Studies Of Electrochemical Biosensors Based On Graphene Functionalized Composites

Biosensor has attracted more and more attention in recent years with lots of superior properties. At the same time, a lot of novel materials were gradually discovered and had been used in constructing biosensor. Enzyme biosensor are especially favoured by researchers because of the specificity and efficient catalytic activity about enzyme. Graphene and its functionalized composites which are new types of carbon nanomaterials possessing perfect physical and chemical properties.This paper mainly prepared some new types of polymer functionalized graphene composites, and then the composites were used to immobilized diamine oxidase,hemoglobin or glucose oxidase to construct biosensor. The electrochemical properties about enzyme in modified electrode were studied. The main content will now be summarized as follows:(1) A new type of nanocomposite was made by mixing with poly(L-lactide)stabilized gold nanoparticles and polyethylene glycol functionalized graphene(r GO-PEG-Au@PLLA). Diamine oxidase(DAO) was the first time immobilizing in r GO-PEG-Au@PLLA to construct a novel biosensor. The direct electron transfer of DAO and related electrochemical properties were achieved by cyclic voltammetry.Amperometry was used to study detection effects of the biosensor to histamine(His)and putrescine(Put), and the results showed pretty good. The linear detection range was from 2 μM to 130 μM toward His with the limit of detection(LOD) of 0.14 μM and a wide linear range of 8 μM to 88 μM with LOD of 3.06 μM toward Put(S/N =3).(2) In this study we have developed a novel biosensor by a simple and environmental-friendly method: hemoglobin(Hb) entrapped in β-cyclodextrin(β-CD)functionalized graphene(r GO) nanocomposite. Hb showed a good electrochemistry behavior in the modified materials. Determination of H2O2 and NO were carried out by amperometry, and the amperometric response of the biosensor varied linearly ranging from 0.029 μM to 6.2 μM toward H2O2 with LOD of 2.2 n M and exhibited a wide linear range of 0.18 μM to 54 μM with LOD of 2.3 n M(S/N = 3).(3) Reduced graphene oxide(r GO) and polyethyleneimine(PEI) were combined and successfully immobilized glucose oxidase. A novel glucose electrochemical biosensor was constructed based on r GO-PEI/GOD modified electrode(r GO-PEI/GOD/GCE). The direct electrochemical behaviors of r GO-PEI/GOD/GCEwere studied by cyclic voltammetry and the results showed that the GOD in the composite membrane showed a pair of well-shaped reversible redox peaks.Meanwhile, the biosensor had a good electrocatalytic capability to glucose, the linear detection range was from 0.04 m M to 12.6 m M with the limit of detection(LOD) of18.8 μM.