The USTC realizes In situ electron paramagnet

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Credit: USTC

Teams led by Prof. DU Jiangfeng, Prof. SHI Fazhan and Prof. KONG Fei from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) used the Nitrogen Vacancy (NV) center in one nanodiamond for quantum sensing to overcome the problem of random particle rotation.

The study was published on October 7 in Nature communication.

It is an important goal to detect and analyze molecules under physiological in situ conditions in the field of life sciences. Only by observing biomolecules under these conditions can we reveal conformational changes as they realize physiological functions.

Due to its high sensitivity, good biocompatibility and the characteristics of magnetic resonance detection of single molecules at room temperature, the NV center quantum sensor is more suitable for physiological in situ detection than traditional magnetic spectrum resonance instruments.

However, the results of tracking the motion of nanodiamond in living cells show that it rotates randomly both inside the cell and on the cell membrane, making current general magnetic resonance detection methods ineffective.

To solve this problem, the research team designed an amplitude modulation sequence, which will generate a series of evenly distributed energy levels in the NV center.

When the energy level of the NV center matches the energy level of the measured target, resonance will occur and the state of the NV center will change.

By scanning the modulation frequency, the electron paramagnetic resonance (EPR) spectroscopy of the target can be obtained, and the position of the spectral peak is no longer affected by the spatial orientation of the NV center.

In this work, the ions in the solution environment of nanodiamond were measured by EPR spectroscopy under the conditions of in situ. The research team simulated the movement of nanodiamonds within the cell to detect the dissolution of oxygen-vanadium ions.

When there is rotation of nanodiamonds, it is difficult to perform precise quantum manipulation of NV centers, but the zero-field EPR spectrum of oxo-vanadium ions can still be measured.

This result basically proves that it is feasible to use the NV center in nanodiamonds to realize the detection of intracellular physiological in-situ magnetic resonance.

The oxygen-vanadium ions detected in this work have biological functions themselves. The ultrafine constant of oxygen-vanadium ions can be analyzed and obtained by the EPR spectrum measured by a single moving nanodiamond.

The research team previously relaxed the detection conditions of single-molecule magnetic resonance detection from solid conditions to an aqueous solution environment, and this work further promoted this to the in situ environment.

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