Scientists use holographic imaging to detect viruses and ant
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A team of New York University scientists has developed a method using holographic imaging to detect both viruses and antibodies. The breakthrough has the potential to aid in medical diagnoses and, specifically, those related to the COVID-19 pandemic.

"Our approach is based on physical principles that have not previously been used for diagnostic testing," explains David Grier, a professor of physics at NYU and one of the researchers on the project, which is reported in the journal Soft Matter. "We can detect antibodies and viruses by literally watching them stick to specially prepared test beads."

If fully realized, this proposed test could be done in under 30 minutes, is highly accurate, and can be performed by minimally trained personnel. Moreover, the method can test for either the virus (current infection) or antibodies (immunity). The size of a probe bead reported by holographic particle characterization depends on the proportion of the surface area covered by bound target molecules and so can be used as an assay for molecular binding. We validate this technique by measuring the kinetics of irreversible binding for the antibodies immunoglobulin G (IgG) and immunoglobulin M (IgM) as they attach to micrometer-diameter colloidal beads coated with protein A. These measurements yield the antibodies’ binding rates and can be inverted to obtain the concentration of antibodies in solution. Holographic molecular binding assays therefore can be used to perform fast quantitative immunoassays that are complementary to conventional serological tests.

The scientists say that this capability can be used to develop libraries of test beads that may be combined into test kits for mixing with patient samples. This will support doctors in distinguishing among possible diagnoses, speeding patients' treatment, reducing the risk of misdiagnosis, and cutting the cost of healthcare.