Biosensors cyclic voltammetry

Procedure-Electron-Mediated Biosensor. 1,3-DAB was electropolymerized onto the graphite from a 3 mM solution in phosphate buffer using cyclic voltammetry. The potential was cycled from 0.00 V to +0.80 V and back to 0.00 V (vs SCE) at 5 mV/s for twelve scans. l,r-dimethylferrocene (1,1 -DMF) was adsorbed onto an inverted electrode. Three successive drops of a saturated solution (10 pL each) were added to the surface and each was allowed to air dry before applying the next drop. The electrode was rinsed with water after application of each drop. 

In this chapter, we review the recent progress in the development of different metal oxide nanoparticles with various shapes and size for fabrication of biosensors. The development of metal oxide nanomaterials surface film for direct electron exchange between electrodes and redox enzymes and proteins will be summarizing. The electrochemical properties, stability and biocatalytic activity of the proposed biosensors will be discussed. The biocompatibility of the metal oxide nanomaterials for enzymes and biomolecules will be evaluated. We will briefly describe some techniques for the investigation of proteins and enzymes when adsorbed to the electrode surfaces. Cyclic voltammetry, impedance spectroscopy, UV-visible spectroscopy and surface imaging techniques were used for surface characterization and bioactivity measuring. 

As shown the thickness of these nanosheets is about 20 nm. There are numerous nanoscaled cavities on the surface of ZnO microspheres. The size of the cavity is about several hundred nanometers, which is accessible for the enzymes to sequester in the cavities or bind on the surface. Furthermore the cavities may provide a protective microenvironment for the enzymes to retain their enzymatic stability and activity by limiting the conformational change and unfolding of the entrapped enzyme. The FTIR spectra of hemoglobine (Hb) and Hb-ZnO- nafion composite film is shown in Fig.4B. The similarities of two spectra suggested that Hb retained the essential features of its native secondary structure in ZnO nafion composite film, and revealed the excellent biocompability of ZnO nafion composite film. Cyclic voltammetry response of the biosensor at different scan rates was shown in Fig.5. 

Due to high biocompability and large surface are of cobalt oxide nanoparticles it can be used for immobilization of other biomolecules. Flavin adenine FAD is a flavoprotein coenzyme that plays an important biological role in many oxidoreductase processes and biochemical reactions. The immobilized FAD onto different electrode surfaces provides a basis for fabrication of sensors, biosensors, enzymatic reactors and biomedical devices. The electrocatalytic oxidation of NADH on the surface of graphite electrode modified with immobilization of FAD was investigated [276], Recently we used cyclic voltammetry as simple technique for cobalt-oxide nanoparticles formation and immobilization flavin adenine dinucleotide (FAD) [277], Repeated cyclic voltammograms of GC/ CoOx nanoparticles modified electrode in buffer solution containing FAD is shown in Fig.37A. 

Liao et al. have applied magnetic nanoparticles for development of a reagentless disposable amperometric ethanol biosensor. The electrochemical characteristics of modified electrode investigated by cyclic voltammetry, have been found as linearity (1-9.0 mM), sensitivity (0.61pAmM 1) and response (20 s) [102],... 

Patolsky, K, Zayats, M., Katz, E., and Willner, I. (1999) Precipitation of an insoluble product on enzyme monolayer electrodes for biosensor applications Characterization by faradaic impedance spectroscopy, cyclic voltammetry, and microgravimetric quartz crystal microbalance analyses. Anal. Chem. 71, 3171-3180... 

In order to immobilize enzymes in conducting polymers to fabricate biosensors, the electrochemical synthesis of polypyrrole films was studied under different conditions. It was found that the size and morphology of polypyrrole films synthesized using cyclic voltammetry were affected by the concentration of the supporting electrolyte at a scan potential range between 0.0 and 1.0 V (vs. SCE), and at a scan rate of 48 mV s [47]. The diameters of particles prepared in a solution containing 0.10 M pyrrole and 0.10 M NaCl... 

A very recent example of the use of this redox probe in an aptamer-based biosensor was published by Kim et al. [33]. An electrochemical biosensor for ox3d etracycline detection was developed using ssDNA aptamer immobilized on gold interdigitated array (IDA) electrode chip (Fig. 2.7). Cyclic voltammetry and square wave voltammetry were used to measure the current at the electrode chip... 

This study describes initial electrochemical experiments, aimed at the development of an amperometric glucose biosensor using ferrocene as the electron mediator, incorporated into an oriented polypyrrole LB film. A variety of monolayer samples were prepared for cyclic voltammetry (CV) studies to determine if the ferrocene was detectable electrochemically in such a configuration. This was an important criterion,as... 

Beyond an insight into the ease with which compounds can be oxidized or reduced by measuring the formal potential, cyclic voltammetry can be used to determine the rate of electron transfer across the electrode/solution or electrode/film interface. Optimizing the rate of heterogeneous electron transfer is important for technological applications ranging from the analysis of metals in polymers, foods, and cosmetics to the development of biosensors and molecular electronic devices. 

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