Electrochemically ultrasensitive detection of ampicillin using enzyme-mediated metallo-β-lactamase/CS/Bi2WO6/MWCNTs-COOH biosensor

Scheme of preparation of MBLs/CS/Bi2WO6/MWCNTs-COOH/GCE for AMP detection. This illustrated summary describes how flower-like Bi2WO6 was prepared by a hydrothermal method and Bi2WO6/MWCNTs-COOH composite nanomaterials were prepared by ultrasonic mixing. The sensor utilized chitosan (CS) to immobilize MBL on the surface of the Bi2WO6/MWCNTs-COOH-modified electrode, which achieved efficient, rapid and reproducible detection of AMP content. Meanwhile, the excellent stability, high surface area and easy adsorption of bimetallic salt nanomaterial detection materials, combined with the sensor, will surely play a great advantage in the future drug detection field. [Display omitted] •An enzymatic AMP sensor based on MBLs/CS/Bi2WO6/MWCNTs-COOH/GCE was presented.•The composite electrode greatly improved sensitivity and specificity performances.•AMP sensing covers a wide linear range (0.0007–0.05 µM; 0.1–10 µM) with a LOD of 0.17 nM.•The biosensor performed well in real scenarios including milk and lake water samples. The misuse of the antibiotic ampicillin (AMP) has led to the presence of antibiotic residues in related products, which enter the human body through the ecological or food chain to produce a variety of toxic side effects. There is an urgent need to develop enzyme-based assays with higher specificity to determine antibiotic residues in food. Hereby, bismuth tungstate (Bi2WO6) was synthesized using a simple hydrothermal and calcination process. Carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) were mixed with Bi2WO6 by ultrasonication to form composite as modifier on glassy carbon electrode (GCE) surface. Meanwhile, metal β-lactamases (MBLs) were mixed with chitosan to be immobilized on it to obtain the MBLs/CS/Bi2WO6/MWCNTs-COOH/GCE. Under the optimal conditions, differential pulse voltammetry (DPV) was used for the quantitative detection of AMP. The experimental results showed that the peak currents were linearly correlated with the concentrations of AMP (0.0007–0.05 μM) and (0.1–10 µM) (R2 = 0.9965 and 0.9956), and the detection limit was 0.17 nM (S/N = 3). The method has good repeatability, reproducibility, stability and immunity to interference, and can be applied to the highly sensitive detection of AMP in real samples with recoveries of 92.4–96.8 % and 94.3–103.0 %.