Academia Sinica, Institute of Atomic and Molecular Sciences, Taipei 106, Taiwan.
Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan.
Anal Chem. 2021 May 11;93(18):7140-7147. doi: 10.1021/acs.analchem.1c01224. Epub 2021 Apr 29.
The negatively charged nitrogen-vacancy center in fluorescent nanodiamonds (FNDs) is a point defect with unique magneto-optical properties. It emits far-red fluorescence at ∼700 nm, and its intensity can be magnetically modulated with a depth of more than 10% at a field strength of 30 mT. We have closely examined this property and illustrated its practical use in biomedicine by applying a periodic, time-varying magnetic field to FNDs deposited on a surface or dispersed in a solution with a lock-in detection method. We achieved selective and sensitive detection of 100 nm FNDs on a nitrocellulose membrane at a particle density of 0.04 ng/mm (or ∼2 × 10 particles/mm) and in an aqueous solution with a particle concentration of 1 ng/mL (or ∼1 fM) in 10 s as the detection limits. The utility and versatility of the technique were demonstrated with an application to background-free detection of FNDs as reporters for FND-based lateral flow immunoassays as well as selective quantification of FNDs in tissue digests for in vivo studies.
荧光纳米金刚石（FNDs）中的带负电荷的氮空位中心是一种具有独特磁光特性的点缺陷。它在约 700nm 处发射远红色荧光，其强度可以在 30mT 的磁场强度下通过超过 10%的深度进行磁调制。我们已经仔细研究了这一特性，并通过应用周期性、时变磁场到沉积在表面上的 FNDs 或分散在溶液中的 FNDs，使用锁相检测方法，说明了它在生物医学中的实际应用。我们在 10s 内实现了对 100nm FNDs 的选择性和灵敏检测，检测限为在硝化纤维素膜上的 0.04ng/mm（或约 2×10 个颗粒/mm）的颗粒密度和在 1ng/mL（或约 1fM）的颗粒浓度的水溶液中。该技术的实用性和多功能性通过应用于无背景的 FND 检测作为基于 FND 的侧向流动免疫分析的报告物以及用于体内研究的组织消化物中 FND 的选择性定量得到了证明。
