Optical fiber biosensors coupled fluorescence

An NIR biosensor coupled with an NIR fluorescent sandwich immunoassay has been developed. 109 The capture antibody was immobilized on the distal end of an optical fiber sensor. The probe was incubated in the corresponding antigen with consecutive incubation in an NIR-labeled sandwich antibody. The resulting NIR-labeled antibody sandwich was excited with the NIR beam of a laser diode, and a fluorescent signal that was directly proportional to the bound antigen was emitted. The sensitivity of the technique increased with increasing amounts of immobilized receptor. There are several factors involved in the preparation of the sandwich type biosensor. A schematic preparation of the sandwich optical fiber is shown in Figure 7.14. 

Localized Surface Plasmon Coupled Fluorescence Fiber-optic Biosensor... 

Hsieh B.-Y., Chang Y.-F., Ng M.-Y., Liu W.-C., Lin C.-H., Wu H.-T., and Chou C. (2007). Localized surface plasmon coupled fluorescence fiber-optic biosensor with gold nanoparticles. Anal. Chem. 79, 3487-3493. 

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. 

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