Single-Molecule Detection of SARS-CoV-2 by Plasmonic Sensing of Isothermally Amplified Nucleic Acids

Abstract

Single-molecule detection of pathogens such as SARS-CoV-2 is key to combat infectious diseases outbreak and pandemic. Currently colorimetric sensing with loop-mediated isothermal amplification (LAMP) provides simple readouts but suffers from intrinsic non-template amplification. Herein, we report that plasmonic sensing of LAMP amplicons via DNA hybridization allows highly specific and single-molecule detection of SARS-CoV-2 RNA. Our work has two important advances. First, we develop gold and silver alloy (Au-Ag) nanoshells as plasmonic sensors that have 4-times stronger extinction in the visible wavelengths and give 20-times lower detection limit for oligonucleotides than Au nanoparticles. Second, we demonstrate that the diagnostic method allows cutting the complex LAMP amplicons into short repeats that are amendable for hybridization with oligonucleotide-functionalized nanoshells. This additional sequence identification eliminates the contamination from non-template amplification. The detection method is a simple and single-molecule diagnostic platform for virus testing at its early representation.

Yersinia pestis and Plague: Some Knowns and Unknowns

“…Although we have comprehensive immunologic and nucleic acid-based techniques for plague diagnosis in the laboratory, we still lack rapid, sensitive, and specific point-of-care testing for on-site detection and ultrasensitive assays in the laboratory for detecting traces of Y. pestis. Single molecule detection methods are being developed [228,229]. A microsphere labeled with carbon dots (CDs) and a colloidal gold-based lateral f low immunochromatographic assay combined with CRISPR/Cas-based nucleic detection for highly specific and sensitive detection of bacterial pathogens has been developed [230,231].…”