Rapid, cheap and accurate tests remain essential for epidemiological surveillance and for health services to control and contain the spread of SARS-CoV-2. Brazilian scientists have contributed to efforts in this field by developing an electrochemical immunosensor that detects antibodies against the virus. The innovation is described in a paper recently published in the journal ACS Biomaterials Science and Engineering.
In search of a new diagnostic method, the group chose a material frequently used in metallurgy, zinc oxide, and combined it for the first time with tin oxide glass doped with fluorine (FTO), a conductive material used in electrodes for photovoltaics and other advanced applications.
“With this unusual combination and the addition of a biomolecule, the viral spike protein, we have developed a surface capable of detecting antibodies against SARS-CoV-2. The result is shown as an electrochemical signal captured by this surface” , said chemist Wendel Alves. , lead author of the article. Alves is a professor at the Center for Natural and Human Sciences of the Federal University of the ABC (UFABC), in the state of São Paulo.
The electrode made by the researchers detected COVID-19 antibodies in serum in about five minutes with 88.7% sensitivity and 100% specificity, even surpassing the enzyme-linked immunosorbent assay (ELISA) test, the gold standard clinical diagnostic tool.
The research was supported by FAPESP through the National Institute of Science and Technology for Bioanalysis and a Thematic Project.
According to Alves, who directs the Laboratory of Electrochemistry and Nanostructured Materials at UFABC, prior knowledge of chemical properties such as the isoelectric point of the spike protein (S) of the virus allowed the group to develop a platform for S to attach electrostatically to zinc oxide nanooxides. Zinc oxide is increasingly used to fabricate biosensors due to its versatility and unique chemical, optical, and electrical properties.
The immunosensor is easy to make and use, and its production cost is relatively low. “The group managed to develop the device thanks to their great knowledge of new materials and the synthesis of zinc oxide nanorods,” said Alves. The nanorods form a film on the conductive surface of the FTO, creating a favorable molecular microenvironment for protein S immobilization and making the construct a simple way to detect these antibodies.
The researchers will now adapt the platform to make it portable and connectable to mobile devices for use in the diagnosis of COVID-19 and other infectious diseases.
Analysis and future uses
A total of 107 blood serum samples were analyzed. They were divided into four groups: prepandemic (15), convalescent from COVID-19 (47), vaccinated without previous positive results for the disease (25), and vaccinated after a positive result (20). The vaccine was two doses of CoronaVac administered four weeks apart. CoronaVac is produced by the Chinese company SinoVac in collaboration with Butantan Institute (state of São Paulo).
The authors of the article, researchers affiliated with the UFABC and the Heart Institute (INCOR), directed by the Faculty of Medicine of the University of São Paulo (FM-USP), point out that the device detects antibodies produced in response to both virus infections. and vaccination, and shows excellent potential as a tool for monitoring seroconversion and seroprevalence. Detecting the response to vaccination is important to help public health authorities evaluate the effectiveness of different vaccines and immunization campaigns or programs, they emphasize.
The device has been validated to detect immunity induced by CoronaVac, but the group plans to expand its use to Pfizer and AstraZeneca vaccine response tests.
One of the advantages of the electrode they developed is its flexible architecture, which means it can be easily customized for other diagnostic and biomedical applications by using different biomolecules on the zinc oxide nanorods and other target analytes.
“The technology is a versatile biodetection platform. As we have developed, it can be modified and customized for serological detection of other diseases of public health interest,” said Alves.
Source:
São Paulo Research Foundation (FAPESP)
Journal reference:
10.1021/acsbiomaterials.2c00509