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18-02-2010, 01:12 PM
BIOSENSOR.ppt (Size: 1.21 MB / Downloads: 761)
Â¢ A biosensor is a device for the detection of an analytic that combines a biological component with a physicochemical detector component. Many optical biosensors 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
Biosensor consist of
Â¢ 1.the sensitive biological element
Â¢ 2.the transducer or detector element
Â¢ 3.signal processors
Â¢ Tiny and compactable
Â¢ Linear response
Â¢ Small, cheap
Â¢ Easy use
Â¢ Highly specific
a â€œ analyte
c - immobilized biological molecule
d -biospecific immobilization surface
e - chemical signal
g - amplification and control unit interferent
h - output of measured analyte
Response time is longer
After use it require more time
Cells contains many enzymes
1.Medicine and health
1. Potentiometric biosensors
2. Amperometric biosensors
3. Optimal biosensors
4. Calorimetric biosensors
5. Acoustic wave biosensors
Â¢ Use iron selective electrodes
Â¢ Electrodes used are
-solid state electrode
-ph meter glass electrode
Â¢ Gas sensing electrode detect and measure the amount of gas produced
Â¢ It measures the change in temperature
Â¢ It can be used for turbid and strongly colored solutions
Â¢ Eg-glucose oxidase for determination of glucose
Â¢ Production of current when potential applied between electrodes
Â¢ These are the first generation biosensors
Â¢ Used to measure redox reactions
Â¢ Measure both catalytic and affinity reactions
Â¢ They measure change in fluorescence
ACOUSTIC WAVE BIOSENSORS
Â¢ These are also called piezo electric devices
Â¢ There Surface is coated with antibodies which bind to the complementary antigen present in the sample solution
There are number of areas where the unique capabilities of biosensors might be exploted to meet the requirement of environmental monitering.advances in such areas such as toxity,bioavailability and multipollutant screening, could when the potential market and allow these techniques to be more competetive.miniatarizaion,reversability and continuous operation may allow biosensor techniques to be incorporated as detectors in chromatographic systems
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25-04-2010, 12:01 PM
biosensors.ppt (Size: 5.11 MB / Downloads: 271)
What is a Biosensor
A biosensor is a self-contained integrated device thai is capable of providing specific quantitative or semi-quantitative analytical information using a biological recognition element which is in direct spatial contact with a transduction element (IUPAC, 1996)
"Biosensor" - Any device that uses specific biochemical reactions to detect chemical compounds in biological samples.
A sensor that integrates a biological element with a physiochemical transducer to produce an electronic signal proportional to a single analyte which is then conveyed to a detector.
History of Biosensors
â€ 1916 First report on immobilization of proteins : adsorption of invertase on activated charcoal
â€ 1922 First glass pH electrode
â€ 1956 Clark published his definitive paper on the oxygen
First description of a biosensor: an amperometric e electrodre for glucose (Clark)
Guilbault and M ontalvo - First potentiometric biosensor:urease immobilized on an ammonia electrode to detect urea
Bergveld - ion selective Field Effect Transistor (ISFET)
cribed a fibre-optic sensor with immobilised ioxide or oxygen.
â€ 1975 First commercial biosensor ( Yellow springs Instruments glucose biosensor)
â€ 1975 First microbe based biosensor, First immunosensor
â€ 1976 First bedside artificial pancreas (Miles)
â€ 1980 First fibre optic pH sensor for in vivo blood gases
â€ 1982 First fibre optic-based biosensor for glucose
â€ 1983 First surface plasmon resonance (SPR)
â€ 1984 First mediated amperometric biosensor:
ferrocene used with glucose oxidase for glucose
Blood-glucose biosensor launched by
1990 SPR based biosensor by Pharmacia BIACore
1992 Hand held blood biosensor by i-STAT
1996 Launching of Glucocard
1998 Blood glucose biosenso r launch by LifeScan
1998 Roche Diagnostics by Merger of Roche and
Quantom dots, nanoparicles, nanowire,
Basic Characteristics of a Biosensor
Value of the electrode response per
3. SELECTIVITY Chemicals Interference must be
obtaining the correct result.
Time necessary for having 95%
1. The Analyte (What do you want to detect)
Molecule - Protein, toxin, peptide, vitamin, sugar, metal ion
2. Sample handling (How to deliver the analyte to the sensitive region)
(Micro) fluidics - Concentration increase/decrease), Filtration/selection
3. Detection/Recognition (How do you specifically recognize the analyte)
Typical Sensing Techniques for Biosensors Â¢/ Fluorescence Â¢/ DNA Microarray
Â¢ SPR Surface plasmon resonance
Â¢ Impedance spectroscopy
Â¢ SPM (Scanning probe microscopy, AFM, STM)
Â¢ QCM (Quartz crystal microbalance)
Â¢ SERS (Surface Enhanced Raman Spectroscopy)
Types of Biosensors
1. Calorimetric Biosensor
2. Potentiometric Biosensor
3. Amperometric Biosensor
4. Optical Biosensor
5. Piezo-electric Biosensor
ct the specific angle at which electron waves are d to laser light or crystals, such as quartz, which vibrate under the influence of an electric field.
