Defect-Activated and Surface-Modified Hexagonal Boron Nitride Nanoparticles toward Intracellular Quantum Sensing.

Shimomura, Suzune; Nakane, Yurina; Abe, Hiroshi; Miyake, Yusuke; Ohshima, Takeshi; Yoshida, Yumi; Maeda, Kohji; Sugi, Takuma et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

van der Waals materials hosting spin defects have emerged as a new platform for solid-state quantum sensing. We report hexagonal boron nitride (hBN) nanoparticles containing negatively charged boron vacancy (<i>V</i><sub><i>B</i></sub><sup>-</sup>) centers that function as nanoscale quantum sensors. High-energy electron irradiation efficiently generated <i>V</i><sub><i>B</i></sub><sup>-</sup> centers, enabling clear optically detected magnetic resonance (ODMR) detection from nanoparticle ensembles. To improve dispersion and suppress nonspecific protein adsorption, we developed a two-step surface modification process using silica encapsulation followed by hyperbranched polyglycerol (HPG) grafting. The HPG coating enhanced colloidal stability and reduced nonspecific protein adsorption. ODMR thermometry revealed temperature-dependent frequency shifts with a thermal coefficient of approximately - 300 kHz/°C. Finally, we demonstrated proof-of-concept detection of ODMR signal in HeLa cells after uptake of the nanoparticles. These results establish <i>V</i><sub><i>B</i></sub><sup>-</sup>-containing hBN nanoparticles as promising nanoscale quantum sensors for future intracellular applications.