| Electrochemical biosensors have some outsanding advantages includingexcellent selectivity, high sensitivity，rapid response，easy to be miniaturized andautomation. Therefore, they have potential applications in biology, environmentalmonitoring, chemical measurements in the agriculture and food industry.Nano-materials as new material are attractive in the developement of biosensorsdue to their novel optical, electrical, catalytic properties and favorablebiocompatibility. Nano-materials display unique properties such as catalyticproperties, large area, biological compatilities and so on. With the introduction ofnanomaterials, the performance of biosensor has a greatly improve-ment.In this paper, we developed novel electrochemical biosensors for selective andsensitive analytical applications based on functionalized nanomaterials. We providedthe background on the development and applications of nanomaterials. And then wesummarized recent progress on nanomaterials based electroehemieal biosensors,including analytical applications for different targets. Finally, we summarized theexperimental ideas and the research purposes of this thesis. In this thesisFe304-reduced graphene oxide (Fe3C>4-RGO)，carbon nanotubes (CNTs) andmanganese tetraoxide (M113O4) were applied for the fabrication of electrochemicalbiosensors. The major contents in this thesis are described as fllows:(1) Alfatoxin produced by Aspergillus flavus and Aspergillus parasiticus arecommonly found in olive and its derivatives. Aflatoxin Bi (AFBi) is apredominant toxin detected abundantly and has been implicated in the etiology ofhuman hepatocellular carcinoma. This study proposes a sensitive and convenientelectrochemical impedance spectroscopy (EIS) method for determining AFBi byMWCNTs/RTIL composite films-based immunosensor. The calibration curves forAFBi was linear in the ranges of0.1-10ng mL"1with the limit of detection (LOD)01.01ng mL". The presence of MWCNTs warrant fast electron transfer, and theionic liquid provides a benign microenvironment for antibody. The experimentalparameters, such as pH and incubating time，have been investigated and optimized.Furthermore, the detection of AFBi is presented to test this method after extracted from olive oils. It can be anticipated that this method would be used for thedetection of AFBi in various agriculture products and vegetable oils.(2)An electrochemical sensing platform was developed based on glucose oxidase(G0x)/Fe304-reduced graphene oxide (Fe304-RG0) nanosheets loaded on themagnetic glassy carbon electrode (MGCE). With the advantages of the magnetismand biocompatibility of the Fe3C>4-RGO nanosheets, the nanocomposites could befacilely adhered to the electrode surface by magnetically controllable assembling.Electrochemical methods containing cyclic voltammetry (CV) and amperometrywere used to study the direct redox reactions and electrocatalytic behaviors ofGOx immobilized into the nanocomposites. The biosensor exhibited goodelectrocatalytic activity, high sensitivity and selectivity. The current response islinear over glucose concentration ranging from0.05to1.5mM with a lowdetection limit of0.15Meanwhile, validation of the applicability of thebiosensor was carried out by determining glucose in serum samples. The proposedprotocol is simple, inexpensive and convenient, which shows great potential inbiosensing application.(3)The preparation of a non-enzymatic H2O2biosensor was developed by casting theMnsOVChi on the glassy carbon electrode. Manganese oxides (MnOx) are of greatimportance in catalysis, electrochemistry, ion-exchange materials, magnetite, andbatteries, among other areas, Mri304is widely used as catalysts and electrodematerials. MnaO^Chi composite was fabricated as a lfexible biosensor fornonenzymatic determination of H2O2and cystine. The Mn304/Chi-based biosensorachieved high sensitivity, large linear range and low detection limit for thedetection of both analytes, due to the high electrocatalytic activity of thenanostructured M113O4network. |
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