biosensor


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Biosensor

An integrated device consisting of a biological recognition element and a transducer capable of detecting the biological reaction and converting it into a signal which can be processed. Ideally, the sensor should be self-contained, so that it is not necessary to add reagents to the sample matrix to obtain the desired response. There are a number of analytes (the target substances to be detected) which are measured in biological media: pH, partial pressure of carbon dioxide (pCO2), partial pressure of oxygen (pO2), and the ionic concentrations of sodium, potassium, calcium, and chloride. However, these sensors do not use biological recognition elements, and are considered chemical sensors. Normally, the biological recognition element is a protein or protein complex which is able to recognize a particular analyte in the presence of many other components in a complex biological matrix. This definition has since been expanded to include oligonucleotides. The recognition process involves a chemical or biological reaction, and the transducer must be capable of detecting not only the reaction but also its extent. An ideal sensor should yield a selective, rapid, and reliable response to the analyte, and the signal generated by the sensor should be proportional to the analyte concentration.

Biosensors are typically classified by the type of recognition element or transduction element employed. A sensor might be described as a catalytic biosensor if its recognition element comprised an enzyme or series of enzymes, a living tissue slice (vegetal or animal), or whole cells derived from microorganisms such as bacteria, fungi, or yeast. The sensor might be described as a bioaffinity sensor if the basis of its operation were a biospecific complex formation. Accordingly, the reaction of an antibody with an antigen or hapten, or the reaction of an agonist or antagonist with a receptor, could be employed. In the former case, the sensor might be called an immunosensor.

Since enzyme-based sensors measure the rate of the enzyme-catalyzed reaction as the basis for their response, any physical measurement which yields a quantity related to this rate can be used for detection. The enzyme may be immobilized on the end of an optical fiber, and the spectroscopic properties (absorbance, fluorescence, chemiluminescence) related to the disappearance of the reactants or appearance of products of the reaction can be measured. Since biochemical reactions can be either endothermic (absorbing heat) or exothermic (giving off heat), the rate of the reaction can be measured by microcalorimetry. Miniaturized thermistor-based calorimeters, called enzyme thermistors, have been developed and widely applied, especially for bioprocess monitoring.

In the case of affinity biosensors, as is true of catalytic biosensors, many physical techniques can be used to detect affinity binding: microcalorimetry (thermometric enzyme-linked immunosorbent assay, or TELISA), fluorescence energy transfer, fluorescence polarization, or bioluminescence.

The quality of the results obtained from sensors based on biological recognition elements depends most heavily on their ability to react rapidly, selectively, and with high affinity. Antibodies and receptors frequently react with such high affinity that the analyte does not easily become unbound. To reuse the sensor requires a time-consuming regeneration step. Nonetheless, if this step can be automated, semicontinuous monitoring may be possible.

biosensor

[¦bī·ō¦sen·sər]
(analytical chemistry)
An analytical device that converts the concentration of an analyte in an appropriate sample into an electrical signal by means of a biologically derived sensing element intimately connected to, or integrated into, a transducer.

biosensor

A device that detects a person's body movement, temperature, pulse rate and other physical characteristics, which it converts into electronic signals. See lab on a chip, smart clothes, biowearable and data glove.
References in periodicals archive ?
5, 2015 /PRNewswire/ -- The biosensors market is proving highly attractive as it exhibits continuous growth in applications, penetration into newer sectors, and development of devices resulting in higher revenue year after year.
Results of the research have been published in Biosensors and Bioelectronics, vol.
Biosensors have been recently used in medical, biological and industrial aspects to increase the speed of diagnosis.
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Axela offers a biosensor system based on diffractive optics technology.
What Theron needs now is capital to get it off the ground A new biosensor company will spin off from Theron when the products are launched, says Gray, and the company could employ as many as 300 people in eight to 10 years.
Under the terms of the agreement, the license gives Innovative Biosensors exclusive rights to use this technology in the fields of food testing, human and animal clinical diagnostics, and sales to the life science research market.
5] have recently described a recombinant cell based biosensor containing a peptidoglycan-associated lipoprotein (PAL) fused to an antibody fragment (scFv) specific to the herbicide and environmental pollutant atrazine.
Georgia Tech researchers and colleagues have been developing and testing the biosensor in their lab for about four years.
The electrode in the biosensor detects oxygen levels and sends the information to a computer that displays the data in graph form.
A biosensor is an analytical device that uses a biodetector (enzymes, antibodies, nucleic acids, microorganisms, or tissues) to perceive a target analyte directly without the need for complex specimen processing [ILLUSTRATION FOR FIGURE 2 OMITTED].