Electrochemical paper-based sensor based on molecular imprinted polymer and nitrogen-doped graphene for tetracycline determination

In this work, an electrochemical paper-based analytical device (ePAD) based on molecular-imprinted polymer (MIP) and nitrogen-doped graphene (NG) was developed for sensitive electrochemical detection of tetracycline in wastewater. The NG was in-situ synthesized on the paper-based screen-printed carbon electrode (pSPCE) by potentiostatic method to improve the conductivity of the sensor. Subsequently, the MIP were electropolymerized on NG using o-phenylenediamine (oPD) as a functional monomer and tetracycline (TC) as template molecule by cyclic voltammetry (CV) to deliver the specific recognition of TC. The electrode modification process was highly controllable, and the detection efficiency was improved. The electrochemical properties of MIP/NG/ePAD were evaluated by CV, differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the fabricated ePAD sensor showed a good linear relationship with TC concentration ranging from 5 x 10(-9) to 1 x 10(-5) mol/L with a correlation coefficient (R-2) of 0.995 and a detection limit of 3.29 x 10(-9) mol/L. The ePAD sensor was successfully applied to TC detection in real water samples with satisfied recoveries from 94.0 % to 106.9 %. The low-cost, portable, high specificity, and reliable ePAD sensor proposed here has promising potential for application in point-of-care testing (POCT) in environmental monitoring.