Electrochemical myoglobin biosensor based on carbon ionic liquid electrode modified with Fe3O4@SiO2 microsphere

Abstract

In this paper, a Fe3O4@SiO2 core-shell structure microsphere was synthesized and used to investigate the direct electron transfer of myoglobin (Mb) with a 1-butylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE) as the substrate electrode. The mixture of Mb and Fe3O4@SiO2 microsphere could form an organic–inorganic composite, which was immobilized on the surface of CILE with a chitosan (CS) film. Cyclic voltammetric experiments indicated that a pair of well-defined quasi-reversible redox peaks appeared on CS/Mb-Fe3O4@SiO2/CILE with the formal peak potential (E0′) located at −0.31 V (vs. saturated calomel electrode), which was corresponded to the electroactive center of Mb heme Fe(III)/Fe(II) redox couples. Direct electrochemical behaviors of Mb in CS-Fe3O4@SiO2 composite film were carefully investigated with the electrochemical parameters calculated. The CS/Mb-Fe3O4@SiO2/CILE showed good electrocatalytic behaviors to the reduction of trichloroacetic acid in the concentration range from 0.2 to 11.0 mmol L−1 with the detection limit of 0.18 mmol L−1 (3σ). Based on CS/Mb-Fe3O4@SiO2/CILE, a new third-generation reagentless electrochemical biosensor was constructed with higher sensitivity and reproducibility.