Nanodiamond quantum sensors are a promising new avenue for virus mRNA detection
A novel quantum sensor based on nanodiamonds may better detect the presence of viruses that cause diseases, such as the SARS-CoV-2 virus responsible for the COVID-19 pandemic.
Reverse transcriptase quantitative polymerase chain reaction (RT-PCR) is the current gold-standard diagnostic technique for virus detection; however, the method suffers from the need for trained personnel, special equipment, and a high false negative rate. Thus, alternative ways to detect virus RNA that overcome the limitations of molecular-based techniques are vital. Mohammad Kohandel, associate professor of applied mathematics, has been exploring the use of NV centers in nanodiamonds for this application.
NV centers are atomic defects in nanodiamonds that can be used as quantum sensors due to their sensitivity to magnetic fields and fluorescence marker capabilities. Biological processes, such as viral RNA stimuli, can influence the magnetic environment of these NV centers. In particular, biological signals can be transduced into magnetic noise when in proximity to magnetic molecules such as gadolinium (Gd). DNA fragments of the SARS-CoV-2 virus can be connected to Gd molecules, and the DNA-Gd structure is immobilized onto a polymer-coated nanodiamond. In the presence of virus RNA, the DNA-Gd complex will detach from the nanodiamond surface, inducing a change in the NV fluorescence that can be optically detected.
The research team developed a theoretical model to describe the change in magnetic properties of the NV center in a nanodiamond when in the presence of a SARS-CoV-2 virus and to evaluate the performance of the hypothetical sensor. According to the simulations, the proposed sensor can quickly detect a few hundred RNA copies with a false negative rate of less than 1%, considerably smaller than RT-PCR.
Moving from the theoretical stage, the team is now making advancements in developing a prototype sensor. Different ratios of DNA were immobilized on a polymer-coated nanodiamond. A dye was attached to the nanodiamonds, which allowed the RNA coupling and DNA detachment to be confirmed by measuring the fluorescence response energy transfer. Based on the measured fluorescence, the best ratio of DNA/ND for quantum sensing purposes could be identified. The next step will be to replace the dye with the Gd complex and measure the relaxation time. If this research shows commercial promise, it would have significant implications for detecting SARS-CoV-2. Further, it could advance the detection of other virus RNA, such as HIV and MERS, and accurately estimate future epidemic trajectories.
“The proposed quantum sensor based on nanodiamond NV centers could offer a fast, sensitive, and specific method for detecting the SARS-CoV-2 virus. Furthermore, this technology could have broader applications beyond SARS-CoV-2 detection. The NV-based sensor could also detect other viruses or biomolecules, with potential applications in medical diagnostics and biological research,” says Kohandel.
To learn more about the nanodiamond sensors developed at TQT, please see the following publication:
SARS-CoV-2 Quantum Sensor Based on Nitrogen-Vacancy Centers in Diamond, co-authored by Changhao Li, Rouhollah Soleyman, Mohammad Kohandel, and Paola Cappellaro.
Poster authors: Nafiseh Moghimi, Changhao Li, Paola Cappellaro, Mohammad Kohandel
This research was undertaken thanks in part to funding from the Canada First Research Excellence Fund.