Impedimetric biosensor based on ZnO for detection of antibodies against SARS-CoV-2 Spike protein in human blood serum samples

Impedimetric biosensor based on ZnO for detection of antibodies against SARS-CoV-2 Spike protein in human blood serum samples

• Autor
• Freddy Alejandro Nunez Esteves
• Co-autores
• Ana Cristina Honorato Castro , Vivian De Oliveira , Wendel Andrade Alves
• Resumo

• COVID-19 is a disease caused by the SARS-CoV-2 coronavirus. Diagnostic methods based on electrochemical biosensors are promising alternatives to conventional laboratory tests. Zinc oxide (ZnO) is a semiconductor material with an isoelectric point (IEP) ~9.5. In this work, we developed a label-free impedimetric biosensor based on zinc oxide nanorods (ZnONRs), supported by the FTO. In which the recombinant Spike protein SARS-CoV-2 (S) was immobilized by physical adsorption (Granted by LECC/COPPE/UFRJ). Finally, the system was validated using clinical samples (1:500 v/v dilution) from healthy (pre-pandemic), convalescent and vaccinated (Sinovac-Coronavac) patients (CAAE:43139921.2.0000.5594). The presence of the ZnONRs matrix provides some resistive path for electron flow. However, it provides a suitable biocompatible environment for the immobilization of biomolecules. All modification steps were followed by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray photoelectron Spectroscopy (XPS) and electrochemical techniques. The morphology presented by the positive and negative samples were different. The strategy used allowed the retention of S, which was observed by the increase in charge transfer resistance (Rct) due to barriers created by the presence of the protein that delays electron transfer. As these are complex samples, glycine was used to avoid unspecific reactions with the medium, helping the system to easily distinguish positive and negative samples. In the test with clinical samples we studied 4 groups of patients (1) pre-pandemic; (2) Convalescents; (3) vaccinated and (4) vaccinated and diagnosed with COVID-19. From (1) we define the cut-off point (5.2 K?) and separate the 3 groups with good statistics. In group (3) we have some points, which represent patients with negative responses in the ELISA and positive responses in the electrochemical system. The ROC curve for the electrochemical system showed AUC ~ 0.91 which suggests that the proposed system is sensitive. Thus, the surface of ZnONRs was able to keep S in its trimeric form, allowing the differentiation of blood serum from healthy, infected with COVID-19 and vaccinated patients, proving to be a versatile platform for the development of electrochemical biosensors for monitoring the COVID-19.

   

• Palavras-chave
• COVID-19, SARS-CoV-2, Electrochemical biosensor, Zinc oxide, CoronaVac, Immunosurveillance
• Modalidade
• Comunicação oral
• Área Temática
• Nanociências & Nanotecnologia