Nanosilver-mediated enzyme-free electrochemical immunosensor with enhanced stability for aflatoxin B1 detection in food safety†

Abstract

The development and research of electrochemical immunoassays have attracted considerable attention. However, traditional electrochemical immunoassays inevitably require the participation of biological enzymes, which suffer from high cost, poor stability, inconvenient storage and easy inactivation. Herein, we constructed a bio-enzyme-free electrochemical immunoassay system specifically for the detection of aflatoxin B1 (AFB₁). This method was based on the traditional antigen–antibody immune recognition system utilizing the nanosilver particles (NSPs) as signal markers to replace conventional natural enzymes. Subsequently, the labeled NSPs were transferred to silver ions in the presence of nitric acid. The concentration of silver ions was determined using anodic stripping voltammetry (ASV), which correlates closely to the concentration of the target. The current intensity measured by the bio-enzyme-free electrochemical sensor exhibited a negative correlation with the concentration of AFB₁. Under optimized conditions, the electrochemical sensor was used to detect AFB₁ in the dynamic concentration range of 0.01–100 ng mL⁻¹, and the limit of detection was 0.4882 pg mL⁻¹. The spiked recovery range of AFB₁ in corn starch was determined to be between 100.98% and 109.42%, while the relative standard deviation (RSD) range was found to be from 0.34% to 3.82%. These results indicate that the electrochemical immunosensor without biological enzyme labeling has reliable accuracy, and the sensor has a broad application prospect in AFB₁ detection.