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Biosensors amperometric

Electrochemical sensor fabrication has dominated the analytical application of polymers. In some sensors the polymer film acts as a membrane for the preconcentration of ions or elements before electrochemical detection. Polymers also serve as materials for electrode modification that lower the potential for detecting analytes. In addition, some polymer films function as electrocatalytic surfaces. Using a polymer in biosensors is a very rapidly developing area of electroanalytical chemistry. Polymeric matrix modifiers have been applied as diffusional barriers in constructing not only sensitive amperometric biosensors, but also electrochemical sensors that apply potentiometric, conductimetric, optical, and gas-sensing transducer systems. The principles, operations, and application of potentiometric, conductimetric, optical and gas sensors are described in Refs. 13, 39-41. In this chapter, we focus mainly on amperometric biosensors based on redox enzymes. [Pg.300]

An effective means of achieving chemical selectivity is to modify the electrode with either a synthetic catalyst or an enzyme. Let us first consider the ampero- [Pg.221]

In principle, there is no requirement on how fast the electrochemical reaction should be because, as we have seen, it is usually possible to apply the working potential E at which the kinetics of the charge transfer are fast. The origin of selectivity is in the enzymatic reaction. [Pg.222]

In Fig. 2.10, the boundary between the enzyme-containing layer and the transducer has been considered as having either a zero or a finite flux of chemical species. In this respect, amperometric enzyme sensors, which have a finite flux boundary, stand apart from other types of chemical enzymatic sensors. Although the enzyme kinetics are described by the same Michaelis-Menten scheme and by the same set of partial differential equations, the boundary and the initial conditions are different if one or more of the participating species can cross the enzyme layer/transducer boundary. Otherwise, the general diffusion-reaction equations apply to every species in the same manner as discussed in Section 2.3.1. Many amperometric enzyme sensors in the past have been built by adding an enzyme layer to a macroelectrode. However, the microelectrode geometry is preferable because such biosensors reach steady-state operation. [Pg.223]

There are many possibilities that can be implemented in enzymatic amperometric biosensors. Enzymatic schemes including several enzymes in one layer or multiple enzymatic layers in series can be used. If the cosubstrates are involved, it may be possible to oxidize or reduce one of them as well. [Pg.223]

The enzyme can be incorporated into an amperometric sensor in a thick gel layer, in which case the depletion region due to the electrochemical reaction is usually confined within this layer. Alternatively, enzyme can be immobilized at the surface of the electrode or even within the electrode material itself, in which case the depletion region extends into the solution in the same way as it would for an unmodified electrode. In the latter case, the enzyme can then be seen as a true electrocatalyst that facilitates the interfacial electron transfer, which would otherwise be too slow. The general principles of the design and operation of these biosensors is illustrated on the example of the most studied enzymatic sensor, the glucose electrode (Fig. 2.14, Section 2.3.1). [Pg.223]

In configuration A, ET from the enzyme redox center to the electrode is made possible by addition of a diffusional electron mediator that rapidly shuttles the electron (s) to and from the electrode. In configuration B, redox labels are covalently tethered to the enzyme surface and relay the electrons to and from the electrode. [Pg.182]

In configuration C, the enzyme is immobilized in a cross-linked redox polymer adsorbed onto the electrode surface. [Pg.183]


Schematic showing the reactions by which an amperometric biosensor responds to glucose. Schematic showing the reactions by which an amperometric biosensor responds to glucose.
This experiment describes the use of a commercially available amperometric biosensor for glucose that utilizes the enzyme glucose oxidase. The concentration of glucose in artificial... [Pg.535]

Commercially available kits for monitoring blood-glucose use an amperometric biosensor incorporating the enzyme glucose oxidase. This experiment describes how such monitors can be adapted to the quantitative analysis of glucose in beverages. [Pg.535]

Abass and colleagues developed an amperometric biosensor for NHA that uses the enzyme glutamate dehydrogenase to catalyze the following reaction. [Pg.539]

Describe the major problems encountered in the detection of the NADH product of dehydrogenase-based amperometric biosensors. Discuss a common approach to circumvent these problems. [Pg.202]

Wang, B.Q. and Dong, S.J. (2000) Sol-gel-derived amperometric biosensor for hydrogen peroxide based on methylene green incorporated in Nafion film. Talanta, 51, 565—572. [Pg.109]

In AChE-based biosensors acetylthiocholine is commonly used as a substrate. The thiocholine produced during the catalytic reaction can be monitored using spectromet-ric, amperometric [44] (Fig. 2.2) or potentiometric methods. The enzyme activity is indirectly proportional to the pesticide concentration. La Rosa et al. [45] used 4-ami-nophenyl acetate as the enzyme substrate for a cholinesterase sensor for pesticide determination. This system allowed the determination of esterase activities via oxidation of the enzymatic product 4-aminophenol rather than the typical thiocholine. Sulfonylureas are reversible inhibitors of acetolactate synthase (ALS). By taking advantage of this inhibition mechanism ALS has been entrapped in photo cured polymer of polyvinyl alcohol bearing styrylpyridinium groups (PVA-SbQ) to prepare an amperometric biosensor for... [Pg.58]

