A fast, ultrasensitive SERS immunoassay to detect SARS-CoV-2 in saliva.
Anal Chim Acta
; 1229: 340290, 2022 Oct 09.
Article
in English
| MEDLINE | ID: covidwho-1995928
ABSTRACT
The COVID-19 pandemic has emphasized the need for accurate, rapid, point-of-care diagnostics to control disease transmission. We have developed a simple, ultrasensitive single-particle surface-enhanced Raman spectroscopy (SERS) immunoassay to detect the SARS-CoV-2 spike protein in saliva. This assay relies on the use of single chain Fv (scFv) recombinant antibody expressed in E. coli to bind the SARS-CoV-2 spike protein. Recombinant scFv labeled with a SERS-active dye in solution is mixed with unlabeled scFv conjugated to gold-coated magnetic nanoparticles and a sample to be tested. In the presence of the SARS-CoV-2 spike protein, immunocomplexes form and concentrate the labeled scFv close to the gold surface of the nanoparticles, causing an increased SERS signal. The assay detects inactivated SARS-CoV-2 virus and spike protein in saliva at concentrations of 1.94 × 103 genomes mL-1 and 4.7 fg mL-1, respectively, making this direct detection antigen test only 2-3 times less sensitive than some qRT-PCR tests. All tested SARS-CoV-2 spike proteins, including those from alpha, beta, gamma, delta, and omicron variants, were detected without recognition of the closely related SARS and MERS spike proteins. This 30 min, no-wash assay requires only mixing, a magnetic separation step, and signal measurements using a hand-held, battery-powered Raman spectrometer, making this assay ideal for ultrasensitive detection of the SARS-CoV-2 virus at the point-of-care.
Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Single-Chain Antibodies
/
COVID-19
Type of study:
Diagnostic study
Topics:
Variants
Limits:
Humans
Language:
English
Journal:
Anal Chim Acta
Year:
2022
Document Type:
Article
Affiliation country:
J.aca.2022.340290
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