Department of Biomedical Engineering, University Medical Center Groningen, Groningen University, Antonius Deusinglaan 1, 9713 AW Groningen, The Netherlands.
Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
ACS Sens. 2020 Dec 24;5(12):3862-3869. doi: 10.1021/acssensors.0c01037. Epub 2020 Dec 3.
Diamond magnetometry is a quantum sensing method involving detection of magnetic resonances with nanoscale resolution. For instance, T1 relaxation measurements, inspired by equivalent concepts in magnetic resonance imaging (MRI), provide a signal that is equivalent to T1 in conventional MRI but in a nanoscale environment. We use nanodiamonds (between 40 and 120 nm) containing ensembles of specific defects called nitrogen vacancy (NV) centers. To perform a T1 relaxation measurement, we pump the NV center in the ground state (using a laser at 532 nm) and observe how long the NV center can remain in this state. Here, we use this method to provide real-time measurements of free radicals when they are generated in a chemical reaction. Specifically, we focus on the photolysis of HO as well as the so-called Haber-Weiss reaction. Both of these processes are important reactions in biological environments. Unlike other fluorescent probes, diamonds are able to determine spin noise from different species in real time. We also investigate different diamond probes and their ability to sense gadolinium spin labels. Although this study was performed in a clean environment, we take into account the effects of salts and proteins that are present in a biological environment. We conduct our experiments with nanodiamonds, which are compatible with intracellular measurements. We perform measurements between 0 and 10 nM, and we are able to reach detection limits down to the nanomolar range and typically find T1 times of a few 100 μs. This is an important step toward label-free nano-MRI signal quantification in biological environments.
金刚石磁力计是一种量子传感方法，涉及使用纳米级分辨率检测磁共振。例如，T1 弛豫测量受到磁共振成像（MRI）等效概念的启发，提供了与传统 MRI 中 T1 等效但在纳米级环境中的信号。我们使用纳米金刚石（40 至 120nm 之间），其中包含称为氮空位（NV）中心的特定缺陷的集合体。为了进行 T1 弛豫测量，我们将 NV 中心泵入基态（使用 532nm 的激光），并观察 NV 中心可以在该状态下保持多长时间。在这里，我们使用这种方法实时测量化学反应中自由基的生成情况。具体来说，我们专注于 HO 的光解以及所谓的 Haber-Weiss 反应。这两个过程都是生物环境中的重要反应。与其他荧光探针不同，金刚石能够实时确定来自不同物种的自旋噪声。我们还研究了不同的金刚石探针及其感测钆自旋标记的能力。尽管这项研究是在清洁环境中进行的，但我们考虑了生物环境中存在的盐和蛋白质的影响。我们使用与细胞内测量兼容的纳米金刚石进行实验。我们在 0 到 10nM 之间进行测量，并且能够达到纳摩尔范围的检测极限，通常发现 T1 时间为数微秒。这是在生物环境中进行无标记纳米 MRI 信号定量的重要步骤。
