Heavy Metal-Free Quantum Dot Testing Kit for the Accurate and Rapid Visual Detection of SARS-CoV-2 from Saliva Samples

Simple, fast and reliable methods for the detection of SARS-CoV-2, the pathogen that causes Covid-19 in humans are still badly needed to reduce the spread of the pandemic and mitigate its impact on health care systems and on the overall socioeconomic status. Current methods are either complicated and expensive as in the case of PCR; or non reliable and inaccurate as in the case of typical immunoassays. Also, most of the current methods require the use of nasopharyngeal swabs, which can be unpleasant, require training and sending to a specialist laboratory for analysis, often taking several days before results. In this project a point-of-care testing kit will be developed to enable the rapid and easy detection of SARS-CoV-2 or future flu epidemics from saliva samples using a multiplexed immunoassay enabled by fluorescent quantum dot nanoparticles (QDs). Unlike conventional immunoassays that suffer from high inaccuracy, or the PCR methods that suffer from complexity, high cost and result delays, the brightness and multiplexing ability of QDs will provide a reliable detection capabilities that can be performed quickly without prior training and at a lower cost. In this project, a new type of non-toxic QDs (VIVODOTS(tm) nanoparticles) that was developed by Nanoco Technologies, Ltd for biomedical applications will be linked to targeting antibodies against two or more structural proteins in the virus. Once the functionalized QDs with various colour codes come in contact with the SARS-CoV-2 viral particles in the saliva sample, they will bind to the virus and generate unique spectral emission under blue light source. The unique spectral emission will occur only in the presence of the actual virus. The QDs in this type of application offer a number of advantages over conventional fluorescent dyes and colloidal gold, including bright and coded emissions from a single excitation source and low reflectance interference, which is ideal for platforms based on surface detection like lateral flow sticks or paper strips. The proposed concept of this diagnostic kit is versatile and agile as it can be modified quickly to respond to potential future mutations or to new outbreaks caused by other types of contagious pathogens.