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arXiv · 2312.17603

Quantum-grade nanodiamonds for ultrabright spin detection in live cells

Keisuke Oshimi·Hiromu Nakashima·Sara Mandić·Hina Kobayashi·Minori Teramoto·Hirokazu Tsuji·Yoshiki Nishibayashi·Yutaka Shikano·Toshu An·Masazumi Fujiwara
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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 ultrabright fluorescent nanodiamonds (NDs) containing 0.6-1.3-ppm nitrogen-vacancy (NV) centers by spin-environment engineering via enriching spin-less 12C-carbon isotopes and reducing substitutional nitrogen spin impurities. The NDs, readily introduced into cultured cells, exhibited substantially narrow optically detected magnetic resonance (ODMR) spectra, requiring 16-times less microwave excitation power to give an ODMR depth comparable to that of conventional type-Ib NDs. They show average spin-relaxation times of T1 = 0.68 ms and T_2 = 1.6 us (1.6 ms and 2.7 us maximum) that were 5- and 11-fold longer than those of type-Ib, respectively. The bulk-like NV spin properties and bright fluorescence demonstrated in this study significantly improve the sensitivity of ND-based quantum sensors for biological applications.

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Keisuke Oshimi, Hiromu Nakashima, Sara Mandić, Hina Kobayashi, Minori Teramoto, Hirokazu Tsuji, Yoshiki Nishibayashi, Yutaka Shikano, Toshu An, Masazumi Fujiwara. 2023-12-29. Quantum-grade nanodiamonds for ultrabright spin detection in live cells. https://doi.org/10.1021/acsnano.4c03424

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