Dr. Huan-Cheng Chang - Magnetically Modulated Fluorescence of Nitrogen-Vacancy Centers in Nanodiam

Magnetically Modulated Fluorescence of Nitrogen-Vacancy Centers in Nanodiamonds for Ultrasensitive Biomedical Analysis

Yuen Yung Hui,¹ Oliver J. Chen,¹ Hsin-Hung Lin,¹ Yu-Kai Su,¹ Katherine Y. Chen,¹ Chih-Yen Wang,¹ Wesley W.-W. Hsiao,² and Huan-Cheng Chang^1,2,3,*

¹Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan

²Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan

³Department of Chemistry, National Normal Taiwan University, Taipei 106, Taiwan

Anal. Chem. 93, 7140–7147 (2021).

The negatively charged nitrogen-vacancy (NV^–) center in fluorescent nanodiamond (FND) 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 surface or dispersed in solution with a lock-in detection method. We achieved selective and sensitive detection of 100-nm FNDs on nitrocellulose membrane at a particle density of 0.04 ng/mm² (or ~2 × 10⁴ particles/mm²) and in 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. [link]

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