Detection of E. coli O157:H7 using bacterial molecularly imprinted bipolar electrode and Au@metal-organic framework

A bacterial molecularly imprinted bipolar electrode (BPE) sensor combined with Au@metal-organic frame (Au@MOF) was developed for the E. coli O157:H7 detection. Firstly, dopamine (DA) was mixed with E. coli O157:H7 through an electropolymerization process to form polymer film on the BPE cathode. After bacteria removal, the bacterial molecularly imprinted polydopamine (PDA) film remained on the cathode, exhibiting high specificity for bacterial recognition and binding. Secondly, the E. coli O157:H7 aptamer was modified to the Au@MOF surface by Au-SH covalent bonds. Then, E. coli O157:H7 was present at the cathode, through the specific binding of aptamer to E. coli O157:H7, Au@MOF was assembled to the electrode surface. Finally, 3,3′,5,5′-tetramethylbenzidine/H2O2 (TMB/H2O2) solution was added to the cathode. The Au@MOF exhibited peroxidase-like activity and could catalyze the reduction reaction of TMB/H2O2 system. Due to the electrical neutrality principle of the BPE, the oxidation reaction of [Ru(bpy)3]2+/tripropylamine ([Ru(bpy)3]2+/TPA) system on the anode, generating a distinct Electrochemiluminescence (ECL) signal. The sensor detected E. coli O157:H7 within a concentration range of 1 to 106 CFU mL-1, with a detection limit of 1 CFU mL-1, demonstrating high selectivity and sensitivity. This BPE platform, integrating molecular imprinting and Au@MOF-assisted oxygen reduction, shows significant potential for bacteria detection in various applications.