The quantum sensing abilities of nanodiamonds can be used to improve the sensitivity of paper-based diagnostic tests, potentially allowing for earlier detection of diseases such as HIV, according to a study led by UCL researchers in the i-sense McKendry group.

Paper-based lateral flow tests work the same way as a pregnancy test in that a strip of paper is soaked in a fluid sample and a change in colour—or fluorescent signal—indicates a positive result and the detection of virus proteins or DNA. They are widely used to detect viruses ranging from HIV to SARS-CoV-2 (lateral flow tests for Covid-19 are currently being piloted across England) and can provide a rapid diagnosis, as the results do not have to be processed in a lab.

The new research, published in Nature, found that low-cost nanodiamonds could be used to signal the presence of an HIV disease marker with a sensitivity many thousands of times greater than the gold nanoparticles widely used in these tests.

This greater sensitivity allows lower viral loads to be detected, meaning the test could pick up lower levels of disease or detect the disease at an earlier stage, which is crucial for reducing transmission risk of infected individuals and for effective treatment of diseases such as HIV.

The research team are working on adapting the new technology to test for COVID-19 and other diseases over the coming months. A key next step is to develop a hand-held device that can “read” the results, as the technique was demonstrated using a microscope in a laboratory. Further clinical evaluation studies are also planned.

Lead author Professor Rachel McKendry, Professor of Biomedical Nanotechnology at UCL and Director of i-sense EPSRC IRC, said: “Our proof-of-concept study shows how quantum technologies can be used to detect ultralow levels of virus in a patient sample, enabling much earlier diagnosis.

“We have focused on the detection of HIV, but our approach is very flexible and can be easily adapted to other diseases and biomarker types. We are working on adapting our approach to COVID-19. We believe that this transformative new technology will benefit patients and protect populations from infectious diseases.”

The researchers made use of the quantum properties of nanodiamonds manufactured with a precise imperfection. This defect in the highly regular structure of a diamond creates what is called a nitrogen-vacancy (NV) centre. NV centres have many potential applications, from fluorescent biomarking for use in ultra-sensitive imaging to information processing qubits in quantum computing.

Image Credit : Ella Maru Studio/UCL

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Thanks to Heinz V. Hoenen.  Follow him on twitter: @HeinzVHoenen