Biosensor immuno

Figure 1.26 Scheme of immuno-biosensor developed by Liu and Gooding, exploiting the size of proteins and the space that a protein takes up to block ion access to the redox probe. (Reproduced by permission of The Royal Society of Chemistry from [142].)... 

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. 

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. 

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. 

Example Optical techniques Biosensor/ Bioassays Immuno- Electroassay chemistry... 

Traynor, I.M. et al., Immuno biosensor detection of domoic acid as a screening test in bivalve molluscs comparison with liquid chromatography-based analysis, J AOAC Int 89, 868, 2006. 

Field-effect Transistors Enzyme FETs and immuno FETs (IMFETs) are based on principles similar to those valid in potentiometric membrane biosensors. The enzyme is immobihzed on top of the ion-selective membrane on the gate of the FET. For construction of ENFETs, usually double-gate FETs are used employing one gate as a reference system, covered only with a layer of the immobilization matrix, and allowing for the real-time compensation of pH modulations, temperature, and drift. Mostly, pH-sensitive FETs (ISFET)... 

Martin SP, Townsend RJ, Kuznetsova LA, Borthwick KJ, Hill M, Mcdonnell MB, Coakley WT (2005) Spore and micro-particle capture on an immuno-sensor surface in an ultrasound standing wave system. Biosensors Bioelectron 21 758-767... 

If a biochemical mechanism (mostly enzymatic catalysis, immuno-chemical reaction or complementary DNA hybridization) is used in the molecular recognition step, the sensor is called a biosensor. Systems of this type are dealt with in Chapter 28.3. 

Problems associated with inadequate lifetimes are best overcome with mass-produced miniaturized replacement sensors based on inexpensive materials. Minimizing replacement costs may well represent the future of biosensors. Installation of a new sensor to replace one that is worn-out can also circumvent surface fouling, interfering layers of proteins, and certain drift and poisoning problems. The integrated optical system lOS developed at the ICB Muenster and described in Section 28.3.3.2 has shown for the first time how to work with pre-calibrated low-cost immuno-chips with long storage capability. 

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