Antibody Conjugated with Gold Nanoparticle for COVID-19 Diagnosis in Saliva Samples

Antibody Conjugated with Gold Nanoparticle for COVID-19 Diagnosis in Saliva Samples

• Autor
• Fabiola Lelis de Castro
• Co-autores
• Ana Cristina Honorato Castro-Kochi , Vivian Leite de Oliveira , Silvia Beatriz Boscardin , Lídia M. Andrade , Wendel Andrade Alves
• Resumo

• Viruses are infectious agents responsible for numerous diseases, including the coronavirus pandemic, which has caused countless deaths in recent years. Combatting the spread of pandemics like COVID-19 requires the development of rapid, sensitive, and accessible diagnostic methods. This study focuses on developing a biosensor using anti-RBD antibodies conjugated with gold nanoparticles. Antibodies are employed as biorecognition molecules due to their selective molecular recognition capability. Conjugating these antibodies with gold nanoparticles aims to enhance performance by leveraging the characteristics of the nanoparticles, which contribute to better orientation and increased protein contact surface, thereby increasing the biosensor's sensitivity. This study presents the development of an electrochemical biosensor for COVID-19 diagnosis, utilizing gold nanoparticles conjugated with antibodies targeting the RBD domain of the SARS-CoV-2 Spike protein. FTO electrodes were modified with zinc oxide nanorods to create an impedimetric biosensor.[1] ELISA was used to evaluate the antibody's performance in detecting the RBD recombinant protein from five Variants of Concern (VoC) of SARS-CoV-2. Fluorescence spectroscopy characterized the conjugation of the antibody with the gold nanoparticle through the quenching effect on the material's fluorescence signal post-conjugation. Additionally, AFM analysis revealed distinct behaviors between the pure antibody and the antibody conjugated with the AuNPs, corroborating the fluorescence spectroscopy tests, which confirm an organizational change in the system after conjugation. The immobilized AuNPs-anti-RBD were characterized by cyclic voltammetry and impedance spectroscopy, indicated by a decrease in the oxidation peak potential of the redox couple and an increase in the semicircle diameter in the Nyquist diagrams. The biosensor demonstrated excellent response in detecting the target antigen, with a calibration curve showing a limit of detection (LOD) of 1.7 ?g mL-1. Electrochemical tests also displayed similar effectiveness in detecting the Omicron variant, consistent with the ELISA results. To develop a non-invasive and rapid diagnostic method, saliva samples were chosen for accurate testing. The results were promising, indicating the antibody's potential in recognizing the viral proteins of interest and demonstrating robust biosensor detection-response performance.

  [1] F.A. Nunez, A.C.H. Castro, V.L. de Oliveira, A.C. Lima, J.R. Oliveira, G.X. de Medeiros, G.L. Sasahara, K.S. Santos, A.J.C. Lanfredi, W.A. Alves. ACS Biomater. Sci. Eng. 2023, 9, 458.

• Palavras-chave
• Biosensors, SARS-Cov-2, Anti-RBD-antibodies,  Zinc Oxide
• Modalidade
• Pôster
• Área Temática
• Materiais Funcionais Avançados