Lecture (6 part-1) Biosensor

Biotechnology&Genetic Engineering Lecture (6 part-1) Assi. Prof. Rajaa Al-Anbagi

Biosensor-part- 1

INTRODUCTION

The history of biosensors started in the year 1962 with the development of enzyme electrodes by the scientist Leland C. Clark. Since then, research communities from various fields such as Physics, Chemistry, and Material Science have come together to develop for applications in the fields of medicine, agriculture, biotechnology. Various definitions and terminologies are used depending on the field of application.

A biosensor is a device for the detection of an analytic that combines a biological component with a physicochemical detector component . Another meaning biosensor is composed of two elements: a biological recognition unit able to interact specifically with a target, and a transducer able to convert a change in property of the solution or surface, due to complex formation, into a recordable or an electrical signal . The usual aim of using a biosensor is to produce a signal which is related to a single analyte or a related group of analytes. The name “biosensor” signifies that the device is a combination of two parts: (i) a bio-element, and (ii) a sensor-element The biological sensing elements used in biosensors are typically enzymes or binding proteins, such as antibodies, nucleic acids, bacteria and single cell organisms and even whole tissues or higher organisms. The choice of the biosensing element is decided by the substrate of interest (target analyte). The physico-chemical transducers may take many forms depending upon the parameters being measured; electrochemical, optical, mass, and thermal changes are the most common. If the selectivity is mainly decided at the biosensing element, the transducer often determines the sensitivity of a biosensor (See Fig .1). Biosensors offer a number of traditional methods, such as high performance liquid chromatography and gas chromatography, which require high maintenance costs, expert operators, and long analysis times, making them less practical for food process monitoring.

The parameter being measure optical biosensors ,many it based on the phenomenon of surface plasmon resonance are evanescent wave techniques The most widespread example of a commercial biosensor is the blood glucose biosensor, which uses the enzyme glucose oxidase to break blood glucose down As a consequence of the direct physical combination between the recognition and transducer elements, the interaction with the target is detected as it takes place. Biosensors therefore differ from conventional bioassays by the fact that auxiliary procedures (addition of reagents, separation steps) are not required . Biosensors and bioassays making them highly attractive for biotechnological applications .Another example the specificity of enzyme is the basis of biosensors (Fig .2) .

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