In search of a new diagnostic method, the team chose a material often used in metallurgy – zinc oxide – and combined it for the first time with fluorine-doped tin oxide (FTO) glass, a conductive material used in photovoltaic and other electrodes. advanced applications.
“With this unusual combination and the addition of a biomolecule, the spike protein of the virus, we developed a surface capable of detecting antibodies against SARS-CoV-2. The result can be seen as an electrochemical signal captured by this surface,” said the chemist. Wendel Alves, lead author of the paper. Alves is a professor at the Center for Natural and Human Sciences, Federal University of ABC (UFABC), State of Sao Paulo.
The electrode developed by the researchers detected COVID-19 antibodies in serum in about five minutes with 88.7% sensitivity and 100% specificity, surpassing even the ELISA test, the current gold standard clinical diagnostic tool.
The research was supported by FAPESP National Science and Technology Institute for Bioanalysis and through a thematic project.
According to Alves, who heads UFABC’s Laboratory of Electrochemistry and Nanostructured Materials, prior knowledge of chemical properties such as the isoelectric point of the viral spike protein (S) allowed the team to develop a platform for S to electrostatically bind to zinc oxide nanorods. Zinc oxide is increasingly being used for the production of biosensors due to its versatility and unique chemical, optical and electrical properties.
The immunosensor is easy to manufacture and use, and its production costs are relatively low. “The group succeeded in developing the device thanks to its strong knowledge of new materials and the synthesis of zinc oxide nanorods,” said Alves. The nanorods form a film on the conductive surface of FTO, creating a favorable molecular microenvironment for protein S immobilization and making the construct a simple way to detect these antibodies.
Researchers are now adapting the platform to make it portable and connectable to mobile devices for use in diagnosing COVID-19 and other infectious diseases.
Analysis and future use
A total of 107 blood serum samples were analyzed. They were divided into four groups: pre-pandemic (15), recovered from COVID-19 (47), vaccinated without a previous positive disease (25) and vaccinated after a positive result (20). The vaccine was two doses of CoronaVac given four weeks apart. CoronaVac is produced by the Chinese company SinoVac in collaboration with the Butantan Institute (Sao Paulo state).
The authors of the article – researchers affiliated with the UFABC and the Heart Institute (INCOR), led by the School of Medicine of the University of Sao Paulo (FM-USP) – point out that the device detects antibodies produced in response to both viral infections. and vaccinations, and provides excellent opportunities for monitoring seroconversion and seroprevalence. Detection of vaccination response is important so that public health authorities can evaluate the effectiveness of different vaccines and vaccination campaigns or programs, they stress.
The device has been validated for detecting CoronaVac-induced immunity, but the team plans to expand its use to test response to vaccines from Pfizer and AstraZeneca.
One of the advantages of the electrode they developed is its flexible architecture, which means it can be easily tailored for other diagnostic and biomedical applications using different biomolecules on zinc oxide nanorods and other target analytes.
“The technology is a versatile biosensing platform. According to our developer, it can be modified and tailored for serological detection of other public health diseases,” said Alves.
HT