Bright Quantum-Grade Fluorescent Nanodiamonds.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39681540.
- Also identified by DOI 10.1021/acsnano.4c03424 and PMC identifier 11697348.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Optically 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 μs (1.6 ms and 5.4 μs 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 <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>0.28</mn><mspace></mspace><mi>K</mi><mo>/</mo><msqrt><mi>Hz</mi></msqrt></math>. The combination of bulk-like NV spin properties and enhanced fluorescence significantly improves the sensitivity of ND-based quantum sensors for biological applications.