Molecularly Imprinted Heavy Metal-free Quantum Dots as Fluorescent Probes for Rapid and Accurate Detection of Viruses

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Recently, the risks from new viral infections have been made evident by emerging viruses such as SARS-COV-2, Zika virus, monkeypox and new strains of influenza. Viral infections need to be detected early and accurately to allow appropriate treatment and prevent serious health complications. Current tests such as real-time polymerase chain reaction takes a long time (~1-2 days), are expensive (~£42 to the consumer) and require highly skilled personnel. Antigen tests (such as Covid-19 lateral flow tests) offer rapid (15-30 minutes) and portable analysis; however, they have a much lower level of sensitivity that may not be sufficient for some applications. The aim of this project is to develop a device that is sufficiently rapid and accurate enough for health professionals to diagnose viral diseases and give patients the most appropriate treatment and/or isolate them as quickly as possible if appropriate. In this proposal, fluorescent probes composed of semiconductor quantum dot (QD) nanocrystals with molecularly imprinted polymers (MIP) will be developed to detect viral samples in saliva. We aim to achieve this goal by exploiting the QDs' unique properties: monodispersity in solution, high surface area-to-volume ratio, stable fluorescence for binding measurements, high fluorescence quantum yield (90-100%), and size and shape-dependent properties. We will synthesize non-toxic QDs that are free from cadmium, and modify their surface to make them water-soluble, compact and stable. We will link them to MIPs that bind specifically to the viral particles. MIPs are often referred to as "plastic" antibodies and can bind strongly and stably to their targets. Once the viral particles come into contact with the QDs-MIPs, they will bind to the MIP, which will result in the QDs translating the binding interaction by generating a unique fluorescence signal for the detected virus. These QDs will be ideal for platforms such as paper strips and lateral flow devices. Our aim is to use them in a prototype microfluidic paper analytic device. This will involve creating microfluidic channels on the paper device and binding the QDs-MIP probes onto the paper surface to allow the virus to be detected fluorescently via the naked eye. The versatility and agility of the proposed concept will ensure that the sensor can be modified quickly to address any potential future mutations or new outbreaks caused by other infectious pathogens.