Electrochemical Sensor Based on Molecularly Imprinted Polymer for the Detection of Cefalexin

In this study, a new electrochemical sensor was developed for the detection of cefalexin (CFX), based on the use of a molecularly imprinted polymer (MIP) obtained by electro‒polymerization in an aqueous medium of indole-3-acetic acid (I3AA) on a glassy carbon electrode (GCE) and on boron-doped diamond electrode (BDDE). The two different electrodes were used in order to assess how their structural differences and the difference in the potential applied during electrogeneration of the MIP translate to the performances of the MIP sensor. The quantification of CFX was performed by using the electrochemical signal of a redox probe before and after the rebinding of the template. The modified electrode was characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The influence of different parameters on the fabrication of the sensor was tested, and the optimized method presented high selectivity and sensitivity. The MIP-based electrode presented a linear response for CFX concentration range of 10 to 1000 nM, and a limit of detection of 3.2 nM and 4.9 nM was obtained for the BDDE and the GCE, respectively. The activity of the sensor was successfully tested in the presence of some other cephalosporins and of other pharmaceutical compounds. The developed method was successfully applied to the detection of cefalexin from real environmental and pharmaceutical samples.