In order to construct a robust covalent binding between biomolecule and immobilization platform in biosensor preparation, a novel functional monomer 4-(4,7-di(thiophen-2-yl)-1H-benzo[d]imidazol-2-yl)benzaldehyde (BIBA) was designed and successfully synthesized. After electropolymerization of this monomer, electrochemical and spectroelectrochemical properties were investigated in detail. To fabricate the desired biosensor, glucose oxidase (GOx) was immobilized as a model enzyme on the polymer coated graphite electrode with the help of glutaraldehyde (GA). During the immobilization step, an imine bond was formed between the free amino groups of enzyme and aldehyde group of polymer. The surface characterization and morphology were investigated to confirm bioconjugation by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) at each step of biosensor fabrication. The optimized biosensor shows good linearity between 0.02mM and 1.20mM and a low limit of detection (LOD) of 2.29μM. Kinetic parameters Km(app) and Imax were determined as 0.94mM and 10.91μA, respectively. The biosensor was tested for human blood serum samples.
Keywords: Biosensor; Conducting polymer; Enzyme immobilization; Glucose level; Low detection limit.
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