Enzyme-based biosensors, development

Table 8.1 Examples of enzyme-based biosensors developed in the author s lab for evaluation of food quality, safety, and process control...

S. Jawaheer, S.F. White, S.D.D.V. Rughooputh and D.C. Cullen, Development of a common biosensor format for an enzyme based biosensor array to monitor fruit quality, Biosens. Bioelectron., 18(12) (2003) 1429-1437. 

In recent years the electrochemistry of the enzyme membrane has been a subject of great interest due to its significance in both theories and practical applications to biosensors (i-5). Since the enzyme electrode was first proposed and prepared by Clark et al. (6) and Updike et al. (7), enzyme-based biosensors have become a widely interested research field. Research efforts have been directed toward improved designs of the electrode and the necessary membrane materials required for the proper operation of sensors. Different methods have been developed for immobilizing the enzyme on the electrode surface, such as covalent and adsorptive couplings (8-12) of the enzymes to the electrode surface, entrapment of the enzymes in the carbon paste mixture (13 etc. The entrapment of the enzyme into a conducting polymer has become an attractive method (14-22) because of the conducting nature of the polymer matrix and of the easy preparation procedure of the enzyme electrode. The entrapment of enzymes in the polypyrrole film provides a simple way of enzyme immobilization for the construction of a biosensor. It is known that the PPy-... 

Pritchard et al. [131] describe the development of a single thiocholine enzyme-based biosensor. This biosensor is a sonochemically fabricated enzyme microelectrode array in order to impart stir-independent (convection) responses that are characteristic of microelectrodes. Microelectrode arrays with up to 2 x 10 microelectrode elements may be fabricated via the sonochemical ablation of noncondnc-tive polymer films [132,133], which coat and thereby insnlate nnderlying condnctive snrfaces [134]. Paraoxon is determined down to concentrations of 1 x 10 M via the nse of sonochemically fabricated acetylcholine/polyaniline microelectrode array-based sensors. These sensors were fabricated via the electropolymerization of thin... 

An approach which is now becoming of more importance in the development of enzyme-based biosensors is that of immobilisation of the active protein in a polymer matrix. We have now carried out a preliminary investigation into the incorporation of anti-HSA into an electrochemically-generated conducting polypyrrole film. Conducting polymers such as polypyrrole (I)... 

Enzyme immobilization is a well developed area of chemistry and numerous methods are available (18). We have prepared a variety of enzyme based biosensors using the following immobilization procedures 1) entrapment in crosslinked polyacrylamide (J7), 2) glutaraldehyde... 

Me Ardle, F.A., and K.G. Persaud. 1993. Development of an enzyme-based biosensor for atrazine detection. Analyst 118 419. 

Enzyme-based biosensors (1), and NIR spectroscopy (7,10) are currently being developed as continuous monitors for bioreactors. Enzyme-based biosensors are... 

The development of antibody-based biosensors presents more difficulties than enzyme-based biosensors as the antigen-antibody interactions are not readily reversible because of the high values of the affinity constants. Another limitation is that the physicochemical changes resulting from the immunochemical reaction are often insufficient to provide detection limits comparable with those of conventional analysis. As a consequence, indirect systems have been developed that rely on the use of enzyme-or fluorescent-tagged reagents. Both competitive and sandwich formats are used. Evanescent wave-induced fluorescence is frequently chosen to avoid possible interferences from the bulk media. For... 

This chapter will illustrate recent developments on surface characterisation of DNA and enzyme-based biosensors to complement information obtained by electrochemical and impedance techniques. 

CAD-Kit. The authors have developed and fielded an enzyme-based biosensor kit that detects nerve, blood and blister agents, and TICs (toxic industrial chemicals)/TIMs (toxic industrial materials) on surfaces (22,23). The penlike sensors of the Chemical Agent Detection Kit (CAD-Kit) consist of a spongelike polyurethane tip that contains immobilized enzymes. These enzymes are used to detect several different chemical compovmds. 

Enzyme-based biosensors have been developed both with potentiometric as well as amper-ometric transducers. Different potentiometric transducers have been used including the glass electrode for the measurement of pH or monovalent ions, specific electrodes sensitive to anions or cations, and gas electrodes such as PCO2 0 PNH3 electrodes. If an amperomet-ric electrode is used as the transducer of a biosensor, a consumption of reaction products is involved this is the major difference from a potentiometric electrode. Different types of electrodes can be used in amperometric biosensor sueh as oxygen sensor, gold, platinum, or graphite electrodes. 

Ispas, C.R., Crivat, G., Andreescu, S., 2012. Review recent developments in enzyme-based biosensors for biomedical analysis. Analytical Letters 45, 168-186. 

Enzyme-based biosensors have been used also for the detection of phenolic estrogens. The detection principle was based on the ability of tyrosinase to catalyze the oxidation of phenolic estrogens to o-diphenol and o-quinone. Using this principle tyrosinase-carbon paste electrodes have been used for the detection of phenol, catechol, bisphenol A, genistein, quercetin, nonylphenol, and diethylstilbestrol with detection levels in the micromolar range.Optical and amperometric biosensors based on estrogen receptors have also been developed. 

Numerous biosensors based on enzymes have been developed due to the success of the enzymatic biosensor for glucose. Research on enzyme-based biosensors... 

Enzyme sensors are based primarily on the immobilization of an enzyme onto an electrode, either a metallic electrode used in amperometry (e.g., detection of the enzyme-catalyzed oxidation of glucose) or an ISE employed in potentiometry (e.g., detection of the enzyme-catalyzed liberation of hydronium or ammonium ions). The first potentiometric enzyme electrode, which appeared in 1969 due to Guilbault and Montalvo [140], was a probe for urea with immobilized urease on a glass electrode. Hill and co-workers [141] described in 1986 the second-generation biosensor using ferrocene as a mediator. This device was later marketed as the glucose pen . The development of enzyme-based sensors for the detection of glucose in blood represents a major area of biosensor research. 

Particularly attractive for numerous bioanalytical applications are colloidal metal (e.g., gold) and semiconductor quantum dot nanoparticles. The conductivity and catalytic properties of such systems have been employed for developing electrochemical gas sensors, electrochemical sensors based on molecular- or polymer-functionalized nanoparticle sensing interfaces, and for the construction of different biosensors including enzyme-based electrodes, immunosensors, and DNA sensors. Advances in the application of molecular and biomolecular functionalized metal, semiconductor, and magnetic particles for electroanalytical and bio-electroanalytical applications have been reviewed by Katz et al. [142]. 

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