Defect-rich Co,N-doped TiCTx/C/poly (3,4-ethylenedioxy thiophene) molecularly imprinted sensor for ultrasensitive electrochemical detection of gatifloxacin.

The molecular imprinting electrochemical sensors (MIECS) currently face issues such as low sensitivity and stability to be improved. This study innovatively combines ZIF-67/TiCTx, treated at high temperature, with molecular imprinting technology to construct a MIECS with excellent stability and high sensitivity. First, size-controllable ZIF-67 was grown in situ on TiCTx, and after high-temperature treatment, Co,N-TiCTx/C was obtained. This was combined with proton-conductive poly(3,4-ethylenedioxythiophene) (PEDOT) to build the MIECS (Co,N-TiCTx/C/PEDOT/MIP/GCE). A series of structural characterization and electrochemical tests revealed that the synergistic effect of the abundant defect structures and the excellent proton conductivity of PEDOT significantly enhanced the electrochemical redox activity. The modified electrode demonstrated outstanding electrochemical performance, including an ultra-high electrochemical active surface area and selective recognition of gatifloxacin (GAT) through the imprinted cavities. Further investigation of the sensor's electrochemical detection performance for GAT showed that the fabricated sensor has high sensitivity, good stability, and excellent selectivity. Experimental results indicated that the sensor has a wide linear response range (0.005-50 μM), a low detection limit (2 nM), and test RSD values are all less than 5 % in honey, milk and lake water, and reliable recoveries were achieved in comparison with standard chromatographic methods. Highlight its potential for practical antibiotic monitoring applications.