A team of researchers has found a more accurate way of testing for infectious diseases by harnessing the potential of composite polymer particles decorated with gold nanoparticles.
(Photo: Wikimedia Commons/ IAEA Imagebank)
Need for Highly Sensitive Immunoassay
During the onset of COVID-19, experts realized the need for fast and reliable testing of infectious diseases in large numbers. The pandemic also exposed the shortcomings of existing diagnostic methods used in various health institutions.
Influenza is another respiratory viral infection that proliferates rapidly because of its contagious nature, having the ability to cause acute respiratory problems. It poses a public health hazard that can lead to infections of epidemic proportions, affecting human and animal populations severely.
Conventional testing methods involve antigen-antibody reactions. These involve absorptions, fluorescence, or color particle probes attached to antibodies. When the virus sticks to the antibodies, the probes detect and visualize the presence of the virus.
The commonly used techniques for detecting influenza virus are enzyme-linked immunoadsorption assay (ELISA) and polymerase chain reaction (PCR). While these techniques are reliable and sensitive, they are expensive and require qualified personnel.
Rapid and selective methods that can help detect and diagnose influenza viruses can help prevent a possible new pandemic. For instance, biosensors are highly sensitive and can be a faster, simpler, and cheaper method for rapid identification of influenza virus. The use of color nanoparticles, particularly, is known for its excellent visuality and simplicity in implementing little scientific equipment for conducting lateral flow tests.
Improved Immunoassay System
Gold nanoparticles (AU-NP) are among the most widely used probes in immunoassay tests due to their high chemical stability and unique plasmon absorption. They exhibit extreme versatility, as their colors fluctuate according to size and shape. In addition, the surface of gold nanoparticles can be modified using thiol compounds.
Conventional testing methods that use gold nanoparticles usually have to amplify their optical density to allow scientists to measure the strength of the signal created by the interaction between antibodies and the target substance. This can be done by adding more gold nanoparticles. However, these materials are tiny and must be in considerable amounts to achieve a strong signal for accurate detection.
Addressing this challenge has been the goal of experts from Tohoku University. Led by Hiroshi Yabu, the research team developed a new method known as self-organized precipitation (SORP). SORP works by dissolving polymers into organic solvents before adding a liquid that does not dissolve the polymers as well as water does. Polymers assemble to form tiny particles after evaporation after removing the original organic solvent.
After using gold nanoparticle decorated polymers assembled by SOFP, the research team set out to see how effective they would be in detecting the influenza virus. They also wanted to know if they offered improved sensitivity in detecting antigen-antibody reactions.
The new method resulted in a higher optical density than the original gold nanoparticles and GNDPs decorated with smaller gold nanoparticles. The details of the study are further discussed in the paper "Gold Nanoparticle-Decorated Polymer Particles for High-Optical-Density Immunoassay Probes."
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