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Covid-19 update: 08 October 2020

08 Oct 2020

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

One feature of the Covid-19 virus that makes it so difficult to contain is that it can be easily spread to others by a person who has yet to show any signs of infection. The asymptomatic carrier of the virus might feel perfectly well and take the virus with them to work, to the home of a family member, or to public gatherings.

A crucial part of the global effort to stem the spread of the pandemic, therefore, is the development of tests that can rapidly identify infections in people who are not yet symptomatic. Now, researchers at Caltech have developed a new type of multiplexed test with a low-cost sensor that may enable independent, at-home diagnosis of a Covid infection by rapid analysis of small volumes of saliva or blood.

The research was conducted in the lab of Wei Gao, assistant professor in the Andrew & Peggy Cherng Department of Medical Engineering. Previously, Gao and his team have developed wireless sensors that can monitor conditions such as gout, as well as stress levels, through the detection of extremely low levels of specific compounds in blood, saliva, or sweat.

Gao's sensors are made of graphene. A plastic sheet etched with a laser generates a 3D graphene structure with tiny pores. Those pores create a large amount of surface area on the sensor, which makes it sensitive enough to detect, with high accuracy, compounds that are only present in very small amounts. In this sensor, the graphene structures are coupled with antibodies, immune system molecules that are sensitive to specific proteins, like those on the surface of a Covid virus, for example.

The new version of the sensor, which Gao has named SARS-CoV-2 RapidPlex, contains antibodies and proteins that allow it to detect the presence of the virus itself; antibodies created by the body to fight the virus; and chemical markers of inflammation, which indicate the severity of the Covid-19 infection.

"This is the only telemedicine platform I've seen that can give information about the infection in three types of data with a single sensor," said Gao. "In as little as a few minutes, we can simultaneously check these levels, so we get a full picture about the infection, including early infection, immunity, and severity."

So far, the device has been tested only in the lab with a small number of blood and saliva samples obtained for medical research purposes from individuals who have tested positive or negative for Covid-19. Though preliminary results indicate that the sensor is highly accurate, a larger-scale test with real-world patients rather than laboratory samples must be performed, said Gao, to definitively determine its accuracy.

With the pilot study now completed, Gao next plans to test how long the sensors last with regular use, and to begin testing them with hospitalized Covid-19 patients. Following in-hospital testing, he would like to study the suitability of the tests for in-home use. Following testing, the device will need to receive regulatory approval before it is available for widespread use at home.

The paper describing the research, titled, SARS-CoV-2 RapidPlex: A Graphene-based Multiplexed Telemedicine Platform for Rapid and Low-Cost Covid-19 Diagnosis and Monitoring has been published online and will appear in the December issue of the journal Matter.

Improving optical measurement of aerosols

Proveris Scientific, a provider of instrumentation focused on the science of aerosol and spray products, has announced a research collaboration with The University of Sydney and Macquarie University, both Australia, to develop new systems to improve the measurement of pharmaceutical aerosols.

The project aims to develop an optical tomography technology capable of direct and real-time measurement of the surface area of airborne particles.

By coupling laser diagnostic tools with physiological models and in vitro characterization techniques, the researchers will investigate the relationships between the surface area of an aerosol and its dissolution when delivered to a target. The outcomes will enable aerosol device manufacturers to develop more advanced and highly specific products.

The approach, originally conceived by Proveris, is to significantly enhance the characterization of inhaled aerosols with respect to their potential bioavailability or toxicity. Dino Farina, from Proveris, Professor Hak-Kim Chan, from Sydney’s School of Pharmacy, and Dr. Agisilaos Kourmatzis, from Sydney’s School of Aerospace, Mechanical, & Mechatronic Engineering, collaborated on a research plan.

The multi-year research collaboration is funded by the Australian Research Council Linkage Program, which promotes national and international research partnerships. Dr. Shaokoon Cheng, Chief Investigator, of Macquarie University, is a collaborator on the project.

Dino Farina said, “Significantly enhancing comparative in vivo results utilizing predictive in-vitro technologies for inhaled aerosol characterization is a critical need in providing safer and more efficacious drugs to patients worldwide. Having the ability to work with these three top researchers on this new technology is exciting and will result in technology that will advance inhalation science and help make it a more effective route for drug delivery.”

NIST boost for spotting Covid-19 virus with enhanced fluorescent marker detection method

A multidisciplinary research team at the US National Institute of Standards and Technology (NIST) has developed a way to increase the sensitivity of the primary test used to detect the SARS-CoV-2 virus. Applying their findings to computerized test equipment could improve our ability to identify people who are infected but do not exhibit symptoms.

The team’s results, published in Analytical and Bioanalytical Chemistry, describe a mathematical technique for perceiving comparatively faint signals in diagnostic test data that indicate the presence of the virus. These signals can escape detection when the number of viral particles found in a patient’s nasal swab test sample is low. The team’s method helps a modest signal stand out more clearly.

“Applying our technique could make the swab test up to 10 times more sensitive,” said Paul Patrone, a NIST physicist and a co-author on the team’s paper. “It could potentially spot more people who are carrying the virus but whose viral count is too low for the current test to give a positive result.”

The researchers’ findings prove that the data from a positive test, when expressed in graphical form, takes on a recognizable shape that is always the same. Just as a fingerprint identifies a person, the shape is unique to this type of test. Only the shape’s position, and importantly, its size, differ when graphed, varying with the quantity of viral particles that exist in the sample.

While it was known previously that the shape’s position could vary, the team learned that its size can vary as well. Reprogramming test equipment to recognize this shape, regardless of size or location, is the key to improving test sensitivity. "Our work can easily be incorporated into the protocol of any lab or testing instrument, so it could have an immediate impact on the trajectory of the health crisis,” commented Paul Patrone, NIST physicist.

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