A novel strategy to improve the sensitivity of antibiotics determination based on bioelectrocatalysis at molecularly imprinted polymer film electrodes

A new strategy for the sensitive detection of kanamycin (KA) and other antibiotics based on molecularly imprinted polymer (MIP) and bioelectrocatalysis was developed in the present study. The KA-polypyrrole MIP films were electropolymerized on the surface of pyrolytic graphite (PG) electrodes, with pyrrole (PY) serving as the monomer and KA as the template. Because KA is electro-inactive, electroactive K 3 [Fe(CN) 6 ] was used as the probe in the cyclic voltammetric (CV) measurements. The difference of the CV reduction peaks of K 3 [Fe(CN) 6 ] at electrodes between the MIP films after KA removal and KA-rebinding MIP films could thus be used to determine KA quantitatively. When horseradish peroxidase (HRP) and H 2 O 2 were added into the testing solution, the detection sensitivity of the system was greatly amplified because the electrochemical reduction of H 2 O 2 could be catalyzed by HRP and mediated by K 3 [Fe(CN) 6 ]. With the bioelectrocatalysis amplification, the limit of detection (LOD) for KA fell as low as 28   nM, approximately two orders of magnitude lower than that for the MIP films in the absence of enzymatic catalysis. The strategy demonstrated the generality. Not only KA but also other antibiotics, such as oxytetracycline (OTC), could be determined by this method. More significantly, in addition to the K 3 [Fe(CN) 6 ]–HRP–H 2 O 2 system, other bioelectrocatalysis systems, such as Fc(COOH) 2 –GOD–glucose (Fc(COOH) 2 =ferrocenedicarboxylic acid, GOD=glucose oxidase), could also be used to amplify the CV signal and realize the sensitive detection of KA for the MIP film system, thereby illustrating the great potential and prospects of the strategy.