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

SARS-CoV-2是引起人类新冠肺炎的病原体，目前仍迫切需要简单、快速和可靠的方法来检测SARS-CoV-2，以减少大流行的传播，减轻其对医疗保健系统和整体社会经济状况的影响。目前的方法要么像PCR那样复杂和昂贵;要么像典型的免疫测定那样不可靠和不准确。此外，目前的大多数方法需要使用鼻咽拭子，这可能是令人不快的，需要培训并送到专业实验室进行分析，通常需要几天才能得到结果。在该项目中，将开发一种即时检测试剂盒，以便使用荧光量子点纳米颗粒（QD）实现的多重免疫测定法从唾液样本中快速简便地检测SARS-CoV-2或未来的流感流行。与遭受高不准确性的常规免疫测定或遭受复杂性、高成本和结果延迟的PCR方法不同，QD的亮度和多路复用能力将提供可靠的检测能力，其可以在没有预先训练的情况下以较低的成本快速进行。在该项目中，Nanoco Technologies有限公司开发的用于生物医学应用的新型无毒量子点（VIVODOTS（TM）纳米颗粒）将与针对病毒中两种或多种结构蛋白的靶向抗体相关联。当带有不同颜色代码的功能化量子点与唾液样本中的SARS-CoV-2病毒颗粒接触时，它们将与病毒结合，并在蓝色光源下产生独特的光谱发射。这种独特的光谱发射只有在实际病毒存在的情况下才会发生。与传统荧光染料和胶体金相比，这种应用中的QD具有许多优势，包括来自单个激发源的明亮和编码发射以及低反射干扰，这对于基于表面检测的平台（如横向流动棒或纸条）是理想的。这种诊断试剂盒的拟议概念是通用和灵活的，因为它可以快速修改，以应对潜在的未来突变或其他类型的传染性病原体引起的新疫情。

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.