Quantum relaxometry for detecting biomolecular interactions with single NV centers
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2025-08-25 |
| Journal | Proceedings of the National Academy of Sciences |
| Authors | Min Li, Qi Zhang, Xi Kong, Sheng Zhao, Baishen Pan |
| Institutions | Hefei University, Nankai University |
Abstract
Section titled āAbstractāThe investigation of biomolecular interactions at the single-molecule level has emerged as a pivotal research area in life science, particularly through optical, mechanical, and electrochemical approaches. Spins existing widely in biological systems offer a unique degree of freedom for detecting such interactions. However, most previous studies have been largely confined to ensemble-level detection in the spin degree. Here, we developed a molecular interaction analysis method approaching single-molecule level based on relaxometry using the quantum sensor, nitrogen-vacancy (NV) center in diamond. Experiments utilized an optimized diamond surface functionalized with a polyethylenimine nanogel layer, achieving <mml:math xmlns:mml=āhttp://www.w3.org/1998/Math/MathMLā display=āinlineā overflow=āscrollā> <mml:mo>ā¼</mml:mo> </mml:math> 10 nm average protein distance and mitigating interfacial steric hindrance. Then we measured the strong interaction between streptavidin and spin-labeled biotin complexes, as well as the weak interaction between bovine serum albumin and biotin complexes, at both the micrometer scale and nanoscale. For the micrometer-scale measurements using ensemble NV centers, we reexamined the often-neglected fast relaxation component and proposed a relaxation rate evaluation method, substantially enhancing the measurement sensitivity. Furthermore, we achieved nanoscale detection approaching single-molecule level using single NV centers. This methodology holds promise for applications in molecular screening, identification, and kinetic studies at the single-molecule level, offering critical insights into molecular function and activity mechanisms.