Principle of Operation

At the single-cell level, relaxometry involves the use of highly sensitive quantum sensors or Nano-MRI technology to detect and measure minute changes in the magnetic environment within a cell. This allows for the observation of relaxation times that are affected by the cell’s internal conditions, such as the presence of oxidative stress, protein interactions, and other molecular processes critical to cellular health and function.

Quantum Sensing Principles

Diamond Magnetometry

Quantum Nuova achieves quantum sensing by using the crystal lattice defect in the diamond nanoparticles. The diamond is a crystal lattice of carbon atoms, and the defect is a carbon atom being replaced with a Nitrogen atom and an adjacent vacancy (NV center) (A). These nanodiamonds have the ability to fluoresce forever without any bleaching. The fluorescence behavior is dependent on the magnetic field. Due to this relation, it is possible to translate the magnetic field to an optical signal, which is dramatically easier to detect. The sensitivity of the nanodiamonds to the magnetic fields is so high that it is even possible to detect the magnetic field of a single electron. The nanodiamonds with these properties are called fluorescent nanodiamonds (FNDs).

Using a strong green laser pulse, it is possible to excite the NV centers of the fluorescent nanodiamonds from the ground state into an excited state (B). The laser is switched off for a period of time (the dark time), and the NV centers stochastically decay back into their ground state (C). Upon decaying, a photon is released. This fluorescence is an optical signal that can be detected. The rate of the fluorescence intensity decay during the relaxation from the excited state back to the ground state depends on the magnetic noise (random fluctuations in a magnetic field). It means that if there are more magnetic field sources (for example free radicals) then the fluorescence intensity decays at higher rates. T1 relaxometry is one of the magnetometry methods using this principle and measures the fluorescence intensity at the beginning of each laser pulse after different dark times. These intensities follow a decreasing exponential governed by a specific time constant called T1 (D).

Free Radical Concentration (nanomolar)

Magnetic noise in cells can arise from unpaired electrons of free radicals. The rate of the fluorescence emitted by fluorescent nanodiamonds placed in biological samples is a direct measurement of the magnetic noise, and therefore the free radical concentration, that is present in the surroundings of the NV center. 

Fluorescent nanodiamonds are very biocompatible and can be placed into a variety of biological samples, including cells, tissues and live organisms. Furthermore, their unique quantum properties, namely the fluorescence they emit when excited by green laser light, render them excellent candidates for quantum sensing applications. The colorful specs on the left image show the fluorescent nanodiamonds inside of cells.

Confocal Microscope

The laser-scanning confocal microscope employs a laser light source which navigates through an arranged pinhole and lens system, focusing sharply on targeted specimen points. The microscope scans the specimen in X and Y directions, constructing an image from the focal plane. After enhancing sharpness and stitching the 2D slices together, the result is a high-resolution, 3D image.

The confocal microscope in the Quantum Nuova is used to image the biological sample and localize the fluorescent nanodiamonds used for quantum sensing.

Quantum Nuova Specialized Functions

  • Using the quantum phenomenon of excited NV-centers inside the functionalized nanodiamonds allows us to take measurements of extremely sensitive nanoscale magnetic noise, otherwise near impossible to detect.

  • Biological samples can be placed in a cell incubator and a measurement can be seamlessly conducted. Fluorescent nanodiamonds are carefully inserted into the biological samples. This is done in a precise, noninvasive manner so the sample remains functional and intact.

  • The Quantum Nuova is a fully automated system. Set your parameters, hit 'run', automated precision focusing of lenses and sophisticated data analysis ensues. This device streamlines your investigation, allowing you to concentrate on research rather than the nuances of operation.

  • Quantum Nuova introduces an advanced particle tracking system, designed to keep up with dynamic samples. Whether observing live specimens in motion or tracking Brownian motion, our system automatically refocuses on the subject. This feature ensures continuous, clear observation without manual adjustments, offering a seamless research experience even in the most challenging conditions.

  • Quantum Nuova ensures an exceptional signal to noise ratio, significantly reducing scanning time. Selective filter sets are employed to eliminate irrelevant photons and light, alongside avalanche photon detectors that capture individual photons, ensuring no data loss. The confocal design of the device ensures minimal noise, increasing the signal to noise ratio. The software is designed to highlight only pertinent results, effectively minimizing noise. Together, these innovations guarantee clear, precise imaging, allowing for rapid, efficient data acquisition and analysis.

Quantum Sensing Experiment

A relaxometry experiment starts with polarizing the spins of NV centres in the diamond lattice, using a strong laser pulse from the excitation source. The laser is switched off and the NV centres in the sample stochastically decay into the equilibrium mix of different magnetic states. The polarized configuration exhibits stronger fluorescence than the equilibrium state, allowing one to optically monitor this transition and determine its rate in the detection stage.