One-step construction of MWCNTs@MoS2@Chitosan film for ciprofloxacin sensing and its oxidation mechanism

Abstract

Ciprofloxacin (CIP), extensively used in medical, agricultural, and forestry sectors as an antibiotic, poses risks of water contamination due to misuse or improper disposal, highlighting the pressing necessity for accelerated detection methods. Hydrophilic multi-walled carbon nanotubes (MWCNTs) and molybdenum disulfide (MoS2) were co-dispersed in a chitosan (CS) solution, which facilitates film formation. The high specific surface area of MWCNTs, coupled with the excellent semiconducting properties of MoS2 and the overall hydrophilicity of the composite nanomaterial film, markedly increases the active sites and reaction contact area. Subsequently, a drop-coating method was used to fabricate a MWCNTs@MoS2@Chitosan film onto the surface of a glassy carbon electrode (GCE) for CIP detection spanning from 0.50 to 1200.00 µmol/L using Differential Pulse Voltammetry (DPV), achieving a limit of detection (LOD) of 0.16 µmol/L. Simultaneously, the sensor demonstrates excellent reproducibility, stability, and selectivity. In several real water samples, the sensor performance was verified using a spiked recovery method. And in three water samples the recoveries ranged from 98.38 to 113.53 %, with a relative standard deviation (RSD) of less than 4.80 %. Meanwhile, the accuracy of these result was verified using UV–visible (UV–vis) spectroscopy. Furthermore, we proposed an electrooxidation mechanism for CIP that involves a reaction with two electrons and two protons.