of Organic Chemistry and Biochemistry ASCR, Prague 6, Czech Republic
    2. Faculty of Science, Charles University, Prague 2, Czech Republic
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  • Helena Raabova,

    1. Institute of Organic Chemistry and Biochemistry ASCR, Prague 6, Czech Republic
    2. Department of Inorganic Chemistry, University of Chemistry and Technology Prague, Prague 6, Czech Republic
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  • Michal Gulka,

    1. Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno, Czech Republic
    2. Institute of Physics, ASCR, Prague 8, Czech Republic
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  • Vladimira Petrakova,

    1. Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno, Czech Republic
    2. Institute of Physics, ASCR, Prague 8, Czech Republic
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  • Marie Krecmarova,

    1. Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno, Czech Republic
    2. Institute for Materials Research (IMO), Hasselt University, Diepenbeek, Belgium
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  • Vlastimil Masek,

    1. Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czech Republic
    2. Department of Pharmacology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czech Republic
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  • Petr Lousa,

    1. Institute of Organic Chemistry and Biochemistry ASCR, Prague 6, Czech Republic
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  • Jan Stursa,

    1. Nuclear Physics Institute AS CR, Prague, Czech Republic
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  • Hans-Gerd Boyen,

    1. Institute for Materials Research (IMO), Hasselt University, Diepenbeek, Belgium
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  • Milos Nesladek,

    1. Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno, Czech Republic
    2. Institute for Materials Research (IMO), Hasselt University, Diepenbeek, Belgium
    3. IMEC Division IMOMEC, Hasselt University, Diepenbeek, Belgium
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  • Petr Cigler

    Corresponding author
    1. Institute of Organic Chemistry and Biochemistry ASCR, Prague 6, Czech Republic
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Abstract

Fluorination of diamonds modulates their optical and electromagnetic properties and creates surfaces with increased hydrophobicity. In addition, fluorination of diamonds and nanodiamonds has been recently shown to stabilize fluorescent nitrogen-vacancy centers, which can serve as extremely sensitive single atomic defects in a vast range of sensing applications from quantum physics to high-resolution biological imaging. Traditionally, fluorination of carbon nanomaterials has been achieved using harsh and complex experimental conditions, creating hydrophobic interfaces with difficult dispersibility in aqueous environments. Here, a mild benchtop approach to nanodiamond fluorination is described using selective Ag+-catalyzed radical substitution of surface carboxyls for fluorine. In contrast to other approaches, this high-yielding procedure does not etch diamond carbons and produces a highly hydrophilic interface with mixed C−F and C−OH termination. This dual functionalization of nanodiamonds suppresses detrimental hydrophobic interactions that would lead to colloidal destabilization of nanodiamonds. It is also demonstrated that even a relatively low surface density of fluorine contributes to stabilization of negatively charged nitrogen-vacancy centers and boosts their fluorescence. The simultaneous control of the surface hydrophilicity and the fluorescence of nitrogen-vacancy centers is an important issue enabling direct application of fluorescent nanodiamonds as nanosensors for quantum optical and magnetometry measurements operated in biological environment.

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