Optical fibers biosensor applications

Since the early 1980s, considerable research effort has been devoted to the development of fiber optic (FO) biosensors because their potential sensitivity, detection speed, and adaptability to a wide variety of assay conditions. The area of optical fibers biosensors is quite wide and numerous applications have been described in the literature, mainly via the evanescent wave detection [1,16—19]. A number of possibilities for FO sensing have been proposed and some of them have reached commercial development [1,16]. 

R.E. DESSY, L. BURGESS, L. ARNEY and J. PETERSEN "Fiber-optic- and polymer film-based enthalpimeters for biosensor applications" in "Chemical Sensor and Microinstrumentation", ACS Symposium series 403, 1989. 

Similar optical biosensors have been prepared for many other analytes. For example, a cholesterol optical biosensor has been devised based on fluorescence quenching of an oxygen-sensitive dye that is coupled to consumption of oxygen resulting from the enzyme-catalyzed oxidation of cholesterol by the enzyme cholesterol oxidase. Serum bilirubin has been detected using bilirubin oxidase, coimmobilized with a ruthenium dye, on an optical fiber.The bilirubin sensor was reported to exhibit a lower detection limit of iO Xmol/L, a linear range up to 30mmol/L, and a typical reproducibihty of 3% (CV), certainly adequate for clinical application. 

The enhanced chemiluminescense obtained with the horseradish peroxidase-H202-luminol (139) system was applied to the development of a CLD biosensor for p-iodophenol, coumaric acid (26), 2-naphthol and hydrogen peroxide. The enzyme was immobilized by microencapsulation in a sol-gel matrix. LOD for the phenolic compounds were 0.83 p,M, 15 nM and 48 nM, respectively. A remote version of the enhanced biosensor was designed by directly immobilizing the enzyme on the tip of an optical fiber. This model was used for H2O2 assay. LOD was 52.2 p,M, with RSD 4.7% (w = 4) °. A bioluminescent response was obtained for phenols with pA a > 7 in the presence of a recombinant Escherichia coli strain, DPD2540, containing a fabA luxCDABE fusion this behavior may have analytical applications. 

Based on the theories of geometric and wave optics, light propagates within optical fibers in the form of orthogonal modes. The light power distribution, in MM fibers, can be analyzed and characterized by using geometric and wave optics. In order to evaluate the MPD, within MM fibers, the wave equation, which is a second-order differential equation, has to be solved in cylindrical coordinate system. A summary of the MPD analysis is presented next, with an example on application to chemical and biosensors. 

In this chapter, a general introduction to fiber-optic sensors is presented, followed by sections on the principle of sensors design and sensors development and processing, as well as on sensors characterization and optimization. The technical feasibility and viability of fiber optics in chemical and biosensors applications have been demonstrated with a number of examples and a list of references on successfully reported research. Also, an overview on state-of-the-art research is presented, which is still under development and requires more work before the ultimate limits imposed by fiber optics science and technologies are reached. 

Fiber optic chemical sensors and biosensors offer important advantages for in situ monitoring applications because of the optical nature of the detection signal. Recent advances in nanotechnology leading to the development of optical fibers with submicron-sized dimensions have opened up new horizons for intracellular measurements. 

Fiber-Optic- and Polymer Film-Based Enthalpimeters for Biosensor Applications... 

Two novel enthalpimeters for biosensor applications are described. One of these employs a fiber optic interferometer, the other piezo/pyroelectric po1yviny1idene fluoride films. Applications to urease and catalase systems are descr ibed. 

Schaffar, B. P. H., B. A. A. Dremel, and R. D. Schmid. 1989. Ascorbic acid determination in fruit juices based on a fiber optic ascorbic acid biosensor and flow injection analysis. In Biosensors Applications in Medicine, Environmental Protection and Process Control, eds. R. D. Schmid, and F. Scheller, pp. 229-232. New York VCH Publishers. 

A large technological expansion has also occurred in the area of fiber optics. Improvements have been made in the optical quality and mechanical resistance of optical fibers, and they now have many applications in transducers. Optical fibers lend themselves to the construction of biosensors a suitable biological substance is attached to the tip of the fiber and produces an optical signal when it is in contact with the system under study [8]. Optical biosensors exploit a variety of radiation phenomena, for example, absorption, fluorescence, and... 

Schaffar B.P.H., Wolfbeis O.S., Chemically Mediated Fiber Optic Biosensors, chapter 8 in Biosensors Principles and Applications, L.J. Blum, P.R. Coulet (eds.), M. Dekker, New York, chapter 8, pp. 163-194 (1991). 

S. L. R. Barker, Y. Zhao, M. A. Marietta, and R. Kopelman, Cellular Applications of a Fiber-Optic Biosensor Based on a Dye-Labeled Guanylate Cyclase, And. Chem. 1999, 71, 2071 M. Kuratli and E. Pretsch, S02-Selective Optodes, AnaL Chem. 1994,66, 85. 

Aizawa presented an overview on the principles and applications of the electrochemical and optical biosensors [61]. The current development in the biocatalytic and bioaffinity bensensor and the applications of these sensors were given. The optical enzyme sensor for acetylcholine was based on use of an optical pH fiber with thin polyaniline film. 

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