Bright Quantum-Grade Fluorescent Nanodiamonds
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2024-12-16 |
| Journal | ACS Nano |
| Authors | Keisuke Oshimi, Hitoshi Ishiwata, Hiromu Nakashima, Sara MandiÄ, Hina Kobayashi |
| Institutions | Japan Advanced Institute of Science and Technology, Okayama University |
| Citations | 9 |
Abstract
Section titled āAbstractāOptically accessible spin-active nanomaterials are promising as quantum nanosensors for probing biological samples. However, achieving bioimaging-level brightness and high-quality spin properties for these materials is challenging and hinders their application in quantum biosensing. Here, we demonstrate bright fluorescent nanodiamonds (NDs) containing 0.6-1.3-ppm negatively charged nitrogen-vacancy (NV) centers by spin-environment engineering via enriching spin-less <sup>12</sup>C-carbon isotopes and reducing substitutional nitrogen spin impurities. The NDs, readily introduced into cultured cells, exhibited improved optically detected magnetic resonance (ODMR) spectra; peak splitting (<i>E</i>) was reduced by 2-3 MHz, and microwave excitation power required was 20 times lower to achieve a 3% ODMR contrast, comparable to that of conventional type-Ib NDs. They show average spin-relaxation times of <i>T</i><sub>1</sub> = 0.68 ms and <i>T</i><sub>2</sub> = 3.2 Ī¼s (1.6 ms and 5.4 Ī¼s maximum) that were 5- and 11-fold longer than those of type-Ib, respectively. Additionally, the extended <i>T</i><sub>2</sub> relaxation times of these NDs enable shot-noise-limited temperature measurements with a sensitivity of approximately <mml:math xmlns:mml=āhttp://www.w3.org/1998/Math/MathMLā><mml:mn>0.28</mml:mn><mml:mspace></mml:mspace><mml:mi>K</mml:mi><mml:mo>/</mml:mo><mml:msqrt><mml:mi>Hz</mml:mi></mml:msqrt></mml:math>. The combination of bulk-like NV spin properties and enhanced fluorescence significantly improves the sensitivity of ND-based quantum sensors for biological applications.