Design of a polypyrrole MIP-SAW sensor for selective detection of flumequine in aqueous media. Correlation between experimental results and DFT calculations

Abstract

A shear horizontal surface acoustic wave sensor (SH-SAW) operating at 104 MHz was functionalized with a polypyrrole (PPy) molecularly imprinted polymer (MIP) for selective detection of flumequine (FLU) in aqueous media. In order to prevent the formation of FLU complexes with the gold sensing area of the SH-SAW sensor, a thin blocking polypyrrole layer was deposited by chronoamperometry before the MIP electrochemical deposition. The detection limit of the designed sensor was of the order of 1 μM and the sensitivity was estimated to be at 9.36 ± 0.39° mM⁻¹. Selectivity tests were made with levofloxacin (LEVO), an interfering fluoroquinolone antibiotic. Results indicate that the designed PPy-MIP recognition layer is selective of flumequine. Quantum chemical calculations, based on density functional theory (DFT), have permitted us to highlight the importance of the PPy blocking layer, on the one hand, and the nature of interactions between the polypyrrole matrix and FLU and LEVO analytes, on the other hand.