Sichuan University Has Developed A Rapid Visual Nucleic Acid Detection Platform

 Nucleic acid tests (NATs) have an indispensable position in the field of disease diagnosis and surveillance, and they have played an irreplaceable role in this outbreak. However, to carry out nucleic acid testing, it is generally necessary to have a professional molecular laboratory and supporting testing equipment. However, under the current situation of normal epidemic prevention and control, the expansion of nucleic acid detection scope and other measures need more convenient, shorter detection time, lower cost, higher accuracy and safety of nucleic acid detection methods.

Recently, Feng Li and his research group of Sichuan University and Wu Peng research group have worked together to report a method of detecting and quantifying chromogenic nucleic acid using DNA intercalating dyes (DIDS), which is called fast photo activated substrate (flash). Then, through integration with PCR, a new visual platform for rapid detection of nucleic acid, flash PCR, has been designed.

Previous studies have shown that dyes can also produce singlet oxygen after they are embedded in DNA, thereby converting traditional fluorescent DIDs into type-II photosensitizers. Based on this, the researchers have developed a fast light-activated substrate color development technology (FLASH), which can quickly photo-oxidize the color development substrate and produce a colorimetric signal readout.

Using this principle, the researchers used SYBR Green I (SG-I) as the photosensitizer and 3,3,5,5-tetramethylbenzidine (TMB) as the chromogenic substrate to directly mix the PCR amplicon with these two compounds. Then converted DID-based fluorescent PCR assays into colorimetric FLASH PCR. To demonstrate the practical applicability of FLASH PCR to POC diagnosis, they also fabricated two readout platforms, including a portable electronic FLASH reader and a paper-based FLASH strip. Using the FLASH reader, we were able to detect as low as 60 copies of DNA standards, a limit of detection (LOD) comparable with commercial quantitative PCR. The FLASH strip further enables the reader-free detection of PCR amplicons by converting the colorimetric signal into the visual measurement of distance as a readout.

In short, FLASH PCR has the simplicity and flexibility. In the future, FLASH technology will achieve rapid, robust and sensitive nucleic acid detection in a decentralized environment, thereby providing real and practical help for immediate diagnosis and disease diagnosis in regions with limited resources.

References: Tianyu Dong, Hayam Mansour, Hao Hu, Guan A. Wang, Colton JF Watson, Michael Yousef, Gabriela Matamoros, et al. Colorimetric Polymerase Chain Reaction Enabled by a Fast Light-Activated Substrate Chromogenic Detection Platform. Anal. Chem. , 2020, 92, 6456–6461, DOI: 10.1021/acs.analchem.9b05591