Sensors immuno

FIGURE 5.10 An equivalent circuit representing the interfacial features of an electrochemical immuno-sensor in the presence of a redox probe. 

Immunoaffinity chromatography (IAC), 6 400—402 12 137, 145 Immunoanalyzers, automated, 14 150 Immunoassay(s), 14 135-159. See also Immunoassay- DNA probe hybrid assays Immunoassay methods Immuno(bio)sensors antibody-antigen reaction, 14 136-138 basic technology in, 14 138-140 chemiluminescent, 14 150-151 classification of, 14 140-153 design of, 14 139-140 enzyme, 14 143-148 fluorescence, 14 148-150 highly specific, 14 153 historical perspective on, 14 136 microarrays and, 14 156—157 microfluidics in, 26 968—969 monoclonal versus polyclonal antibodies in, 14 152-153... 

G. Gauglitz, Opto-Chemical and Opto-Immuno Sensors, Sensor Update Vol. 1, VCH Verlagsgesellschaft, Weinheim (1996). 

Figure 3.30 — (A) Flow-injection manifold for implementation of immuno-sensors. (B) Scheme of a thin-layer flow-through immunosensor. (Reproduced from [220] with permission of the American Chemical Society).

Based on these chemosensors, biosensors can be set up such as glucose or H2O2 sensors. In this case the appropriate biological compound (glucose oxidase or catalase) must be immobilized on the chemosensor. Different optical sensors are also used as transducer elements for the production of biosensors, especially of immuno-sensors. Here the affinity component is immobilized on the tip of the fiber and all available immuno-sensing assays can be performed using this transducer element. Since these sensors cannot be sterilized and used for on-line monitoring in a bioprocess we refer to other publications [25-27]. 

Very few immunosensors are commercially available. The commercial immunosensors are either the detector or bioanalyzer types. The PZ 106 immunosensor from Universal Sensors Inc. (New Orleans, LA) has been used as a detector to measure antibody-antigen reaction. Ohmicron (Newtown, PA) developed a series of pesticide immuno-bioanalyzers that have been used in field tests. Pharmacia Biosensor USA (Piscataway, NJ) recently introduced BIAcore immunodetection system. A combination of a unique flow injection device and surface plasmon resonance (SPR) detection technique provides a real time analysis. A carboxylmethyldextran layer added to plasmon generating gold film is a hydrophobic, activatable, and flexible polymer that provides high antibody and low non-specific bindings. System demonstration at the Institute of Food Technologists (IFT) 1994 meeting in Atlanta drew attention of food scientists. It should easily be adapted for food protein characterization. 

Chapters 1 to 5 deal with ionophore-based potentiometric sensors or ion-selective electrodes (ISEs). Chapters 6 to 11 cover voltammetric sensors and biosensors and their various applications. The third section (Chapter 12) is dedicated to gas analysis. Chapters 13 to 17 deal with enzyme based sensors. Chapters 18 to 22 are dedicated to immuno-sensors and genosensors. Chapters 23 to 29 cover thick and thin film based sensors and the final section (Chapters 30 to 38) is focused on novel trends in electrochemical sensor technologies based on electronic tongues, micro and nanotechnologies, nanomaterials, etc. 

This principle is applied for the potential development in the EPMEs and for obtaining the intensity of the current in amperometric immuno-sensors. For the enantioselective, potentiometric electrodes, it is necessary to find a molecule with a special architecture that can accommodate the enantiomer. In this regard, cyclodextrins and their derivatives, maltodextrins, antibiotics and fullerenes and their derivatives were proposed [17-52]. 

F. Darain, S.-U. Park and Y.-B. Shim, Disposable amperometric immuno-sensor system for rabbit IgG using a conducting polymer modified screen-printed electrode, Biosens. Bioelectron., 18 (2003) 773-780. 

E. Crowley, C. O Sullivan and G.G. Guilbault, Amperometric immuno-sensor for granulocyte-macrophage colony-stimulating factor using screen-printed electrodes, Anal. Chim. Acta, 389 (1999) 171-178. 

