Nanoscale Dynamic Readout of a Chemical Redox Process Using Radicals Coupled with Nitrogen-Vacancy Centers in Nanodiamonds.
basic_science · Level V
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- Record sourced from PubMed, PMID 32790348.
- Also identified by DOI 10.1021/acsnano.0c04010.
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Abstract
Biocompatible nanoscale probes for sensitive detection of paramagnetic species and molecules associated with their (bio)chemical transformations would provide a desirable tool for a better understanding of cellular redox processes. Here, we describe an analytical tool based on quantum sensing techniques. We magnetically coupled negatively charged nitrogen-vacancy (NV) centers in nanodiamonds (NDs) with nitroxide radicals present in a bioinert polymer coating of the NDs. We demonstrated that the <i>T</i><sub>1</sub> spin relaxation time of the NV centers is very sensitive to the number of nitroxide radicals, with a resolution down to ∼10 spins per ND (detection of approximately 10<sup>-23</sup> mol in a localized volume). The detection is based on <i>T</i><sub>1</sub> shortening upon the radical attachment, and we propose a theoretical model describing this phenomenon. We further show that this colloidally stable, water-soluble system can be used dynamically for spatiotemporal readout of a redox chemical process (oxidation of ascorbic acid) occurring near the ND surface in an aqueous environment under ambient conditions.