K. Rekha, M.D. Gouda, M.S. Thakur, and N.G. Karanth, Ascorbate oxidase based amperometric biosensor for organophosphorous pesticide monitoring. Biosens. Bioelectron. 15, 499-520 (2000). [Pg.74]

C. la Rosa, F. Pariente, L. Hernandez, and E. Lorenzo, Determination of organophosphorus and car-bamic pesticides with an acetylcholinesterase amperometric biosensor using 4-aminophenyl acetate as substrate. Anal. Chim. Acta 295, 273-282 (1993). [Pg.75]

E.V. Gogol, G.A. Evtugyn, J.L. Marty, H.C. Budnikov, and V.G. Winter, Amperometric biosensors based on Nafion coated screen-printed electrodes for the determination of cholinesterase inhibitors. Talanta 53, 379-389 (2000). [Pg.75]

M.A. Sirvent, A. Merkoci, and S. Alegret, Pesticide determination in tap water and juice samples using disposable amperometric biosensors made using thick-film technology. Anal. Chim. Acta 442, 35-44 (2001). [Pg.75]

P.R.B. de O Marques, G.S. Nunes, T.C.R. dos Santos, S. Andreescu, and J.L. Marty, Comparative investigation between acetylcholinesterase obtained from commercial sources and genetically modified Drosophila melanogaster application in amperometric biosensors for methamidophos pesticide detection. Biosens. Bioelectron. 20, 825-832 (2004). [Pg.78]

A.A. Ciucu, C. Negulescu, and R.P. Baldwin, Detection of pesticides using an amperometric biosensor based on ferophthalocyanine chemically modified carbon paste electrode and immobilized bienzymatic system. Biosens. Bioelectron. 18, 303-310 (2003). [Pg.78]

J. Newman, S. White, I. Tothill, and A.P. Turner, Catalytic materials, membranes, and fabrication technologies suitable for the construction of amperometric biosensors. Anal. Chem. 67, 4594-4599 (1995). [Pg.91]

Q. Chi and S. Dong, Amperometric biosensors based on the immobilization of oxidases in a Prussian blue film by electrochemical codeposition. Anal. Chim. Acta 310, 429-436 (1995). [Pg.91]

L. Mao, E Xu, Q. Xu, and L. Jin, Miniaturized amperometric biosensor based on xanthine oxidase for monitoring hypoxanthine in cell culture media. Anal. Biochem. 292, 94—101 (2001). [Pg.208]

A.A. Karyakin, E.E. Karyakina, and L. Gorton, Prussian Blue based amperometric biosensors in flow-injection analysis. Talanta 43, 1597-1606 (1996). [Pg.454]

A.A. Karyakin, O.V. Gitelmacher, and E.E. Karyakina, A high-sensitive glucose amperometric biosensor based on Prussian blue modified electrodes. Anal. Lett. 11, 2861—2869 (1994). [Pg.459]

J. Wang, P.V.A. Pamidi, and D.S. Park, Sol-gel-derived metal-dispersed carbon composite amperometric biosensors. Electroanalysis 9, 52-55 (1997). [Pg.459]

S. Milardovic, I. Kruhak, D. Ivekovic, V. Rumenjak, M. Tkalcec, and B.S. Grabaric, Glucose determination in blood samples using flow injection analysis and an amperometric biosensor based on glucose oxidase immobilized on hexacyanoferrate modified nickel electrode. Anal. Chim. Acta 350, 91-96... [Pg.460]

S. Milardovic, Z. Grabaric, M. Tkalcec, and V. Rumenjak, Determination of oxalate in urine using an amperometric biosensor with oxalate oxidase immobilized on the surface of a chromium hexacyanoferrate-modified graphite electrode. J. AOAC Int. 83,1212—1217 (2000). [Pg.461]

Other enzymes have also been immobilized on CNTs for the construction of electrochemical biosensors. Deo et al. [115] have described an amperometric biosensor for organophosphorus (OP) pesticides based on a CNT-modified transducer and OP hydrolase, which is used to measure as low as 0.15 pM paraoxon and 0.8 pM parathion with... [Pg.503]

P.P. Joshi, S.A. Merchant, Y. Wang, and D.W. Schmidtke, Amperometric biosensors based on redox polymer-carbon nanotube-enzyme composites. Anal. Chem. 77, 3183—3188 (2005). [Pg.522]


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