Quantum Sensing of Free Radicals in Primary Human Dendritic Cells

Abstract

Free radicals are crucial indicators for stress and appear in all kinds of pathogenic conditions, including cancer, cardiovascular diseases, and infection. However, they are difficult to detect due to their reactivity and low abundance. We use relaxometry for the detection of radicals with subcellular resolution. This method is based on a fluorescent defect in a diamond, which changes its optical properties on the basis of the magnetic surroundings. This technique allows nanoscale MRI with unprecedented sensitivity and spatial resolution. Recently, this technique was used inside living cells from a cell line. Cell lines differ in terms of endocytic capability and radical production from primary cells derived from patients. Here we provide the first measurements of phagocytic radical production by the NADPH oxidase (NOX2) in primary dendritic cells from healthy donors. The radical production of these cells differs greatly between donors. We investigated the cell response to stimulation or inhibition.

Recent Developments of Nanodiamond Quantum Sensors for Biological Applications

“…[ 120 , 121 ] However, the detection of radicals with NDs was not only realized until 2020. [ 13 , 14 , 122 , 123 ] In the work from the group of P. Cigler, [ 13 ] as illustrated in Figure 6 a,b,c , the NDs were coated with a poly(glycerol) shell containing covalently bound stable TEMPO radicals coupled with NV⁻ centers. The TEMPO radicals in the nanosensor are gradually reduced by ascorbates until they are completely removed.…”

Diamond surface engineering for molecular sensing with nitrogen—vacancy centers

“…For example, relaxometry measurements that do not require microwave irradiation can be used to characterize changes in T 1 caused by e.g., proximal paramagnetic species, 232 redox reactions, 233 changes in pH, 234 and radical production. [235][236][237] Nevertheless, for highly sensitive techniques such as NMR spectroscopy, these sources of magnetic noise are often undesirable. Consequently, the optimization of diamond surface chemistries is a critical step toward realizing the full potential of NV sensing for dilute assemblies of external spins.…”

Insight into a Fenton-like Reaction Using Nanodiamond Based Relaxometry

“…So far, diamond magnetometry has been used for nanoscale magnetic resonance measurements and successfully applied to measure the magnetic field from nanoparticles [ 10 ], 2D materials, domain walls in magnetic structures [ 11 ], gadolinium ions in solution [ 12 ], spin-labeled molecules, proteins with metallic parts [ 13 ] or even slices of cells [ 14 ]. Recently, the first measurements in living cells have been demonstrated [ 15 , 16 , 17 , 18 , 19 ]. Here, we use a specific form of diamond magnetometry called T1 or relaxometry measurements [ 20 ].…”