Â¢ For applied current: Movement of e- in redox reactions detected when a potential is applied between two electrodes.
â€ For voltage: Change in distribution of charge is detected using ion-selective electrodes, such as pH-meters.
Â¢ Colorimetric for color Measure change in light adsorption
Â¢ Photometric for light intensity
Photon output for a luminescent or fluorescent process can be detected with photomultiplier tubes or photodiode systems.
If the enzyme catalyzed reaction is exothermic, two thermistors may be used to
the analyte concentration.
Electrochemical DNA Biosensor
Ã‚Â¦ Steps involved in electrochemical DNA hybridization biosensors:
Ã‚Â¦ Formation of the DNA recognition layer
Ã‚Â¦ Actual hybridization event
Ã‚Â¦ Transformation of the hybridization event into an electrical signal
Motivated by the application to clinical diagnosis and genome mutation detection
Types DNA Biosensors
Biosensors on the Nanoscale
Molecular sheaths around the nanotube are developed that respond to a particular chemical and modulate the nanotube's optical properties.
In a nanoelectrode react with low-concentration lect). Doctors can use to diagnose diseases at earlier
Nanosphere lithography (NSL) derived triangular Ag nanoparticles are used to detect streptavidin down to one picomolar concentrations.
The School of Biomedical Engineering has developed an anti- body based
piezoelectric nanobiosenso r to be used for anthrax,HIV hepatitis detection.
Application of Biosensor
Study of biomolecules and their interaction
Medical diagnosis (both clinical and laboratory use)
Environmental field monitoring
Industrial Process Control
Detection systems for biological warfare agents
Manufacturing of pharmaceuticals and replacement organs
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07-01-2011, 12:58 PM
Plz send me the report of biosensors immediately
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28-02-2011, 05:53 PM
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but i needed a pdf format report rather than a ppt....
plz c if u can help...
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06-09-2011, 01:04 AM
Great need of Full report regarding biosensors. [/color][/size][/font]
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06-09-2011, 09:29 AM
To get more information about the topic "biosensors " please refer the link below
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06-09-2011, 09:33 AM
thank you for your report. I learned more for you.
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09-02-2012, 02:32 PM
even detailed expalnation abt bio sensor..
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18-06-2012, 05:38 PM
biosensors.docx (Size: 54.58 KB / Downloads: 24)
A biosensor is an analytical device which converts a biological response into an electrical signal (Figure 6.1). The term 'biosensor' is often used to cover sensor devices used in order to determine the concentration of substances and other parameters of biological interest even where they do not utilise a biological system directly. This very broad definition is used by some scientific journals (e.g. Biosensors, Elsevier Applied Science) but will not be applied to the coverage here. The emphasis of this Chapter concerns enzymes as the biologically responsive material, but it should be recognised that other biological systems may be utilised by biosensors, for example, whole cell metabolism, ligand binding and the antibody-antigen reaction. Biosensors represent a rapidly expanding field, at the present time, with an estimated 60% annual growth rate; the major impetus coming from the health-care industry (e.g. 6% of the western world are diabetic and would benefit from the availability of a rapid, accurate and simple biosensor for glucose) but with some pressure from other areas, such as food quality appraisal and environmental monitoring. The estimated world analytical market is about �12,000,000,000 year-1 of which 30% is in the health care area. There is clearly a vast market expansion potential as less than 0.1% of this market is currently using biosensors. Research and development in this field is wide and multidisciplinary, spanning biochemistry, bioreactor science, physical chemistry, electrochemistry, electronics and software engineering. Most of this current endeavour concerns potentiometric and amperometric biosensors and colorimetric paper enzyme strips. However, all the main transducer types are likely to be thoroughly examined, for use in biosensors, over the next few years.
A successful biosensor must possess at least some of the following beneficial features:
1. The biocatalyst must be highly specific for the purpose of the analyses, be stable under normal storage conditions and, except in the case of colorimetric enzyme strips and dipsticks (see later), show good stability over a large number of assays (i.e. much greater than 100).
2. The reaction should be as independent of such physical parameters as stirring, pH and temperature as is manageable. This would allow the analysis of samples with minimal pre-treatment. If the reaction involves cofactors or coenzymes these should, preferably, also be co-immobilised with the enzyme (see Chapter 8).
3. The response should be accurate, precise, reproducible and linear over the useful analytical range, without dilution or concentration. It should also be free from electrical noise.
4. If the biosensor is to be used for invasive monitoring in clinical situations, the probe must be tiny and biocompatible, having no toxic or antigenic effects. If it is to be used in fermenters it should be sterilisable. This is preferably performed by autoclaving but no biosensor enzymes can presently withstand such drastic wet-heat treatment. In either case, the biosensor should not be prone to fouling or proteolysis.
