Banca de QUALIFICAÇÃO: FREDDY ALEJANDRO NUNEZ ESTEVES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : FREDDY ALEJANDRO NUNEZ ESTEVES
DATE: 28/11/2022
TIME: 14:00
LOCAL: Remoto (meet.google.com/reo-tgsf-sny)
TITLE:

ELECTRONIC DEVICE BASED ON ZINC OXIDE NANORODS FOR DETECTION OF ANTI-SARS-CoV-2 ANTIBODIES

PAGES: 78
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Eletroquímica
SUMMARY:

Even after over two years of the COVID-19 pandemic, research in 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. It can be especially relevant for broadly used inactivated whole virus vaccines, such as CoronaVac, that showed lower efficacy for specific groups, such as the elderly and immunocompromised, and produced lower titers of neutralizing antibodies. In this work, we developed an impedimetric biosensor based on the immobilization of SARS-CoV-2 recombinant trimeric Spike Protein (S Protein) onto zinc oxide nanorods (ZnONRs) modified FTO substrate 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 (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), and electrochemical techniques. We successfully evaluated the applicability of the modified ZnONRs electrodes using serum samples from convalescent COVID-19 individuals, CoronaVac vaccinated with or without positive results for COVID-19 disease, and pre-pandemic samples from healthful 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 performed to test the specificity of immunosensor detection. No cross-reactivity with HCoVs was detected using the ZnONRs 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 (CoronaVac) and shows excellent potential as a tool for the population's assessment and monitoring of seroconversion and seroprevalence. We also evaluated the immunosensor response against serum from individuals vaccinated with ChAdOx1-S (Oxford-AstraZeneca) and BNT162b2 (Pfizer-BioNTech). Finally, the ZnO immunosensor was functionalized with the recombinant trimeric Spike Protein from the SARS-CoV-2 variant of concern P.1 (Gamma) and used to respond against negative control samples and vaccinated individuals (Oxford-AstraZeneca and Pfizer-BioNTech) with excellent performance. The immunosensor comparison data of vaccine-induced humoral immunity reveals that the Pfizer-BioNTech vaccine triggers significantly more antibodies anti-spike protein variant P.1 than the Oxford-AstraZeneca vaccine, reinforcing the great potential of this point-of-care technology.

BANKING MEMBERS:
Presidente - Interno ao Programa - 1545738 - MARCIA TSUYAMA ESCOTE
Membro Titular - Examinador(a) Interno ao Programa - 1763495 - WANIUS JOSE GARCIA DA SILVA
Membro Titular - Examinador(a) Externo ao Programa - 1909336 - ALEXANDRE ZATKOVSKIS CARVALHO
Membro Titular - Examinador(a) Externo ao Programa - 1544394 - PAULA HOMEM DE MELLO
Membro Suplente - Examinador(a) Interno ao Programa - 1768959 - FERNANDO CARLOS GIACOMELLI
Membro Suplente - Examinador(a) Interno ao Programa - 1545089 - DANIEL ZANETTI DE FLORIO
Membro Suplente - Examinador(a) Externo ao Programa - 1654772 - CAMILO ANDREA ANGELUCCI
Membro Suplente - Examinador(a) Externo ao Programa - 1544365 - GISELLE CERCHIARO