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 0.01 mM to 1 mM H2O2 and 0.1 mM to 1.4 mM glucose, with high sensitivities of 4340.6 mu A mM(-1) cm(-2) and 1074.6 mu A mM(-1) cm(-2), respectively. The relative standard deviations (RSD) were 5.4% for H2O2 detection and 5.8% for glucose detection. The true detecting range was 0.4-40 mM for H2O2 and 4-56 mM 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. (C) 2012 Elsevier B.V. All rights reserved.