Abstract
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory coronavirus 2 (SARS-CoV-2) is still raging all over the world. Hence, the rapid and sensitive screening of the suspected population is in high demand. The nucleocapsid protein (NP) of SARS-CoV-2 has been selected as an ideal marker for viral antigen detection. This study describes a lateral flow immunoassay (LFIA) based on colloidal gold nanoparticles for rapid NP antigen detection, in which sensitivity was improved through copper deposition-induced signal amplification. The detection sensitivity of the developed LFIA for NP antigen detection (using certified reference materials) under the optimized parameters was 0.01 μg/mL and was promoted by three orders of magnitude to 10 pg/mL after copper deposition signal amplification. The LFIA coupled with the copper enhancement technique has many merits such as low cost, high efficiency, and high sensitivity. It provides an effective approach to the rapid screening, diagnosis, and monitoring of the suspected population in the COVID-19 outbreak.
Highlights
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory coronavirus 2 (SARS-CoV-2) has spread to 216 countries, and the cumulative number of confirmed cases has exceeded 200 million around the world
The developed lateral flow immunoassay (LFIA) test strips were used to detect 0–10 μg/mL nucleocapsid protein (NP) antigen to validate whether the signal was amplified by GCNP-mediated copper deposition
After 3 min, the red bands turned into black bands, and the LFIA strip for 0.01 μg/mL NP antigen detection presented a clear band on the test line, which suggests that the detection sensitivity was successfully promoted by GCNP-mediated copper deposition
Summary
The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory coronavirus 2 (SARS-CoV-2) has spread to 216 countries, and the cumulative number of confirmed cases has exceeded 200 million around the world. Rapid screening, early detection, and timely diagnosis are still the main measures to prevent and control SARS-CoV-2 transmission. Rapid antibody detection was used as the supplementary means of nucleic acid detection for COVID-19 diagnosis before 2021 [1,2,3]. Antibody detection has become meaningless for the screening of suspected populations since the beginning of vaccination against COVID-19. Nucleic acid detection is considered the gold standard, but its use is limited because of the time-consuming process, relatively high cost, and high professional and equipment requirements [4]. Direct, rapid, point-of-care viral antigen detection methods without pretreatment are highly needed, especially in countries with serious outbreaks
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