Biosensors detection systems

Finally, the integration of biochemical or biosensor methods with conventional chromatographic analyses should not be overlooked. For example, the use of im-munoaffinity columns prior to chemiluminescence or the use of biosensor detection systems following the chromatographic step may provide useful solutions to speciflc analytical needs. 

There is increasing interest in the use of specific sensor or biosensor detection systems with the FIA technique (Galensa, 1998). Tsafack et al. (2000) described an electrochemiluminescence-based fibre optic biosensor for choline with flow-injection analysis and Su et al. (1998) reported a flow-injection determination of sulphite in wines and fruit juices using a bulk acoustic wave impedance sensor coupled to a membrane separation technique. Prodromidis et al. (1997) also coupled a biosensor with an FIA system for analysis of citric acid in juices, fruits and sports beverages and Okawa et al. (1998) reported a procedure for the simultaneous determination of ascorbic acid and glucose in soft drinks with an electrochemical filter/biosensor FIA system. 

The complexity of die flow injection manifold required by the three approaches was very similar. All of them necessitated electronic interfaces to control the propulsion and injection systems through the microcomputer in approaches I and II, and the injection and switching valves in manifold III. A passive electronic interface was also required in all three manifolds in order to acquire data fi om the biosensor/detection system. 

Biosensor Detection Systems Engineering Stable, High-Affinity Bioreceptors by Yeast Surface Display... 

Wang J., Krause R., Block K., Musameh M., Mulchandani A., Mulchandani P., Chen W., and Schoning M. J., Dual amperometric-potentiometric biosensor detection system for monitoring organophosphorus neurotoxins. Anal. Chim. Acta, 469, 197-203,... 

Fibre optic-based flow-through optical biosensors The dramatic advances in fibre optic development in die last decade have promoted construction of sensors where radiation, whether emitted, transmitted or reflected, is conducted fi-om the sample to the detection system. The wide variety of available optical waveguide types (solid rods, hollow cylinders, micro-planar geometries) has been used with varying success in sensor development. 

R.W. Min, V. Rajendran, N. Larsson, L. Gorton, J. Planas and B. Hahn-Hagerdal, Simultaneous monitoring of glucose and L-lactic acid during a fermentation process in an aqueous two-phase system by on-line FIA with microdialysis sampling and dual biosensor detection, Anal. Chim. Acta, 366(1-3) (1998) 127-135. 

The second reaction gives a colored product that can be detected in a spectrophotometer at 555 nm. The free-enzyme FIA system used an enzyme-reagent solution as described in a previous work (4). The immobilized AOD (0.1 mL of AOD with 4.5 mL of phosphate buffer, pH 7.0) integrating the biosensor-FIA system worked with phosphate buffer (pH 7.0), HRP (0.5 mg/mL), and reagent solution consisting of 0.875 g/L of phenol and 0.305 g/L of 4-aminophenazone was added. 

A biosensor utilizes a biological component to translate the concentration of a specific analyte of interest into a signal detectable by some chemical or physical means (7). Successful operation of a biosensor requires that the biological component and the signal it transduces be localized to and concentrated within a region in close proximity to the detection system. Immobilization of enzymes within a polymeric matrix ensures concentration and localization of the enzymic reaction, and creates a convective barrier, thus preventing dilution and convective removal of the product species before it is detected. Enzymes immobilized on or near the detection system are frequently used as the... 

Another sensor based on a fiber-optic-based spectroelectrochemical probe uses a DNA/ethidium bromide system to take advantage of the biological recognition processes [92]. The concept of immobilizing electrochemical reagents on the end of an optical fibre is a useful addition to the field of bioanalytical sensors. Before this development, optical and electrochemical detection of DNA were performed separately. Optical and electrochemical detection of DNA are suitable for a DNA detection system [93, 94] and these techniques will enable a production of a cheap DNA biosensor with a rapid and quantitative response. 

The detection system utilized in commercially available Biacore biosensors (Biacore, Sweden) is also based on SPR, an optical phenomenon that arises when... 

Bums A, Ow H, Wiesner U. Huorescent core-shell silica nanoparticles towards Lab on a Particle architectures for nanobiotechnology. Chem. Soc. Rev. 2006 35 1028-1042. Hindson BJ, Makarewicz AJ, Setlur US, Henderer BD, McBride MT, Dzenitis JM. APDS the autonomous pathogen detection system. Biosensors Bioelectron. 2005 20 1925-1931. 

The simple and inexpensive electrochemical detection systems are easier to miniaturize and included within the biosensor chip than their optical counterparts. They will thus lead to truly miniaturized systems in the near future. However, improvements in the optoelectronic technology will allow... 

Several implanted biosensors have been developed and evaluated in both animals and humans (see Chapter 4). Detection systems are based on enzymes, electrodes, or fluorescence. The most widely studied method is an electrochemical sensor that uses glucose oxidase. This sensor can be implanted intravenously or subcutaneously. Intravenous implantation in dogs for up to 3 months has demonstrated the feasibility of this approach. Alternatives to enzymes are being developed, including artificial glucose receptors. Less success has been achieved with subcutaneous implants. Implantation of a needle type of sensor into the subcutaneous tissue induces a host of inflammatory responses that alters the sensitivity of the device. Microdialysis with hoUow fibers or ultrafiltration with biologically inert material can decrease this problem. 

Biosensors based on a Clark oxygen electrode, coupled to tyrosinase immobilized by three different methods, were investigated for the determination of phenol in real matrices, such as water of various natural sources, industrial wastes and oil press. The feasibility study included direct use of the biosensors and in situ analysis. An integrated system, incorporating SPE, desorption, fractionation and biosensor detection, was validated for screening phenolic compounds in water. Two types of electrode were tested, solid graphite and CPE incorporating tyrosinase. Correct analyses were found for river water samples spiked with phenol (10 p.gL ), p-cresol (25 p.gL ) and catechol (1 A mul-... 

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