Fast and sensitive determination of trace penicillin G at nanomolar quantity in environmental and food chains using enzyme-catalysed electrochemical sensing composite

Penicillin G (Pen G) residues enter the environment through pharmaceutical wastewater, agricultural runoff, medical waste, and animal manure, threatening ecosystems and human health. Therefore, developing a swift, efficient, and precise method for Pen G detection is crucial. Bismuth manganate (BiMn 2 O 5 ) was successfully synthesized using the chemical co-precipitation method. The synthesized BiMn 2 O 5 was then ultrasonically compounded with carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) in a chitosan (CS) solution. Subsequently, penicillinase (Pen X) was immobilized onto the CS/BiMn 2 O 5 /MWCNTs-COOH/GCE to augment the electrode’s catalytic function via enzymatic action, resulting in the Pen X/CS/BiMn 2 O 5 /MWCNTs-COOH/GCE composite electrode. Following optimization of the experimental conditions, quantitative detection of Pen G was conducted employing differential pulse voltammetry. The study revealed that the peak currents were wide linearly related to Pen G concentrations (0.0007–0.01, 0.03–1 µM), respectively. The detection limit was established at 0.14 nM, and the sensor demonstrated a high sensitivity with a value of 484.8 µA µM −1 . The recoveries from spiked milk and lake water samples were in the ranges of 94.4–106.3 % and 101.5–104.8 %, respectively. This work is crucial for protecting ecological balance, as it can monitor the misuse of Pen G, safeguard the health of aquatic ecosystems, and maintain human health.