Preparation of electrochemical sensor based on glassy carbon electrode and its specificity and sensitivity for directional detection of antibiotic resistance genes spreading in the water environment.

Antibiotic-resistant bacteria/resistance genes (ARB/ARGs) have been paid much attention due to the environmental risks they might bring. They were demonstrated to be widespread in surface water and wastewater. Determining the concentrations of ARGs is the first step to evaluate the degree of pollution. In this study, electrochemical detection technology was studied due to its advantages of low cost, fast response, and satisfactory selectivity. Additionally, the electrochemical sensor technology was used to determine the concentration of a ubiquitous ARG (ampicillin gene blaTEM) in the water environment. A kind of electrochemical sensor was prepared on a glassy carbon electrode (GCE). The results of X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) curves indicated that the single-stranded DNA (ssDNA) probe can be successfully immobilized on the surface of the GCE. In addition, the performance of hybridization between the ssDNA probe and the target DNA at diverse temperatures was compared, of which 35 °C was the optimum. Moreover, the change of charge transfer resistance (ΔRct) for the GCE sensor hybridizing with complementary DNA was much higher than that of DNA with the mismatched base, which indicated that the electrochemical sensor prepared in this study was specific. The sensitivity of the sensor was also proved by the strong correlation between the concentrations of ARGs and ΔRct (with the correlation coefficient (R2) of 0.9905). All in all, this study is meaningful for the comprehend on the detection of ARGs through the electrochemical method.