Banca de DEFESA: FREDDY ALEJANDRO NUNEZ ESTEVES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : FREDDY ALEJANDRO NUNEZ ESTEVES
DATE: 24/07/2025
TIME: 14:00
LOCAL: Auditório 801 no 8º andar do Bloco B do Campus de Santo André da Universidade Federal do ABC e (meet.google.com/aqx-hdsg-eas)
TITLE:

Zinc Oxide Nanorod-Based Electrochemical Biosensors for Detecting SARS-CoV-2 Antibodies and Spike Protein

PAGES: 150
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Eletroquímica
SUMMARY:

The COVID-19 pandemic exposed critical limitations in global diagnostic infrastructure and emphasized the need for rapid, decentralized, and accurate serological tools. In this study, we developed and evaluated a series of electrochemical biosensors based on zinc oxide nanorods (ZnONRs) for the detection of anti-SARS-CoV-2 antibodies and Spike protein antigens in human serum. Four biosensing platforms were constructed: (i) a device using the recombinant trimeric Spike protein from the SARS-CoV-2 wild-type (WT); (ii) an immunosensor functionalized with the Spike protein from the Gamma variant (P.1); (iii) a peptide-based biosensor employing the immunodominant B-cell epitope P44 (from the receptor-binding domain); and (iv) a biosensor using an ACE-2 peptide immobilized on Ni-doped ZnONRs for antigen detection.
All devices were fully characterized and validated with serum samples from infected, convalescent, vaccinated (CoronaVac, ChAdOx1-S, and BNT162b2), and pre-pandemic individuals. The WT Spike-based immunosensor demonstrated 88.67% sensitivity and 100% specificity, with a limit of detection (LOD) of 19.34 ng·mL⁻¹. The Gamma variant sensor showed an LOD of 52.55 ng·mL⁻¹ and revealed stronger antibody responses in BNT162b2-vaccinated individuals compared to ChAdOx1-S. The P44 peptide-based device effectively recognized WT antibodies targeting single-residue mutations (K417) in WT, Gamma, and Omicron variants, with sub-nanogram LODs. Finally, the ACE-2-based sensor enabled direct Spike antigen detection, with an LOD of 60.13 ng·mL⁻¹ and AUC of 0.917.
The results highlight the versatility, sensitivity, and diagnostic potential of the ZnONRs-based biosensors for point-of-care applications in immunological surveillance and COVID-19 variant monitoring.

COMMITTEE MEMBERS:
Presidente - Interno ao Programa - 1544341 - WENDEL ANDRADE ALVES
Membro Titular - Examinador(a) Interno ao Programa - 2605463 - JOSE ANTONIO SOUZA
Membro Titular - Examinador(a) Externo ao Programa - 1676378 - ADRIANO REINALDO VICOTO BENVENHO
Membro Titular - Examinador(a) Externo ao Programa - 1814655 - LUCIA HELENA GOMES COELHO
Membro Titular - Examinador(a) Externo à Instituição - JOSÉ ALBERTO FRACASSI DA SILVA - UNICAMP
Membro Suplente - Examinador(a) Interno ao Programa - 007.041.553-62 - RENATO SOUSA LIMA - UNICAMP
Membro Suplente - Examinador(a) Externo ao Programa - 1909336 - ALEXANDRE ZATKOVSKIS CARVALHO
Membro Suplente - Examinador(a) Externo à Instituição - WILLIAM REIS DE ARAUJO - UNICAMP
Membro Suplente - Examinador(a) Externo à Instituição - FLAVIO SANTOS DAMOS - UFMA