Gold Nanoparticle-Embedded Thiol-Functionalized Ti₃C₂T_x MXene for Sensitive Electrochemical Sensing of Ciprofloxacin

The unregulated use of ciprofloxacin (CIPF) has led to increased resistance in patients and has threatened human health with issues such as digestive disorders, kidney disorders, and liver complications. In order to overcome these concerns, this work introduces a portable electrochemical sensor based on a disposable integrated screen-printed carbon electrode (SPCE) coated with gold nanoparticle-embedded thiol-functionalized Ti₃C₂T_x MXene (AuNPs-S-Ti₃C₂T_x MXene) for simple, rapid, precise, and sensitive quantification of CIPF in milk and water samples. The high surface area and electrical conductivity of AuNPs are maximized thanks to the strong interaction between AuNPs and SH-Ti₃C₂T_x MXene, which can prevent the aggregation of AuNPs and endow larger electroactive areas. Ti₃C₂T_x MXene was synthesized from Ti₃AlC₂ MAX phases, and its thiol functionalization was achieved using 3-mercaptopropyl trimethoxysilane. The prepared AuNPs-S-Ti₃C₂T_x MXene nanocomposite was characterized using FESEM, EDS, XRD, XPS, FTIR, and UV-visible spectroscopy. The electrochemical behavior of the nanocomposite was examined using CV, EIS, DPV, and LSV. The AuNPs-S-Ti₃C₂T_x MXene/SPCE showed higher electrochemical performances towards CIPF oxidation than a conventional AuNPs-Ti₃C₂T_x MXene/SPCE. Under the optimized DPV and LSV conditions, the developed nonenzymatic CIPF sensor displayed a wide range of detection concentrations from 0.50 to 143 μM (DPV) and from 0.99 to 206 μM (LSV) with low detection limits of 0.124 μM (DPV) and 0.171 μM (LSV), and high sensitivities of 0.0863 μA/μM (DPV) and 0.2182 μA/μM (LSV).