Medicines

The handheld microfluidic device is a cost-free and portable device that provides an easy readout of the SARS-CoV-2 detection

Since the end of 2019, the coronavirus (COVID-19) epidemic has caused havoc on public health and the world economy, with approximately 265 million confirmed cases and the death toll being more than 5.25 million to the date.

COVID-19 may be caused by infection with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) the virus that can cause lung disease and even death. Therefore, early identification of infected persons is critical in preventing the spread of COVID-19.

Currently SARS-CoV-2 testing is conducted using a variety of molecular concepts each with limitations. The reverse transcription-polymerase chain reaction/quantitative polymerase chain reaction (RT-PCR/qPCR) detects viral nucleic acids in nucleic acid (NA) testing, often known as molecular testing. It is widely considered the gold standard for SARS-CoV-2 testing and is routinely used to diagnose COVID-19. However, NA tests can be time-consuming and labor-intensive and may not be readily available in places where resources are limited or are not readily accessible.

Study Handheld Microfluidic Filtration Platform Enables Rapid, Low-Cost, and dependable self-testing of SARS-CoV-2 Virus. Image Credit: Creativeneko / Shutterstock

Serological antibody tests however test for antibodies produced by the immune response to viral infections. These tests are limited by the kinetics of antibody production within the body. It can take up to a week for a concentration that is measurable to be reached.

Due to their high sensitivity, microfluidic immunoassays made with pregrafted Aptamers are often used to identify biomarkers. However, its capacity to perform exact analysis relies on the assumption of the lateral flow being low-throughput and a difficult flow rate or pressure control. The conventional microfluidic-based immunoassay could not meet the demands of fast COVID-19 antibody detection.

This method requires skilled handling and sophisticated devices like flow pumps or biochemical signal readers. These devices are often not available in areas with poor or resource-scarce regions.

Extreme instrument dependence can also make it more difficult and costly of conducting parallel testing. As a result, it’s critical to create a rapid, high-throughput, accurate, and instrument-independent technology for detecting SARS-CoV-2.

This study is available in the journal Small.

The study

In this paper, a group of researchers from Harvard Medical School, McGill University, and Tianjin University describes an on-chip diagnostic technique to detect the direct presence of SARS-CoV-2 N protein in nasal samples that combines the advantages of microfluidic filtration using hydrodynamics and sandwich immunoassay.

In the context of a sandwich ELISA method, 22 monoclonal antibodies from commercial sources against either SARS-CoV-2 spike (S) or nucleocapsid (N) protein were evaluated for specificity and sensitivity.

The test was microfluidic and showed an sensitiveness of 95.4 percent and 100% specificity beating all known tests that use eye-visible readouts for nasal specimen detection, as well as a variety of instrument-dependent readout assays.

This was due to the fact that the chip could handle significantly more sample (1 mL) and utilized a rapid hydrodynamic filtration to collect and enrich trace levels of antigens instead of gradual spontaneous accumulation on a surface with lateral flow.

As a result of these variations, the color contrast was enhanced and measurement errors were minimized. Because the assay’s sensitivity is cycle threshold- (Ct-)dependent, further data analysis revealed a strong relationship between the assay and the qPCR approach. The assay showed an extremely high sensitivity of 100 percent for samples with Ct 20 and a lower sensitivity of 87.5% for samples with higher Ct values. This is consistent with the discovery by the authors that viral particle dosage is dependent on dose.

There were 21 self-reported symptomatic and 61 asymptomatic participants within the study. Some symptomatic participants were not infected according to qPCR results.

The on-chip test was consistent with qPCR and there were no false positives in this group of PCR-negative, symptomatic individuals. A clinical testing method’s ability to detect the presence of asymptomatic infections is an important indicator.

The test performed on the chip showed 95.7 percent sensitivity and % specificity in 61 asymptomatic people, indicating that sensitivity and specificity are comparable in both asymptomatic and symptomatic people. Taken as a whole the test performed by microfluidics showed adequate sensitivity and high specificity.

Implications

The authors present a straightforward, cost-effective, and rapid microfluidic-based testing platform for detecting SARS-CoV-2 antigens in this study. In clinical trials, the microfluidic test kit performed better than the standard SARS-CoV-2 virus as well as variants. The microfluidic platform can allow for further technological advances. This microfluidic test kit that is extremely sensitive and is commercially available, is ideal for SARS-2 testing in rural areas without lab equipment.

Journal reference:

Content Source: https://www.news-medical.net/news/20211205/Equipment-free-handheld-microfluidic-injection-provides-visible-readout-of-SARS-CoV-2-detection.aspx

Gemma Wilson

Gemma is a journalism graduate with keen interest in covering business news – specifically startups. She has as a keen eye for technologies and has predicted quite a few successful startups over the last couple of years.

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