Nanodiamond-based quantum sensing in cell biology, drug screening and clinical diagnostics

Sparkling, hard and durable, these are some of the properties commonly associated with diamonds. These qualities have made them desirable within our society for centuries. In research, the unique properties of diamonds have drawn in many enthusiasts. Particularly, nanodiamonds with crystal lattice defects such as the negatively charged nitrogen-vacancy (NV-) centers, which have emerged as powerful and versatile quantum sensors. This talk focuses on a specific way to use the quantum-based sensing properties of nanodiamond with ensembles of NV- centers, a technique called relaxometry (or T1) and its application in cell biology. The key features of the NV− center are its optically detectable and controllable spin states. Analogously to T1 measurements in conventional magnetic resonance imaging (MRI), relaxometry allows the detection of different concentrations of paramagnetic species, including free radicals that are crucial in biological systems. However, unlike the MRI, it allows high-resolution localized measurements as the detected signals are from nanoscale voxels around the NV- center [1]. As a result, it is possible to achieve subcellular resolutions and organelle specific measurements inside single cells. Together with my colleagues we were the first researchers to apply nanodiamond-based T1 relaxometry to understand the multiple functions of free radicals (FR) in cell biology [2-5]. FRs are omnipresent and one of the key players in cellular signalling. Despite their relevance, information about FRs is sparse and therefore their use as clinical biomarkers is severely limited. Since FRs are short lived and reactive, it is challenging to detect them with the state-of-the-art methodology. So far, we have proven that the nanodiamond-based T1 relaxometry could be used for the real-time monitoring of changes in the concentration of free radicals at the level of single human cells [3], yeasts [4] and bacterial biofilms [5]. In my talk I will address a few exciting examples of biological processes and their clinical relevance where the role of free radicals was explored with relaxometry. I will stimulate discourse on the future of nanodiamond-based quantum sensing and how it can open new perspectives in cell biology, drug screening and clinical diagnostics.

1.    A. Mzyk, Y. Ong, A.R.O. Moreno, S. Padamati, Y. Zhang, C. A. Reyes-San-Martin, R. Schirhagl: Diamond color centers in nanodiamond for chemical and biochemical analysis and visualization, Analytical Chemistry (2021), 94(1): 225-249, doi:10.1021/acs.analchem.1c04536.
2.    A. Mzyk, A. Sigaeva, R. Schirhagl: Relaxometry with nitrogen vacancy (NV) centers in diamond, Accounts of Chemical Research (2022), 55(24): 3572-3580, doi.org/10.1021/acs.accounts.2c00520.
3.    C. Reyes-San-Martin, T. Hamoh, Y. Zhang, L. Berendse, C. Klijn, R. Li, A. Elías Llumbet, A. Sigaeva, J. Kawalko, A. Mzyk, R. Schirhagl: Nanoscale MRI for selective labelling and localised free radical measurements in the acrosomes of single sperm cells, ACS Nano (2022), 16(7): 10701-10710, doi.org/10.1021/acsnano.2c02511.
4.    A. Morita, A.C. Nusantara, A. Mzyk, F.P. Perona Martinez, T. Hamoh, V.G. Damle, K.J van der Laan, A. Sigaeva, T. Vedelaar, M. Chang, M. Chipaux, R. Schirhagl: Quantum monitoring the metabolism of individual yeast mutant strain cells when aged, stressed or treated with antioxidants, Nano Today (2023), 48: 101704, doi.org/10.1016/j.nantod.2022.101704.
5.    N. Norouzi, A. C. Nusantara, Y. Ong, T. Hamoh, L. Nie, A. Morita, Y. Zhang, A. Mzyk, R. Schirhagl: Relaxometry for Detecting Free Radical Generation During Bacteria’s Response to Antibiotics, Carbon (2022), 199: 444-452, doi.org/10.1016/j.carbon.2022.08.025.