Scientists Develop Low-Cost Chip to Detect Presence and Quantity of COVID-19 Antibodies

Robust and widespread antibody testing has emerged as a key strategy in the fight against SARS-CoV-2, the virus responsible for the COVID-19 pandemic. However current testing methods are too inaccurate or too expensive to be feasible on a global scale. But now, scientists at the Okinawa Institute of Science and Technology Graduate University (OIST) have developed a rapid, reliable and low-cost antibody test.

The device, described in a proof-of-concept study published this week in Biosensors and Bioelectronics, uses portable lab-on-a-chip technology to accurately measure the concentration of antibodies present in diluted blood plasma.

Antibodies are proteins produced by the immune system to neutralize the virus. Research has found that COVID-19 antibodies are present in the later stages of infection and can linger in the blood after the infection has cleared, allowing previously infected individuals to be identified. Antibody tests are thus an important means of determining the full spread of the coronavirus - information that is crucial to guide public health policies.

And yet many nations have so far failed to employ large-scale antibody testing.

"Many existing platforms for antibody tests are accurate and reliable, but they are costly and need to be carried out in a lab by trained operators. This means that it can take hours, or even days, to obtain results," said Dr. Riccardo Funari, first author and postdoctoral researcher in the Micro/Bio/Nanofluidics Unit at OIST. "Other tests are easier to use, portable and rapid, but are not sufficiently accurate, which hampers testing efforts."

The researchers avoided this trade-off between accuracy and accessibility by developing an alternative antibody testing platform that combines a powerful light-sensing technology with a microfluidic chip. The chip provides results within 30 minutes and is highly sensitive, detecting even the lowest clinically-relevant antibody concentration. Each chip is cheap to manufacture and negates the need for a lab or trained operators, increasing the feasibility of nation-wide testing.

And there's another distinctive advantage of this newly developed platform. "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. In other words, it's quantitative," said Professor Amy Shen, who leads the Micro/Bio/Nanofluidics Unit. "This greatly expands its potential applications, from treating COVID-19 to use in developing vaccines."

Illuminating the antibodies

The antibody testing platform consists of a microfluidic chip which is integrated with a fiber optic light probe. The chip itself is made from a gold-covered glass slide with an embedded microfluidic channel. Using an electric voltage, the team fabricated tens of thousands of tiny spiky gold structures, each one smaller than the wavelength of light, on a glass slide.

The researchers then modified these gold nanospikes by attaching a fragment of the SARS-CoV-2 spike protein. This protein is crucial for helping the coronavirus infect cells and causes a strong reaction from an infected person's immune system.

In this proof-of concept study, the scientists demonstrated the principle behind how the test detects antibodies by using artificial human plasma sample spiked with COVID-19 antibodies that are specific to the spike protein.

Using a syringe pump, the sample is drawn through the chip. As the plasma flows past the protein-coated gold nanospikes, the antibodies bind to the spike protein fragments. This binding event is then detected by the fiber optic light probe.

"The detection principle is simple but powerful," said Dr. Funari. He explained that is it based on the unique behavior of electrons on the surface of the gold nanospikes, which oscillate together when hit by light. These resonating electrons are highly sensitive to changes in the surrounding environment, such as the binding of antibodies, which causes a shift in the wavelength of light absorbed by the nanospikes.

"The more antibodies that bind, the larger the shift in the wavelength of the absorbed light," added Dr. Funari. "The fiber optic probe is connected to a light detector which measures this shift. Using that information, we can determine the concentration of antibodies within the plasma sample."

A bright future

The large-scale roll-out of a quantitative test could greatly impact how COVID-19 is treated.

For example, quantitative tests could help doctors track how effectively a patient's immune system is fighting the virus. It could also be used to help identify suitable donors for a promising experimental treatment, called plasma transfusion therapy, where a recovered patient's antibody-rich blood is donated to currently infected patients to help them fight the virus.

Being able to measure the level of immune response can also aid vaccine development, allowing researchers to determine how effectively a trial vaccine triggers the immune system.

However, the researchers emphasized that the device is still undergoing active development. The unit aims to reduce the chip size to cut manufacturing costs and is also working on improving the reliability of the test.

"We have shown that the device works to detect different concentrations of the spike protein antibody in artificial human plasma samples. We now want to expand the test so that the chip can detect multiple different antibodies at the same time," said Dr. Funari. "Once the device is optimized, we plan to collaborate with local hospitals and medical institutions to perform tests on real patient samples."

Riccardo Funari, Kang-Yu Chu, Amy Q Shen.
Detection of antibodies against SARS-CoV-2 spike protein by gold nanospikes in an opto-microfluidic chip.
Biosensors and Bioelectronics, Volume 169, 2020. doi: 10.1016/j.bios.2020.112578

Most Popular Now

New AI Tool Predicts Protein-Protein Int…

Scientists from Cleveland Clinic and Cornell University have designed a publicly-available software and web database to break down barriers to identifying key protein-protein interactions to treat with medication. The computational tool...

AI for Real-Rime, Patient-Focused Insigh…

A picture may be worth a thousand words, but still... they both have a lot of work to do to catch up to BiomedGPT. Covered recently in the prestigious journal Nature...

New Research Shows Promise and Limitatio…

Published in JAMA Network Open, a collaborative team of researchers from the University of Minnesota Medical School, Stanford University, Beth Israel Deaconess Medical Center and the University of Virginia studied...

G-Cloud 14 Makes it Easier for NHS to Bu…

NHS organisations will be able to save valuable time and resource in the procurement of technologies that can make a significant difference to patient experience, in the latest iteration of...

Start-Ups will Once Again Have a Starrin…

11 - 14 November 2024, Düsseldorf, Germany. The finalists in the 16th Healthcare Innovation World Cup and the 13th MEDICA START-UP COMPETITION have advanced from around 550 candidates based in 62...

Hampshire Emergency Departments Digitise…

Emergency departments in three hospitals across Hampshire Hospitals NHS Foundation Trust have deployed Alcidion's Miya Emergency, digitising paper processes, saving clinical teams time, automating tasks, and providing trust-wide visibility of...

MEDICA HEALTH IT FORUM: Success in Maste…

11 - 14 November 2024, Düsseldorf, Germany. How can innovations help to master the great challenges and demands with which healthcare is confronted across international borders? This central question will be...

A "Chemical ChatGPT" for New M…

Researchers from the University of Bonn have trained an AI process to predict potential active ingredients with special properties. Therefore, they derived a chemical language model - a kind of...

Siemens Healthineers co-leads EU Project…

Siemens Healthineers is joining forces with more than 20 industry and public partners, including seven leading stroke hospitals, to improve stroke management for patients all over Europe. With a total...

MEDICA and COMPAMED 2024: Shining a Ligh…

11 - 14 November 2024, Düsseldorf, Germany. Christian Grosser, Director Health & Medical Technologies, is looking forward to events getting under way: "From next Monday to Thursday, we will once again...

In 10 Seconds, an AI Model Detects Cance…

Researchers have developed an AI powered model that - in 10 seconds - can determine during surgery if any part of a cancerous brain tumor that could be removed remains...

Does AI Improve Doctors' Diagnoses?

With hospitals already deploying artificial intelligence to improve patient care, a new study has found that using Chat GPT Plus does not significantly improve the accuracy of doctors' diagnoses when...