Quantum diagnostics
Traditional rapid antigen tests (commonly known as lateral flow tests) often use gold nanoparticles, other light-absorbing nanoparticles such as selenium, or polymer beads to indicate the presence of viral proteins. However, their sensitivity is limited by nanoparticle signal and background interference, especially when viral loads are lower, and they often miss early-stage infections.
Developed by a team at University College London, the new test harnesses the unique quantum properties of nitrogen-vacancy (NV) centres in fluorescent nanodiamonds. These atomic-scale defects allow the diamond to act as a quantum sensor, where the spin state can be manipulated and read out optically. By driving transitions between spin states and modulating fluorescence, the system can ‘lock in’ signals from the nanodiamond probes while suppressing background noise — a technique known as spin‑enhanced detection.
High accuracy and earlier detection
When compared to a matched gold nanoparticle lateral flow assay using the same reagents, the nanodiamond test demonstrated an approximately 1,000 fold improvement in analytic sensitivity, meaning it can detect much lower concentrations of viral antigen.
In this clinical study of 103 patient swab samples, the quantum-enhanced test achieved 95.1% sensitivity at high viral loads and 86.8% sensitivity across all viral loads, and 100% specificity compared to the gold-standard PCR tests.
Combining these results with viral load data from other trials, the scientists project that the test could detect infections an average of two days earlier than conventional lateral flow tests and identify 2.2 times more cases on the first day of symptoms — a critical window for reducing transmission.
Looking forward
Researchers are now focusing on making this test suitable for bedside use by developing a portable fluorescent reader. This could make the technology especially impactful in resource-limited settings, such as GP surgeries and pharmacies.
Beyond COVID-19, the platform could be adapted for use with other diseases, both communicable and non-communicable, offering a new and powerful tool for early, accurate detection.
More information
- Q-BIOMED (UK Quantum Biomedical Sensing Research Hub) is the UK's first quantum hub for biomedicine. It aims to deliver a step change in earlier disease diagnosis and treatment for diseases, including cancer and Alzheimer's disease.
- https://www.qbiomed.org/
Read the full paper in Nature Communications
Read the full paper