5. The complete biosensor should be cheap, small, portable and capable of being used by semi-skilled operators.
6. There should be a market for the biosensor. There is clearly little purpose developing a biosensor if other factors (e.g. government subsidies, the continued employment of skilled analysts, or poor customer perception) encourage the use of traditional methods and discourage the decentralisation of laboratory testing.
The biological response of the biosensor is determined by the biocatalytic membrane which accomplishes the conversion of reactant to product. Immobilised enzymes possess a number of advantageous features which makes them particularly applicable for use in such systems. They may be re-used, which ensures that the same catalytic activity is present for a series of analyses. This is an important factor in securing reproducible results and avoids the pitfalls associated with the replicate pipetting of free enzyme otherwise necessary in analytical protocols. Many enzymes are intrinsically stabilised by the immobilisation process (see Chapter 3), but even where this does not occur there is usually considerable apparent stabilisation. It is normal to use an excess of the enzyme within the immobilised sensor system. This gives a catalytic redundancy (i.e. << 1) which is sufficient to ensure an increase in the apparent stabilisation of the immobilised enzyme (see, for example, Figures 3.11, 3.19 and 5.8). Even where there is some inactivation of the immobilised enzyme over a period of time, this inactivation is usually steady and predictable. Any activity decay is easily incorporated into an analytical scheme by regularly interpolating standards between the analyses of unknown samples. For these reasons, many such immobilised enzyme systems are re-usable up to 10,000 times over a period of several months. Clearly, this results in a considerable saving in terms of the enzymes' cost relative to the analytical usage of free soluble enzymes.
When the reaction, occurring at the immobilised enzyme membrane of a biosensor, is limited by the rate of external diffusion, the reaction process will possess a number of valuable analytical assets. In particular, it will obey the relationship shown in equation 3.27. It follows that the biocatalyst gives a proportional change in reaction rate in response to the reactant (substrate) concentration over a substantial linear range, several times the intrinsic Km (see Figure 3.12 line e). This is very useful as analyte concentrations are often approximately equal to the Kms of their appropriate enzymes which is roughly 10 times more concentrated than can be normally determined, without dilution, by use of the free enzyme in solution. Also following from equation 3.27 is the independence of the reaction rate with respect to pH, ionic strength, temperature and inhibitors. This simply avoids the tricky problems often encountered due to the variability of real analytical samples (e.g, fermentation broth, blood and urine) and external conditions. Control of biosensor response by the external diffusion of the analyte can be encouraged by the use of permeable membranes between the enzyme and the bulk solution. The thickness of these can be varied with associated effects on the proportionality constant between the substrate concentration and the rate of reaction (i.e. increasing membrane thickness increases the unstirred layer () which, in turn, decreases the proportionality constant, kL, in equation 3.27). Even if total dependence on the external diffusional rate is not achieved (or achievable), any increase in the dependence of the reaction rate on external or internal diffusion will cause a reduction in the dependence on the pH, ionic strength, temperature and inhibitor concentrations.
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03-08-2012, 11:56 AM
biosensors.ppt (Size: 188 KB / Downloads: 30)
It is an analytical device which converts a biological response into an electrical signal.
It detects, records, and transmits information regarding a physiological change or process.
It determines the presence and concentration of a specific substance in any test solution.
To interact specifically with a target compound i.e. the compound to be detected.
It must be capable of detecting the presence of a target compound in the test solution.
The ability of a bio-element to interact specifically with target compound (specificity) is the basis for biosensor.
RESPONSE FROM BIO-ELEMENT
Heat absorbed (or liberated ) during the interaction.
Movement of electrons produced in a radox reaction.
Light absorbed (or liberated ) during the interaction.
Effect due to mass of reactants or products.
TYPES OF BIOSENSOR
Many chemical reactions produce or consume ions or electrons which in turn cause some change in the electrical properties of the solution which can be sensed out and used as measuring parameter.
(1) Amperometric biosensor
(2) Conductimetric biosensor
(3) Potentiometric biosensor
Glucose reacts with glucose oxidase(GOD) to form gluconic acid. Two electrons & two protons are also produced.
Glucose mediator reacts with surrounding oxygen to form H2O2 and GOD.
Now this GOD can reacts with more glucose.
Higher the glucose content, higher the oxygen consumption.
Glucose content can be detected by Pt-electrode.
APPLICATIONS OF BIOSENSOR
In food industry, biosensors are used to monitor the freshness of food.
Drug discovery and evaluation of biological activity of new compounds.
Potentiometric biosensors are intended primarily for monitoring levels of carbon dioxide, ammonia, and other gases dissolved in blood and other liquids.
Environmental applications e.g. the detection of pesticides and river water contaminants.
Determination of drug residues in food, such as antibiotics and growth promoters.
Glucose monitoring in diabetes patients.
Analytical measurement of folic acid, biotin, vitamin B12 and pantothenic acid.
Enzyme-based biosensors are used for continuous monitoring of compounds such as methanol, acetonitrile, phenolics in process streams, effluents and groundwater.
From all these studies, I conclude that biosensors are cheap, small, and portable devices.
They are capable of being used by semi-skilled operators.
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