CTAB@Ti3C2Tx/laser-induced graphene for the detection of veterinary drugs in micro-droplet

The design and construction of novel micro-droplet electrochemical sensor is crucial for the development of electrochemical analysis. The core of micro-droplet electrochemical sensors lies in fabricating effective electrode substrate materials and surface-active materials. MXene have been widely used for electrochemical sensors due to its high conductivity and excellent hydrophilicity. However, MXene-based materials are rarely used for the fabrication of micro-droplet electrochemical sensors. Besides, pure MXene materials often fall short of meeting trace detection requirements for specific substances, which necessitates the surface modification of these MXene materials. This work aims at fabricating novel MXene-based micro-droplet electrochemical sensor for veterinary drug residues detection. In order to achieve this purpose, cationic surfactant cetyltrimethylammonium bromide (CTAB) was intercalated into the interlayers of Ti₃C₂T_x nanosheets, enlarging its interlayer spacing. Meanwhile, CTAB molecules were also bonded on the surface of Ti₃C₂T_x nanosheets through electrostatic adsorption, inducing the assembly of small-sized Ti₃C₂T_x nanosheets into larger ones (CTAB@Ti₃C₂T_x) and endowing Ti₃C₂T_x nanosheets with positively charged surface. Compared with pristine Ti₃C₂T_x nanosheets, the hydrophilicity and adsorption capacity of CTAB@Ti₃C₂T_x were effectively boosted. After then, CTAB@Ti₃C₂T_x were modified on the surface of integrated laser-induced graphene (LIG) electrodes. As a result, CTAB@Ti₃C₂T_x/LIG showed enhanced electrochemical activity and rapid, sensitive micro-droplet electrochemical detection for paracetamol and fenbendazole veterinary drug residues were achieved. Finally, the constructed CTAB@Ti₃C₂T_x/LIG micro-droplet electrochemical sensor was employed for the detection of paracetamol and fenbendazole in pork and milk samples, exhibiting satisfactory detection accuracy.