Biochemical Sensors Biosensors

Biosensors are in general small devices based on a direct spatial coupling between a biologically 

The first indicating step is specific complex formation between the immobilized biologically 

Depending upon the mechanism of biochemical interaction between the receptor and the analyte, two basic types of biosensors can be distinguished biocatalytic (metabolic) sensors, and bio-affinity sensors (Table 18). 

Among the analytes detectable with biosensors are carbohydrates, organic acids, alcohols, phenols. amines, heterocyclic compounds, proteins, enzymes, cofactors, inorganic ions, hormones, vitamins. peptides, drugs, xenobiotics. microorganisms, gases, and pesticides. Analyte concentrations 

1) First Generation. The receptor is entrapped between or bound to membranes, and the combination is fixed on the surface of an appropriate transducer or known chemical sensor.  

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Narayanaswamy R (1991) Current developments in optical biochemical sensors. Biosensors and Bioelectronics 6 467- 75. 

Major Applications pH Sensors, optical chemical sensors, biochemical sensors, biosensors," fluorescent pH detector system, measuring fluorescence lifetime in cells, determining concentration of a laminar sample stream, fluorescent reporter beads for fluid analysis, measuring ch ical analytes, intracellular pH in human sperms, " multidrug resistance," recording intramitochon-drial pH, fluorescent probes ... 

Although the construction of sensors for external physical stimuli, such as light, heat or pressure, is relatively simple, it becomes more complicated when the target stimuli come from atoms or molecules. These types of sensors are often referred to as chemical sensors or chemosensors and biochemical sensors or biosensors (see below in Sects. 1.2 and 1.3). For the latter types, a sensing material should be used that can respond to the presence of the target analyte. This response may or may not be obviously true with vague information. Hence, chemo- and biosensors should be... 

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. 

Tang, F. Wang, X., Xu, C., FAIMS biochemical sensor based on MEMS technology, in New Perspectives in Biosensors Technology and Applications, Serra, A.P. (Ed.) ISBN 978-953-307-448-1, InTech, Shanghi, China, 2011, pp. 1-32. 

This volume presents a cross section of recent advances in the development of novel chemical and biochemical sensors for on-line monitoring and control applications in the environmental, clinical, and bioprocess areas. These chapters illustrate how many of the key challenges for continuous monitoring are being addressed. The methods discussed include optical techniques ranging from near-infrared spectroscopy to lifetime-based phase fluorometry biosensors ranging from optical immu-nosensors to enzyme-electrodes as well as electrochemical, acoustic, and plasmon resonance techniques. 

The benefits of modifying EIS structures with LbL films to achieve biosensors with improved performance was also reported by Abouzar et al., who observed an amplification of the signal response upon alternating layers of polyelectrolytes and enzymes as gate membranes on the p-Si-Si02 EIS structure [99]. A new variant of EIS sensors has been produced, which comprised an array of individually addressable nanoplate field-effect capacitive biochemical sensors with an SOI (silicon-on-insulator) stmcture to determine pH and detect penicillin. It also allows for the label-free electrical monitoring of formation of polyelectrolyte multilayers and DNA (deoxyribonucleic acid)-hybridization event [100]. 

Spichiger-Keller, U.E. Chemical and Biochemical Sensors. In Spichiger-Keller U.E. (ed.) Chemical Sensors and Biosensors for Medical and Biological Applications, pp. 33-81. Wiley-VCH Verlag GmbH, German (1998). doi 10.1002/9783527612284.ch2... 

Pilloton R, Mela J, Marradini L (1999) Screen printed electrochemical biosensors on ceramic and polymeric substrates. Advances in science and technology solid state chemical and biochemical sensors, vol. 26, pp. 501-507. 

Entrapment of biochemically reactive molecules into conductive polymer substrates is being used to develop electrochemical biosensors (212). This has proven especially useful for the incorporation of enzymes that retain their specific chemical reactivity. Electropolymerization of pyrrole in an aqueous solution containing glucose oxidase (GO) leads to a polypyrrole in which the GO enzyme is co-deposited with the polymer. These polymer-entrapped GO electrodes have been used as glucose sensors. A direct relationship is seen between the electrode response and the glucose concentration in the solution which was analyzed with a typical measurement taking between 20 to 40 s. 

A strain of yeast and a strain of bacterium were co-immobilized to fabricate a biochemical oxygen demand (BOD) sensor based on sol-gel derived composite materials97. This novel type of biosensor was developed for water monitoring and was used to determine the BOD values of OECD synthetic wastewater, domestic wastewater, and lake waters. The microorganisms Trichosporon cutaneum and Bacillus subtilis were coimmobilized in the sol-gel composite material, which was composed of silica and the grafting copolymer of poly (vinyl alcohol) and 4-vinylpyridine (PVA-g-P(4-VP)). 

The flow-through sensors described in this Section comply essentially with the definition of biosensor. This word, like every term used to designate devices of scientific and popular note, has been the object of a number of definitions of both generic and specific scope. In a broad sense, a biosensor is any instrument or technique that measures biomolecules. In stricter terms, Rechnitz defines a biosensor as "a device that incorporates a biochemical or biological component as a molecular recognition element and yields an analytical signal in response to biomolecules" [10]. In between these two... 

Biochemical oxygen demand (BOD) is one of the most widely determined parameters in managing organic pollution. The conventional BOD test includes a 5-day incubation period, so a more expeditious and reproducible method for assessment of this parameter is required. Trichosporon cutaneum, a microorganism formerly used in waste water treatment, has also been employed to construct a BOD biosensor. The dynamic system where the sensor was implemented consisted of a 0.1 M phosphate buffer at pH 7 saturated with dissolved oxygen which was transferred to a flow-cell at a rate of 1 mL/min. When the current reached a steady-state value, a sample was injected into the flow-cell at 0.2 mL/min. The steady-state current was found to be dependent on the BOD of the sample solution. After the sample was flushed from the flow-cell, the current of the microbial sensor gradually returned to its initial level. The response time of microbial sensors depends on the nature of the sample solution concerned. A linear relationship was foimd between the current difference (i.e. that between the initial and final steady-state currents) and the 5-day BOD assay of the standard solution up to 60 mg/L. The minimum measurable BOD was 3 mg/L. The current was reproducible within 6% of the relative error when a BOD of 40 mg/L was used over 10 experiments [128]. 

Ruzicka ei al. [57,58] developed some peculiar reflectance flow-through biosensors based on a sensing microzone accommodating an enzyme and an acid-base indicator (both in immobilized form) where spacial and temporal resolution of the biochemical and chemical reaction or the reversible separation of hydrogen ions was therefore impossible. The pH sensors developed by these authors (see Section 3.5.1.1) can be regarded as precedents for these reflectance sensors. The sensing approach used relies on... 

For all these reasons, a microbial BOD-sensor needs to be calibrated before it can be used as a biochemical activity test. Only after a foregoing calibration procedure does a BOD-sensor finally reveal results which are both reliable and comparable to the conventional BOD5 method. Some consideration concerning the calibration of biosensors are given in Sect. 3.2.1.6. 

Liu J, Bjornsson L, Mattiasson B (2000) Immobilised activated sludge based biosensor for biochemical oxygen demand measurement. Biosens Bioelectron 14 883-893 Sakai Y, Abe Y, Takahashi F (1995) BOD sensor using magnetic activated sludge. J Ferment Bioeng 80 300-303... 

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