Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo namesti 2, 166 10 Prague, Czechia.
Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague 2, Czechia.
ACS Nano. 2020 Oct 27;14(10):12938-12950. doi: 10.1021/acsnano.0c04010. Epub 2020 Aug 19.
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 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 mol in a localized volume). The detection is based on 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.
用于灵敏检测顺磁物种和与其（生物）化学转化相关的分子的生物相容性纳米级探针将为更好地了解细胞氧化还原过程提供一种理想的工具。在这里，我们描述了一种基于量子传感技术的分析工具。我们将纳米金刚石 (ND) 中的带负电荷的氮空位 (NV) 中心与 ND 生物惰性聚合物涂层中存在的氮氧化物自由基磁性耦合。我们证明，NV 中心的自旋弛豫时间对氮氧化物自由基的数量非常敏感，分辨率可低至 ∼10 个每 ND（局部体积中检测到大约 10 摩尔）。检测基于自由基附着时的缩短，我们提出了一个描述这一现象的理论模型。我们进一步表明，这种胶体稳定、水溶性系统可在环境条件下在水相环境中在 ND 表面附近用于氧化还原化学过程（抗坏血酸氧化）的时空读出。
