Covid-19 update: 10 September 2020

10 Sep 2020

A round-up of this week's coronavirus-related news and countermeasures from the photonics industry.

Robust and widespread antibody testing has emerged as a key strategy in the fight against the Covid-19 pandemic. However current testing methods "are too inaccurate or too expensive to be feasible on a global scale," say scientists at the Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa, Japan, who have developed a rapid, reliable and low-cost antibody test.

The device, which combines light-sensing technology with a microfluidic chip, is 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.

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.

"Many existing platforms for antibody tests are accurate and reliable," said Dr. Riccardo Funari, first author and postdoctoral researcher in the Micro/Bio/Nanofluidics Unit at OIST. "But they are costly and need to be carried out in a lab by trained operators. 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 optical 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.

There is another distinctive advantage of this newly developed platform. "The test does not just detect whether the antibodies are present or absent — it also provides information about the quantity of antibodies produced by the immune system. It is quantitative," commented 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."

How it works

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.

Vaccine projects rely on Schott glass vials

In 2019, glass and optics giant Schott announced a $1 billion investment in its pharmaceutical packaging business to expand capacity by more than 50 percent. Now, the company has achieved a milestone, delivering vials to three out of every four Covid-19 vaccine projects undergoing phase I, II, and III testing (according to Global Data).

The company has delivered millions of glass vials to SARS-CoV-2 programs including partners of Operation Warp Speed in the U.S.

“We are proud and happy to serve leading vaccine projects and will continue to contribute our utmost to the fight against Covid-19,” said Frank Heinricht, CEO of Schott AG. The company already deploys a global validated production network with 20 plants and over 600 production lines for pharma glass and packaging and stands ready to supply the industry.

“Our $1 billion investment, which started before the pandemic to meet global demand for high quality glass packaging, allowed us to ramp up production to quickly address this unprecedented global public health challenge,” he said.

The vast majority of all Covid-19 vaccines will be stored in and applied from a borosilicate glass container – the world’s most widely used material to package vaccines. Relying on existing and proven infrastructures and materials enables the pharma industry to save time, simply because they have been processing these vials on their lines for decades.

Real-time imaging of virus attacking human cells

Using bioengineered quantum dots, scientists at the US Naval Research Laboratory have been able to image the binding process of the SARS-CoV-2 virus to human cells. "We are visualizing the binding of the spike to ACE 2 [angiotensin converting enzyme 2]," explained Kirill Gorshkov a research scientist at the National Center for Advancing Translational Sciences (NCATS) in Maryland, U.S.

The binding process is the first step in a process of viral proliferation. The "spike" is a protein on the SARS-CoV-2 virus that is widely recognized as the primary weapon of attack for mobilizing its viral DNA into a host cell.

The ACE2 receptors are human cell proteins that effectively open the door for this attack, say the researchers. Using bioengineered quantum dots, Gorshkov and Eunkeu Oh at the Naval Research Laboratory (NRL) in Washington, D.C., were able to image the binding and subsequent internalization that takes place when ACE2 and the spike protein interact.

"You can actually see that happen in real time," added Gorshkov, "That's the beauty of this assay and that's why we think it will be important for drug screening."

Gorshkov and colleagues at NCATS were already working on various imaging assays for cancers, viruses and lysosomal storage diseases, "but when coronavirus hit, we quickly had to shift gears," he said.

Prior SARS research had highlighted the importance of interactions with ACE2 in human cells for the spread of this kind of virus, and they were already able to tag these receptor proteins with a green fluorescent protein to image their movements.

With no fluorescent labeling of these viral proteins, their role in the ACE2 receptor binding and subsequent internalization, known as endocytosis, continued to play out effectively under cover of darkness to imaging.

At NRL, researchers were also keen to leverage their expertise with nanoparticles for cellular delivery and biosensing to help efforts in search of anti-Covid-19 drugs. Oh began looking into possible ways of applying the protein-nanostructure conjugation techniques she had been working with for over 15 years.

With two proteins that share a binding affinity — a quantum dot attached to one and a fluorescing nanoparticle attached to the other — binding between the two proteins will then bring the nanostructures close enough for energy transfer between them.

The resulting fluorescence quenching then allows the researchers to monitor the protein binding. "If you have any inhibitor in the middle to stop the binding, this can be used as an inhibition assay for drug screening, so we use this a lot," explained Oh. Seeing the potential application for screening antibodies against Covid-19, Oh and her team led by Mason Wolak presented their ideas to the team at NCATS, and the two institutions set straight to work to develop it further.

Seoul Viosys, a compound semiconductor solution developer, has developed an optimal module designed to sterilize 99.9% of the coronavirus in 3 seconds using Violeds, a UV LED technology, and started mass production. Alongside this, Seoul Viosys is developing a so-called “Photon Shower” product that is applied with this technology to contribute to the safety of medical staff and patients fighting the Covid-19 pandemic.

The BIO research team at Seoul Viosys has been undertaking research and development projects with in-house laboratories cultivating and sterilizing various bacteria and viruses. In April 2020, a Violeds sterilization test conducted with a research group of Korea University proved that Violeds does sterilize coronavirus.

By applying this technology, Seoul Viosys is producing Air Purifier “VAC,” which is optimally designed to sterilize filters 99.9% in 30 seconds, and Multi Sterilizer “VSM+,” which sterilizes the surface of everyday objects in 10 minutes.