Optical Biosensors
The field of biosensors has emerged as a topic of great interest because of the great need in medical diagnostics and, more recently, the worldwide concern of the threat of chemical and bioterrorism. The constant health danger posed by new strands of microbial organisms and spread of infectious diseases is another concern requiring biosensing for detecting and identifying them rapidly. Optical biosensors utilize optical techniques to detect and identify chemical or biological species. They offer a number of advantages such as the ability for principally remote sensing with high selectivity and specificity and the ability to use unique biorecognition schemes. The topic of optical biosensors is comprehensively covered in this chapter.
The objectives of this chapter are many. First, it describes the basic optical principles and the various techniques utilized in biosensing, which can be useful as a text for students or non-experts in this field. Second, the detailed coverage of the various optical biosensors, reported ongoing activities, and a list of commercially available optical biosensors can serve as a valuable reference source for researchers. Finally, some examples of opportunities for future developments, provided at the end of the chapter, are intended to stimulate the interest of a new researcher or one interested in expanding an ongoing research and development program in this field.
The two important components of biosensing, discussed in this chapter, are (i) a biorecognition element to detect chemical or biological species and (ii) a transduction mechanism which converts the physical or chemical response of biorecognition into an optical signal. The various types of biorecognition elements are discussed. This is followed by a coverage of the various principles of optical transduction and optical geometries utilized for biosensing. An important aspect of biosensing is to immobilize the biorecognition element to increase its local concentration in the sensor probe. The various physical and chemical methods utilized for this purpose are described.
The subsequent sections describe various types of optical biosensors that have been reported, some of which are already in practice. Specifically, these are fiber-optic biosensors, planar waveguide biosensors, evanescent wave
Introduction to Biophotonics, by Paras N. Prasad.
ISBN: 0-471-28770-9 Copyright © 2003 John Wiley & Sons, Inc.
biosensors, interferometric biosensors, and surface plasmon resonance (abbreviated as SPR) biosensors.
Some novel sensing methods reported recently are described in Section 9.9. Next is a discussion of future development opportunities in Section 9.10. The chapter concludes with Section 9.12, which provides a list of commercial available biosensors.
For further reading, suggested general references are:
Wolfbeis (1991): Covers fiber-optics-based chemical and biosensors
Boisdé and Harmer (1996): Covers optical fibers and waveguide-based sensors
Ramsay (1998): Covers commercial biosensors
Mehrvar et al. (2000): Covers trends and advances in fiber-optic biosensors
Ligler and Rowe-Taitt (2002): Provides comprehensive, up-to-date coverage of optical biosensors
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