Due to the complex characteristics of food matrix, false positives may occur when using traditional methods to detect aflatoxin B1 (AFB1). In this paper, we utilize the advantages of closed bipolar electrode (BPE) that can effectively avoid the impact of complex food matrices on signal collection, and design a biosensor based on immune competition to detect highly toxic AFB1. The biosensor uses cathode of closed BPE as a functional sensing interface and anode as a signal collection interface. On the functional sensing interface, AFB1 connects to the monoclonal antibody at the top of DNA tetrahedron structure. Under the action of horseradish peroxidase (HRP), 4-chloro-1-naphthol (4-CN) is catalyzed by hydrogen peroxide (H 2 O 2 ) to generate precipitations (4-CD). AFB1 competes with HRP-AFB1 to bind monoclonal antibody, resulting in a decrease in the content of HRP involved in catalytic oxidation reactions and a synchronous reduction in precipitations produced, causing an increase in the intensity of [Ru(bpy) 3 ] 2+ /TPA system electrochemiluminescence (ECL) on the BPE anode. Analysis shows that the relative deviation between the detection results and ELISA is between −4.5 and 9.8%, and there is no significant difference in the performance of the two in detecting AFB1. The BPE-ECL sensor exhibits high sensitivity and specificity in detecting AFB1, with a linear range of 0.01–40 ng mL −1 and a detection limit of 3 pg mL −1 . In the future, it can be applied to the detection of other toxins, with broad application prospects.
A microfluidic gradient array is a widely used screening and analysis device, which has characteristics of high efficiency, high automation, and low consumption. Bipolar electrode electrochemiluminescence (BPE-ECL) has special value in microfluidic array chips. The combination of the microfluidic gradient and BPE arrays has potential for high-throughput screening. In this article, a microfluidic BPE array chip for gradient culture and conditional screening of cancer cells was designed. The generation of concentration gradients, continuous culture of cancer cells with high throughput, and drug screening through BPE-ECL of the Ru(bpy)32+/TPrA system can be performed in one chip. We tested gradient pro-oxidation of MCF-7 by ascorbic acid and the synergistic effect of pro-oxidation on doxorubicin. The method achieves high analysis efficiency through a BPE array while simplifying the tedious procedures required by cell culture methods.
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