S. Centi, S. Laschi and M. Franekand M. Mascini, A disposable immuno-magnetic electrochemical sensor based on functionalised magnetic beads and carbon-based screen-printed electrodes (SPCEs) for the detection of polychlorinated biphenyls (PCBs), Anal. Chim. Acta, 538 (2005) 205-212. 

This detector is based on the collective oscillations of the free electron plasma at a metal surface. Typically a prism is coated with a metal film and the film coated with a chemically selective layer. The surface is illuminated by a laser and the amount of material adsorbed by the coating affects the angle of the deflected beam. This platform is theoretically similar in sensitivity to a quartz crystal microbalance. This is another platform whose selectivity is based on the coating. The typical coating is using bound antibodies thus, this device becomes a platform for immuno-sensors (12). 

Another advantage offered by ICPs is that the eleetroehemieal synthesis allows the direet deposition of the polymer on the electrode surfaee, while simultaneously trapping the protein molecules. It is thus possible to control the spatial distribution of the immobilized enzymes, the film thickness and modulate the enzyme activity by changing the state of the polymer. Because of these ICPs have been used in the fabrication of biosensors in various fields such as Health eare, immuno sensors, DNA sensors, environmental monitoring, and food analysis. 

An immuno sensor for determining specific proteins uses a liquid antigen containing cardiolipin, phosphatidyl choline, and cholesterol immobilized onto an acetyl cellulose membrane. The membrane-bound antigen retains immunological reactivity to Wasserman antibody. The asymmetrical potentitil is dependent on the concentration of the antibody (319, 320). 

Obenauer-Kutner, L.J. Jacobs, S.J. Kolz, K. Tobias, L.M. Bordens, R.W.A. A highly sensitive electrochemiluminescence immunoassay for interferon alfa-2b in human serum. J. Immunol. Meth. 1997, 206 (1-2), 25-33. Rabbany, S.Y. Donner, B.L. Ligler, F.S. Optical immuno-sensors. Crit. Rev. Biomed. Eng. 1994, 22 (5-6), 307-346. Wink, T. van Zuilen, S.J. Bull, A. van Bennekom, W.P. Liposome-mediated enhancement of the sensitivity in immunoassays of proteins and peptides in surface plasmon resonance spectrometry. Anal. Chem. 1998, 70 (5), 827-832. Gaudin, V. Pavy, M.-L. Determination of sulfamethazine in milk by biosensor immunoassay. J. AOAC Int. 1999, 82 (6), 1316-1320. 

The properties of high specificity and a wide applicability with many analytes have led to the widespread use of immunoanalytical techniques. The benefits of electrochemical sensors include technical simplicity, speed, and convenience via direct transduction to electronic equipment. Combining these two systems offers the possibility of a convenient assay technique with high selectivity. Because of the complexity of immunoassay methods, such devices have not yet found widespread use. Nevertheless, electrochemical immuno-sensors offer the potential for fast, simple, cost-effective analysis of many... 

Stefan and Bokretsion [84] constructed lately an amperometric immuno-sensor based on diamond paste (diamond powder and paraffin oil) impregnated with anti-azidothymidine antibody for the assay of azidothy-midine (AZT, an approved and widely used antiretroviral drug for the treatment of human immunodeficiency virus infection) in its pharmaceutical formulations. The potential used for azidothymidine assay was -1-240 mV vs. Ag/AgCl electrode. 

Suleiman and Xu [128] described a novel reusable amperometric immuno-sensor for the determination of cocaine. Horseradish peroxidase and benzoylecgonine-antibody were co-immobilized on a chemically activated affinity membrane, which was then mounted over the tip of an oxygen electrode. The enzymatic electrocatalytic current response to the substrate is inhibited by the association of the antigen to the co-immobilized antibody. The calibration plot for cocaine was linear in the concentration range of lx 10 -1x10 M. 

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