High-sensitivity electrochemical immunosensor for anti-SARS-CoV-2 IgG detection using screen-printed carbon/cerium oxide-gold electrode: Original scientific aticle

Melania Janisha Devi; Ratu Shifa Syafira; Shabarni Gaffar; Irkham Irkham; Yasuaki Einaga; Yeni Wahyuni Hartati

doi:10.5599/admet.3182

Authors

Melania Janisha Devi Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang Km 21, Jatinangor, Sumedang, West Java 45363, Indonesia https://orcid.org/0000-0002-7165-033X
Ratu Shifa Syafira Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang Km 21, Jatinangor, Sumedang, West Java 45363, Indonesia https://orcid.org/0000-0002-6291-2465
Shabarni Gaffar Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang Km 21, Jatinangor, Sumedang, West Java 45363, Indonesia https://orcid.org/0000-0002-3659-4774
Irkham Irkham Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang Km 21, Jatinangor, Sumedang, West Java 45363, Indonesia https://orcid.org/0000-0001-9938-2931
Yasuaki Einaga Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama, 223-8522, Japan https://orcid.org/0000-0001-7057-4358
Yeni Wahyuni Hartati Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang Km 21, Jatinangor, Sumedang, West Java 45363, Indonesia https://orcid.org/0000-0003-1463-6352

DOI:

https://doi.org/10.5599/admet.3182

Keywords:

Electrochemical immunoassay, ceria-gold nanohybrid, modified carbon electrode, SARS-CoV-2 IgG antibodies

Abstract

Background and purpose: Serological assays are essential for evaluating immune responses, including donor screening, vaccine efficacy, and antibody persistence. However, conventional methods are time-consuming and require centralized laboratories. This study aimed to develop a sensitive and rapid electrochemical immunosensor based on a cerium
oxide-gold nanocomposite (CeO₂-Au) modified screen-printed carbon electrode (SPCE) for the detection of
anti-SARS-CoV-2 IgG, while elucidating the underlying electrochemical sensing mechanism. Experimental approach: CeO₂-Au nanocomposites were synthesized and characterized using UV-Vis, SEM, TEM-EDX, and FTIR. The immunosensor was fabricated by immobilizing SARS-CoV-2 Spike receptor-binding domain (RBD) onto the modified SPCE. Electrochemical responses were evaluated using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) with K₃[Fe(CN)₆] as a redox probe. Key results: The CeO₂-Au nanocomposite enhanced electron transfer and provided a high surface area for biomolecule immobilization. The sensing mechanism is governed by modulation of interfacial electron transfer: binding of IgG to immobilized RBD forms an insulating immunocomplex layer, increasing charge transfer resistance and suppressing faradaic current. The sensor exhibited a wide linear range of 0.01 to 10³ ng mL^-1, a low detection limit of 2.475 pg mL^-1, good stability, and reliable 97.3 to 108.56 % recovery in serum samples. Conclusion: This immunosensor proposed as a sensitive and reliable platform for IgG detection. The study advances understanding of signal transduction mechanisms in nanocomposite-based immunosensors and highlights their potential for rapid serological diagnostics. However, broader clinical validation and selectivity against complex interferents remain necessary.

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