Electrochemical Immunosensors Based on Zinc Oxide Nanorods for Detection of Antibodies Against SARS-CoV-2 Spike Protein in Convalescent and Vaccinated Individuals

Abstract

Even after over 2 years of the COVID-19 pandemic, research on rapid, inexpensive, and accurate tests remains essential for controlling and avoiding the global spread of SARS-CoV-2 across the planet during a potential reappearance in future global waves or regional outbreaks. Assessment of serological responses for COVID-19 can be beneficial for population-level surveillance purposes, supporting the development of novel vaccines and evaluating the efficacy of different immunization programs. This can be especially relevant for broadly used inactivated whole virus vaccines, such as CoronaVac, which produced lower titers of neutralizing antibodies. and showed lower efficacy for specific groups such as the elderly and immunocompromised. We developed an impedimetric biosensor based on the immobilization of SARS-CoV-2 recombinant trimeric spike protein (S protein) on zinc oxide nanorod (ZnONR)-modified fluorine-doped tin oxide substrates for COVID-19 serology testing. Due to electrostatic interactions, the negatively charged S protein was immobilized via physical adsorption. The electrochemical response of the immunosensor was measured at each modification step and characterized by scanning electron microscopy and electrochemical techniques. We successfully evaluated the applicability of the modified ZnONR electrodes using serum samples from COVID-19 convalescent individuals, CoronaVac-vaccinated with or without positive results for SARS-CoV-2 infection, and pre-pandemic samples from healthy volunteers as controls. ELISA for IgG anti-SARS-CoV-2 spike protein was performed for comparison, and ELISA for IgG anti-RBDs of seasonal coronavirus (HCoVs) was used to test the specificity of immunosensor detection. No cross-reactivity with HCoVs was detected using the ZnONR immunosensor, and more interestingly, the sensor presented higher sensitivity when compared to negative ELISA results. The results demonstrate that the ZnONRs/spike-modified electrode displayed sensitive results for convalescents and vaccinated samples and shows excellent potential as a tool for the population’s assessment and monitoring of seroconversion and seroprevalence.

ZnO-Based Electrochemical Immunosensor to Assess Vaccine-Induced Antibody-Mediated Immunity against Wild-Type and Gamma SARS-CoV-2 Strains

“…Our experimental data prove that this biosensor architecture is modular and adaptable to evaluate antibody-mediated immunity against another highly transmissible SARS-CoV-2 strain, the Gamma coronavirus variant, also called the P.1 strain, one of the most virulent strains, which appears to have evolved and devastated the city of Manaus, the capital of Amazon State in Brazil, causing a deadly second wave of infections in early 2021. It is worth noting that the assessment of vaccine-elicited immunity by the FTO-ZnONRs/spike WT immunosensor showed greater titres of anti-S antibodies in serum samples from vaccinated study participants of both vaccines analyzed, ChAdOx1-S (Oxford–AstraZeneca) and BNT162b2 (Pfizer–BioNTech), when compared to the previously published study from our group, based on serum samples from study participants vaccinated with the inactivated virus-based CoronaVac vaccine [ 16 ].…”

“…Previous work by our group [ 16 ] demonstrated the successful development and validation of a serological point-of-care ZnONRs/spike immunosensor to detect anti-SARS-CoV-2 antibodies in individuals immunized with an inactivated COVID-19 vaccine (SinoVac–CoronaVac). The electrochemical immunosensor was developed with the immobilization of the recombinant trimeric S protein by zinc oxide nanorods (ZnONRs) over the chemically modified fluorine-doped tin oxide (FTO) substrate.…”

Immunosensors for Assay of Toxic Biological Warfare Agents

“…Biosensor analytical devices have progressed from simple detectors containing crude enzymes, such as glucose oxidase, to complex systems where purposely prepared biological origin molecules, nanomaterials, and other advanced techniques are used [ 39 , 40 , 41 , 42 ]. Immunosensors are a variant of a biosensor where an antibody plays the role of a biorecognition element, and an antigen is an analyte [ 43 , 44 , 45 , 46 , 47 ]. Conception in which an immunosensor containing an antibody is detected by an antigen is possible as well [ 48 ].…”

Why Are There So Many Puzzles in Fighting against COVID-19 Pandemic?

“…In mammalian nerve and muscle cells, such a membrane potential can reach a level of approximately −100 mV, and could be much higher in some marine organisms such as squid because the concentrations of intracellular potassium ions in their excitable cells can reach approximately 400 mM, which is more than twice that of mammalian excitable cells (approximately 140 mM) [11]. The intracellular negative membrane potential established due to the concentration difference of potassium ions inside and outside can prevent microorganisms, such as viruses and bacteria, from contacting cells, that is to say, the body cells can resist the invasion of viruses into cells through the mechanism of biophysical action (bioelectricity) because viruses are usually negatively charged [19][20][21], which is an important natural immune mechanism;…”

“…The novel coronavirus (SARS-CoV-2) and its variety that causes coronavirus disease 2019 (COVID- 19) Open Access Natural Science have had a great impact on human health and society since it was epidemic in 2019. To date, its pandemic has been repeated and has not ended yet.…”