Analytical Sciences

Sensitive Impedimetric Immunoassay of Japanese Encephalitis Virus Based on Enzyme Biocatalyzed Precipitation on a Gold Nanoparticle-modified Screen-printed Carbon Electrode

Xiaohui GENG,* Fanglin ZHANG,** Qiang GAO,* and Yingfeng LEI**

*Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an, 710062, China
**Department of Microbiology, Faculty of Preclinical Medicine, The Fourth Military Medical University, Xi’an, Shaanxi 710032, China

A sensitive and disposable electrochemical impedance biosensor to detect Japanese encephalitis virus (JEV) was developed based on a gold nanoparticle (AuNP)-modified screen-printed carbon electrode (SPCE). A biosensor was fabricated through covalent grafting of a mixed self-assembled monolayer on AuNPs with a specific antibody. To detect JEV and achieve signal amplification, the horseradish peroxidase (HRP)-labeled second antibody was linked to the biosensor through a sandwich immunity reaction. HRP was used to catalyze 4-chloro-1-naphthol oxidation to produce an insoluble precipitate, which introduced a barrier to electron transfer on the electrode. Electrochemical impedance spectroscopy (EIS) was used to monitor the precipitation on the electrode. The electron-transfer resistance (R_et) of the biosensor was directly correlated with the concentration of JEV in the solution. Under optimal conditions, the method generated a linear response range between 500 and 5 × 10⁵ pfu mL⁻¹, and the detection limit was 167 pfu mL⁻¹. The biosensor exhibited good selectivity against other viruses.

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