New device identifies antibodies against Covid-19 in five minutes

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Fast, cheap and accurate tests remain essential for health surveillance services to monitor and contain the spread of the Sars-CoV-2 virus and researchers have developed a sensor capable of helping in this objective. The work was considered relevant in the area and was featured on the cover of the ACS Biomaterials Science and Engineering magazine.

To develop this new diagnostic method, the group used a material commonly known in the field of metallurgy, zinc oxide, combined in an unprecedented way with FTO, an electron-conducting glass.

“Through this unusual combination and adding a biomolecule, the Spike viral protein, it was possible to develop a surface capable of detecting antibodies against the Sars-CoV-2 virus. The result is read by capturing an electrochemical signal on the developed surface “, explains chemist Wendel Alves, professor at the Center for Natural and Human Sciences at the Federal University of ABC (UFABC) and lead author of the article.

The electrode created detected antibodies against the new coronavirus in serum samples in about five minutes, with a sensitivity index of 88.7% and specificity of 100%. The results revealed a number of hits even higher than that of the conventional Elisa test (enzymatic immunosorbent assay), the gold standard currently used.

The work was supported by Fapesp through the National Institute of Science and Technology of Bioanalytics (INCTBio) and a Thematic Project. Alves, who conducts research at the Laboratory of Electrochemistry and Nanostructured Materials (LEMN) at UFABC, says that knowledge of chemical properties, such as the isoelectric point of the Spike protein of SARS-CoV-2, allowed the development of a platform in which it was retained by through electrostatic bonding with zinc oxide nanorods. This compound, by the way, has been increasingly used in the production of biosensors because of its versatility and differentiated chemical, optical and electrical properties.

Easy to produce and use, the immunosensor also has a relatively low manufacturing cost. “It was made possible thanks to the use of the research group’s strong knowledge of new materials and the ability to synthesize zinc oxide nanorods, the so-called ‘nanorods’, by modifying the surface of a conductive glass, the FTO”, details Alves. This process made it possible to create a favorable molecular microenvironment for the immobilization of the Spike viral protein on the electroconductive surface, transforming this construction into a simple device for detecting antibodies against Sars-CoV-2.

The group’s perspective is to adapt the platform to make it portable, allowing the connection of mobile devices to facilitate the detection of antibodies against Covid-19 and other infectious diseases.

Analysis and future uses

For the tests, 107 samples were analyzed, divided into four groups: pre-pandemic (15); convalescents from Covid-19 (47); vaccinated with no previous positive result for the disease (25); vaccinated with a previous positive result (20). Vaccinates had received two doses of Coronavac, four weeks apart.

One of the highlights highlighted by the researchers is that the antibodies detected in the developed platform can be either from infection by the coronavirus or from an immune response induced by a vaccine. This second application is very important to assist public health actions by monitoring the effectiveness of different vaccination programs and campaigns.

The work is signed by researchers from UFABC and the Instituto do Coração (InCor) of the Faculty of Medicine of the University of São Paulo (FM-USP), who point out the importance of monitoring seroconversion rates and seroprevalence of immunity generated after vaccination. The device is currently validated for detecting Coronavac-induced immunity, but the group plans to expand to also test the response of other manufacturers such as Pfizer and AstraZeneca.

One of the advantages of the developed electrode is its flexible architecture, having potential for other biomedical and diagnostic applications from adaptations and customizations. “The technology generated is a versatile biosensing platform. With the mastery of this technology, it is possible to modify and customize it for the serological detection of other diseases of interest to public health”, points out Alves.

The full text of the article “Electrochemical immunosensors based on zinc oxide nanorods for detection of antibodies against SARS-CoV-2 spike protein in convalescent and vaccinated individuals” (“Electrochemical immunosensors based on zinc oxide nanorods for detection of antibodies against Sars spike protein -CoV-2 in convalescent and vaccinated individuals”) can be accessed here.

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