Scientists develop low-cost chip for detecting presence and quantity of COVID-19 antibodies

Researchers in the Micro/Bio/Nanofluidics Unit, led by Professor Amy Shen, have developed a rapid, reliable and low-cost COVID-19 antibody test.

Antibodies are proteins produced by the immune system to neutralize foreign entities such as SARS-CoV-2, the coronavirus responsible for the COVID-19 pandemic. Testing for these antibodies is a key strategy in understanding and controlling the spread of the virus, but current methods rely on tests that are too inaccurate or too expensive to be feasible on a nation-wide scale.

The antibody testing platform newly developed at OIST consists of a microfluidic chip integrated with a fiber optic light probe. Using powerful light-sensing technology, the device is able to rapidly and accurately detect the quantity of antibodies present in a sample of diluted blood plasma that is pumped through the chip. The microfluidic chips can be cheaply manufactured and negate the need for trained operators in a laboratory setting, increasing the accessibility of the test.

The quantitative nature of the test is another distinct advantage. Prof. Shen explained, “The test doesn’t just detect whether the antibodies are present or absent – it also provides information about the quantity of antibodies produced by the immune system. This greatly expands its potential applications, from treating COVID-19 to use in developing vaccines.”

The current version of the chip detects the quantity of antibodies that bind to a specific SARS-CoV-2 protein called the spike protein. This protein is crucial for helping the coronavirus infect cells and causes a strong reaction from an infected person’s immune system.

The chip contains a layer of gold nanostructures, to which fragments of the spike protein are attached. As the plasma passes through the chip, antibodies that are specific to the spike protein bind. The binding event changes which wavelengths of light are absorbed by the nanospikes, due to the unique behavior of electrons on the surface of the gold nanostructures.

“The detection principle is simple but powerful,” said Dr. Riccardo Funari, a postdoctoral researcher in Prof. Shen’s Unit. “The more antibodies that bind, the larger the shift in the wavelength of the absorbed light. Using that information, we can determine the concentration of antibodies within the blood plasma sample.”

The researchers are now working on expanding the test so that the chip can detect different antibodies at the same time.

“Once the device is optimized, we plan to collaborate with local hospitals and medical institutions to perform tests on real patient samples,” said Dr. Funari.

The device was recently described in a study published in Biosensors and Bioelectronics. Click here to find out more about the chip and how it works.