|
|
|
|
|
Biosensor Technology
|
|
|
BIOSENSOR TECHNOLOGY The thesis here is done to develop an understanding of biosensors in general and then appreciate the construction of antibody sensors which are a boon to the medical industry to detect pathogens in the body much earlier than any known conventional pathology – lab test. This device can ultimately save lives because of the quick diagnosis that medical practitioners can provide to their patients. Moreover an antibody sensor can detect even traces of an antibody in a sample and thereby provide very accurate analytical data. A Brief Introduction: Biosensors were originally developed to meet the requirements of the medical industry. For example, doctors wanted to know the blood – sugar levels of their patients in the shortest possible time with sufficient accuracy to enable a wise diagnosis. Biosensors are basically measuring instruments that can detect the presence of certain biomolecules and measure the quantity of that substance with sufficient accuracy using a unique property of that substance in its interaction with some other base (reference) material. But now they are universally used to monitor bioprocesses in bioreactors- the most complex of which is the human body itself- the marvel of creation, the sceptre of divine power. Our aim is to study the fundamental theory of working of a general biosensor and then discover the flexibility and the accuracy of an Antibody Sensor. An antibody sensor is just a special biosensor that uses the unique properties of antibody – antigen reaction to its advantage, to detect antibodies. Now we shall consider the basic construction and working of a biosensor. What we need to keep in mind is that at ground zero we are going to use some unique property of the substance to be detected, when it reacts with a reference molecule [which could be part of the biosensor equipment]. This unique property can be a particular change in colour ( optical phenomenon ) during the course of the reaction, or a change in the sound during the reaction ( acoustic phenomenon ) , or change in electrode potential of a particular substrate or change in the pH of the reaction medium . The only necessity here is that the change being measured should be unique to that substance and also be of significance in the greater perspective – that the change is actually a measure of the presence of that particular molecule that we want to observe. Once the chemical or physical change [or a combination of both] has been picked up by the sensing part of the biosensor this is fed to a transducer. A transducer is the component of the biosensor that converts the observed chemical or physical change to an electrical signal which can in turn be inter converted between other electromagnetic fields. The output of the transducer is generally obtained as the mechanical deflection of a needle across a properly marked dial or as a digital display. Though different situations require different types of biosensors the basic principles underlying their construction and working is the same. A good biosensor is one that can endure the market – it should be produced economically, that is, using existing factory techniques. It should serve the purpose for which it was initially required. For example, if it were built for the purpose of research then it should be very accurate, with a reasonable compromise of cost. Theory Of The Detector Analyser (Biomaterial Properties): The detector does the work of biomolecular recognition. Biomolecular recognition provides the basis for bioreactor control processes in the biochemical industry. The detector is the core of the biosensor. It does the real analysis that can give us the required data. The detector is basically a setup that allows a reagent to react with the substrate in stoichiometric quantities and then by monitoring the change in concentration of the reagent or the substrate – produce a noticeable physical (optical, acoustic), or chemical (pH, electrode potential) change that can be picked up by the transducer to be converted to an appropriate electrical signal. Proteins by their virtue of their structural and chemical properties are the best candidates for detector (biomolecular recognition) molecules. It is because of the unique presence of an amino group and a carboxylic group in the same molecule and the varied chiralty that the alpha – carbon can exhibit that makes proteins so stereo specific in their reactions. There are some very special proteins called enzymes that are of special interest because of the factors listed below: They are one of those classes of organic compounds about which sufficient research has already been done and hence their chemistry is pretty well understood. Some are readily available. They are very specific in their reactions. They generally yield products that can be easily recognised and measured by already existent stoichiometric methods. Generally purified enzymes are used for the process of analysis (albeit mainly for the analysis of chromosomes). Purified doesn’t necessarily mean absence of all other proteins but just that the absence of proteins that could react in that particular situation under those conditions to mess up the analysis. Non reactive proteins could remain in the analyser matrix. Highly purified enzymes (with zero impurities) are used in the analysis of protein structure and modification, or for previously uncharted tests. The requisites of analytic enzymes are: Specificity - in reaction. Purity - absence of reactive proteins that may interact with the detection and analytical systems. Stability – capable of long term storage and stability even during reaction. Kinetic Properties – the sample compound should not contain some entity that inhibits enzyme action. pH – the enzyme pH should be optimum under the required conditions. Solubility – the enzyme should be such that adsorption or aggregation should not affect its activity. Cost Effectiveness. Once all these requisites are satisfied we have found the enzyme that will help us in our analysis. Now comes in the factor of transforming the chemical signals to electrical signals. We do this because among all fields we have understood very well, we have understood the electrical field the best. We have learnt to manipulate electric signals to meet our needs whenever required. Whenever enzymes are used as anylate molecules, they are first combined with electrodes to check for phenolic compounds, because phenols are enzyme inhibitors (this is why smokers are in a greater health risk because the carcinogens in tobacco smoke are mainly phenolic in nature and hence inhibit the activity of the enzymes in the smoker’s body). Antibodies are another class of proteins that have properties favourable for use in biosensors. They are not catalytic. They are very specific and bind only to a type specific compounds called antigens, that are specific to each antibody.
|
|
|
|
Still Can't Find What Your Looking For? Then Try a Essay Search!
|
