Reusable sensor based on high magnetization carboxyl-modified graphene oxide with intrinsic hydrogen peroxide catalytic activity for hydrogen peroxide and glucose detection

We propose a new strategy to improve the enzyme stability, construction and sensitivity of a multifunctional sensor. An exfoliated graphene oxide sheet with carboxyl-long-chains (GO-CLC) was prepared in one step from primitive graphite via Friedel-Crafts acylation. Magnetic nanoparticles, glucose oxidase (GOD) and poly[aniline-co-N-(1-one-butyric acid) aniline] (SPAnH) were then incorporated to form an electrochemical film (SPAnH-HMGO-CLC-GOD) for the detection of hydrogen peroxide (H₂O₂) and glucose. The GO and Fe₃O₄ have intrinsic hydrogen peroxide catalytic activity and the activity will be enhanced by the combination of SPAnH coating and induces an amplification of electrochemical reduction current. This response can be used as a glucose sensor by tracing the released H₂O₂ after enzymatic reaction of bound GOD. Our sensor was linear within the range from 0.01mM to 1mM H₂O₂ and 0.1mM to 1.4mM glucose, with high sensitivities of 4340.6μAmM^-1cm^-2 and 1074.6μAmM^-1cm^-2, respectively. The relative standard deviations (RSD) were 5.4% for H₂O₂ detection and 5.8% for glucose detection. The true detecting range was 0.4-40mM for H₂O₂ and 4-56mM for glucose, which multiplied by 40-fold of dilution. This sensor based on the catalysis of organic SPAnH and the enzymatic activity of GOD can be used for both H₂O₂ and glucose sensing in potential clinical, environmental and industrial applications.