Preparation and Application of Mediator‐Free H₂O₂ Biosensors of Graphene‐Fe₃O₄ Composites

Abstract

Graphene-Fe 3 O 4 (G-Fe 3 O 4 ) composites were prepared with a solvothermal method for the immobilization of horseradish peroxidase (HRP) to construct a mediator-free H 2 O 2 biosensor. The morphology and structure of the GFe 3 O 4 composites were analyzed by TEM, SEM, and XRD. Chitosan (CH) was utilized to disperse the composites, and the mixture of CH, G-Fe 3 O 4 and HRP was spin-coated on an indium tin oxide (ITO) electrode to form a biocomposites film. Electrochemical impedance spectroscopy (EIS) and cyclic voltammograms (CV) demonstrated the fast electron transfer process between HRP and the electrode. The resulted H 2 O 2 biosensor exhibited a rapid response upon the addition of H 2 O 2 , a high sensitivity of 132 mA mM À1 cm À2 and a low detection limit of 6 10 À7 M. The linear range of the biosensor is from 5 10 À6 to 3.81 10 À3 M (r = 0.997). Such interesting G-Fe 3 O 4 composites with easy preparation and low cost can provide a novel matrix for enzyme immobilization to construct biosensors with higher performance.

Design, Synthesis, and Characterization of Graphene–Nanoparticle Hybrid Materials for Bioapplications

“…Graphene–metal oxide nanoparticle composites (e.g., ZnO, 57 TiO 2 , 58 Fe 3 O 4 , 59 SnO 2 , 60 ) are, by far, the most common hybrids synthesized using the hydrothermal method. Specifically, metal oxide nanoparticles can provide the graphene–metal oxide nanoparticle hybrids with a number of advantages such as a higher capacitance, which depends on the nanoparticle structure, size, and crystallinity, while suppressing agglomeration and the restacking of graphene.…”

An amperometric H2O2 biosensor based on hemoglobin nanoparticles immobilized on to a gold electrode

“…H 2 O 2 is one of the reactive oxygen species (ROS) amongst others like superoxide anion (O 2 •− ), hydroxyl radical (OH • ), hydroxyl ion (OH − ). The higher concentration of H 2 O 2 is associated with diabetes, atherosclerosis, and ageing, as it generates free hydroxyl radicals, which cause oxidative damage to the tissue components such as lipids and proteins beside DNA [2,3]. For the measurement of H 2 O 2 in biological fluids, several sensitive methods based on horseradish peroxidase (HRP) and artificial substrates (such as Amplex Red and 3,5,3′,5′-tetramethylbenzidine) or on ferrous oxidation in the presence of xylenol orange (FOX) have been developed [4].…”

Electrochemical Sensors Using Two‐Dimensional Layered Nanomaterials

“…To these goals, several graphene‐based electrochemical sensors have been developed for sensitive H 2 O 2 detection 42. Dong’s group first reported that chemically reduced graphene oxide (GO) possessed superior electrocatalytic activity toward H 2 O 2 43, 44. Liu et al.…”