Rapid, inexpensive and accurate testing remains essential for epidemiological surveillance and for health services to monitor and contain the spread of SARS-CoV-2. Brazilian scientists are contributing to efforts in this area by developing an electrochemical immunosensor that detects antibodies to viruses.
Seeking a new diagnostic method, the group chose zinc oxide, a material frequently used in metallurgy, to replace it with fluorine-doped tin oxide (FTO), a conductive material used in electrodes such as in photovoltaics. For the first time, it was combined with glass. Advanced application.
“With this unusual combination and the addition of a biomolecule, the viral spike protein, we have developed a surface that can detect antibodies against SARS-CoV-2. The results are displayed as an electrochemical signal captured by this surface.” , says chemist Wendel Alves, lead author of this article. Alves is a professor at the Center for Natural and Human Sciences at the ABC Federal University of Sao Paulo (UFABC).
The researchers’ fabricated electrodes detected COVID-19 antibodies in serum in about 5 minutes with 88.7% sensitivity and 100% specificity, surpassing the current gold standard clinical diagnostic tool, enzyme-linked immunosorbent assay (ELISA). ) better than test.
This work was supported by FAPESP via the National Institute of Science and Technology Bioanalytical and Thematic Projects.
According to Alves, who heads the Laboratory for Electrochemistry and Nanostructured Materials at UFABC, prior knowledge of the chemical properties of the viral spike protein (S), such as the isoelectric point, allowed the group to attach S to the zinc oxide nanorods electrostatically. We were able to develop a platform to combine. Zinc oxide is increasingly used in biosensor fabrication due to its versatility and unique chemical, optical, and electrical properties.
Immunosensors are easy to make and use, and their manufacturing costs are relatively low. “The group successfully developed the device thanks to their strong knowledge of novel materials and zinc oxide nanorod synthesis,” said Alves. The nanorods form a membrane on the conductive surface of FTO, creating a suitable molecular microenvironment for immobilization of S protein and constructing a simple method for detecting these antibodies.
Researchers are now making the platform portable and connectable to mobile devices for use in diagnosing COVID-19 and other infectious diseases.
Analysis and future use
A total of 107 serum samples were analyzed. They divided him into four groups: pre-pandemic (15), COVID-19 convalescent (47), vaccinated without previous positive disease test (25), and post-positive test. vaccinated (20). The vaccine is Coronavac, which he gave two doses four weeks apart. CoronaVac is manufactured by the Chinese company SinoVac in partnership with the Butantan Institute (São Paulo).
The authors of the article, UFABC and researchers at the Heart Institute (INCOR) run by the University of São Paulo School of Medicine (FM-USP), said the device detects antibodies produced in response to both infections by the virus. I am paying attention to that. and vaccination, and as a tool for monitoring seroconversion and seroprevalence. They emphasize that detecting responses to vaccination helps public health officials assess the effectiveness of different vaccines and immunization campaigns or programs.
The device has been validated to detect immunity induced by CoronaVac, but the group plans to extend its use to test responses to vaccines from Pfizer and AstraZeneca.
One of the advantages of the electrode they developed is its flexible architecture. This means that various biomolecules and other target analytes on zinc oxide nanorods can be used and easily customized for other diagnostic and biomedical applications.
“This technology is a versatile biosensing platform. As we developed it, it can be modified and customized for serological detection of other diseases of public health interest,” said Alves. says Mr.
reference: Nunez FA, Castro ACH, de Oliveira VL et al. Electrochemical immunosensors based on zinc oxide nanorods for the detection of antibodies to the SARS-CoV-2 spike protein in convalescent and vaccinated individuals. ACS Biometer Science Engineering 2022: acsbiomaterials.2c00509. Doi: 10.1021/acsbiomaterials.2c00509
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