Biosensor/biosensing optical

Electrochemical devices have proven very useful for sequence-specific biosensing of DNA. Electrochemical detection of DNA hybridization usually involves monitoring a current response under controlled potential conditions. The hybridization event is commonly detected via the increased current signal of a redox indicator (that recognizes the DNA duplex) or from other hybridization-induced changes in electrochemical parameters (e.g., conductivity or capacitance). Modern electrical DNA hybridization biosensors and bioassays offer remarkable sensitivity, compatibility with modern microfabrication technologies, inherent miniaturization, low cost (disposability), minimal power requirements, and independence of sample turbidity or optical pathway. Such devices are thus extremely attractive for obtaining the sequence-specific information in a simpler, faster, and cheaper manner, compared to traditional hybridization assays. 

Optical biosensors can be defined as sensor devices which make use of optical principles for the transduction of a biochemical interaction into a suitable output signal. The biomolecular interaction on the sensor surface modulates the light characteristics of the transducer (i.e., intensity, phase, polarization, etc.), and the biosensing event can be detected by the change in diverse optical properties such as absorption, fiuorescence, luminescence or refractive index, among others. 

Optical biosensors have had, and still are having, an increasing impact on analytical technology for the detection of biological and chemical species. Optical biosensing technology can be an alternative and/or a complement to conventional analytical techniques as it avoids expensive, complex and time-consuming detection procedures. For this reason it has been the subject of active research for many years [1-6]. 

The latest developments on optical biosensors have been presented at specific conferences [100]. There is still a lot of ground to cover in the optical biosensing field, but this is a very active area of research and new and exciting developments will be achieved in the near future. 

Abdulhalim I, Zourob M, Lakhtakia A (2007) Overview of optical biosensing techniques. In Marks RS, Cullen DC, Karube I, Lowe CR, Weetaii HH (eds) Handbook of biosensors and biochips. Wiley, New York... 

In this chapter, an overview on fiber-optic chemical and biosensors is presented focusing on transducers and transduction mechanisms, sensor design, sensor development and processing, and sensor characterization and optimization. A few examples are presented on chemical vapor detection and biosensing applications. At the end of the chapter, the theory and application of the newly developed detection technique, which is called the SIM technique, is presented. 

Of comparable general importance is the bacterial luciferase system [226-228], which opens up the opportunity to combine any NAD(P) " -dependent enzyme-catalyzed reaction with a luminometric measurement. Even the chemiluminescent luminol reaction can be used for biosensing, because it can be coupled to any oxidase reaction that produces HjOj [225, 229]. The logical further development of these systems towards real optical biosensors has recently been reported by Blum et al. [230], who immobilized the light-producing systems onto the tip of optical fibers and thus obtained fiber-optic luminescence probes. 

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