Quantum Optical Immunoassay: Upconversion Nanoparticle-based Neutralizing Assay for COVID-19
In a viral pandemic, a few important tests are required for successful containment of the virus and reduction in severity of the infection. Among those tests, a test for the neutralizing ability of an antibody is crucial for assessment of population immunity gained through vaccination, and to test t...
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Main Authors | , , , , , , , , , |
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Format | Journal Article |
Language | English |
Published |
13.10.2021
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Subjects | |
Online Access | Get full text |
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Summary: | In a viral pandemic, a few important tests are required for successful
containment of the virus and reduction in severity of the infection. Among
those tests, a test for the neutralizing ability of an antibody is crucial for
assessment of population immunity gained through vaccination, and to test
therapeutic value of antibodies made to counter the infections. Here, we report
a sensitive technique to detect the relative neutralizing strength of various
antibodies against the SARS-CoV-2 virus. We used bright, photostable,
background-free, fluorescent upconversion nanoparticles conjugated with
SARS-CoV-2 receptor binding domain as a phantom virion. A glass bottom plate
coated with angiotensin-converting enzyme 2 (ACE-2) protein imitates the target
cells. When no neutralizing IgG antibody was present in the sample, the
particles would bind to the ACE-2 with high affinity. In contrast, a
neutralizing antibody can prevent particle attachment to the ACE-2-coated
substrate. A prototype system consisting of a custom-made confocal microscope
was used to quantify particle attachment to the substrate. The sensitivity of
this assay can reach 4.0 ng/ml and the dynamic range is from 1.0 ng/ml to 3.2
{\mu}g/ml. This is to be compared to 19 ng/ml sensitivity of commercially
available kits. |
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DOI: | 10.48550/arxiv.2110.06755 |