Illustration of the structure of spike protein-modified zinc oxide and its interaction with antibodies in the sample. The novel method detects COVID-19 antibodies in five minutes. Photo credit: Karin Regina Leite de Oliveira/DK-Design
Fast, 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 have contributed to efforts in this area by developing an electrochemical immune sensor that detects antibodies to the virus. The innovation is described in a recent article published in the journal ACS Biomaterials Science and Engineering.
In search of a novel diagnostic method, the group chose a material commonly used in metallurgy – zinc oxide – and combined it for the first time with fluorine-doped tin oxide glass (FTO), a conductive material used, among other things, in electrodes for photovoltaic advanced applications.
“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 result is displayed as an electrochemical signal captured by this surface,” says chemist Wendel Alves , lead author of the article. Alves is a professor at the Center for Natural and Human Sciences, Federal University of the ABC (UFABC), State of São Paulo.
The electrode made by the researchers detected COVID-19 antibodies in serum in about five minutes with a sensitivity of 88.7% and a specificity of 100%, even surpassing the enzyme-linked immunosorbent assay (ELISA) test current gold standard tool for clinical diagnosis.
According to Alves, head of the UFABC Laboratory of Electrochemistry and Nanostructured Materials, prior knowledge of chemical properties such as the isoelectric point of virus spike protein (S) enabled the group to develop a platform for S to electrostatically attach to zinc oxide nanorods tie. Zinc oxide is increasingly being used to fabricate biosensors due to its versatility and unique chemical, optical, and electrical properties.
The immune sensor is easy to manufacture and use, and its production cost is relatively low. “The group was able to develop the device thanks to their extensive knowledge of novel 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 S-protein immobilization and making the construct an easy way to detect these antibodies.
Researchers will now adapt the platform to be wearable and connectable to mobile devices to be used to diagnose 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), COVID-19 convalescents (47), vaccinated without prior positive results for the disease (25), and vaccinated after a positive result (20). The vaccine consisted of two doses of CoronaVac given four weeks apart. CoronaVac is manufactured by the Chinese company SinoVac in collaboration with the Butantan Institute (State of São Paulo).
The authors of the article – researchers from UFABC and the Heart Institute (INCOR), operated by the University of São Paulo School of Medicine (FM-USP) – note that the device detects antibodies produced in response to both infections caused by the Virus are produced and vaccination and shows excellent potential as a tool to monitor seroconversion and seroprevalence. Recognizing the response to vaccination is important to help public health officials assess the effectiveness of different vaccines and immunization campaigns or programs, they stress.
The device has been validated for detecting CoronaVac-induced immunity, but the group plans to extend its use to testing for response to the Pfizer and AstraZeneca vaccines.
One of the advantages of the electrode they developed is its flexible architecture, which means it can be easily adapted for other diagnostic and biomedical applications by using different biomolecules on the zinc oxide nanorods and other target analytes.
“The technology is a versatile biosensor platform. As developed by us, it can be modified and adapted for serological detection of other diseases of public interest,” said Alves.
More information:
Freddy A. Nunez et al, Zinc oxide nanorod-based electrochemical immune sensors for the detection of antibodies against the SARS-CoV-2 spike protein in convalescent and vaccinated individuals, ACS Biomaterials Science & Engineering (2022). DOI: 10.1021/acsbiomaterials.2c00509
Citation: Novel Device Detects COVID-19 Antibodies in Five Minutes (2022, November 29) Retrieved November 29, 2022 from
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