biosensor -jd

7/31/2019 biosensor -jd

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Biosensor

Submitted by:

Jyoti

10093004MSc nanotech-4 sem


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What is a Biosensor?


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Biosensor Any device that uses specific biochemical reactions todetect chemical compounds in biological samples.


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Current Definition

A sensor that integrates a biological element with a physiochemicaltransducer to produce an electronic signal proportional to a singleanalyte which is then conveyed to a detector.


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Components of a Biosensor

Detector


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CatalyticTransducer

Electrochemical

OpticalAcoustics/Mechanical

Calorimetric

Amplifier

Microelectronics

Electrical Signal

Buffer flow

Valve

Membrane

Waste

Affinity

Biocomponent

EnzymeOrganelleOrganism

AntibodyCell receptor

Nucleic acid

Data

Processing


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Father of the Biosensor

Professor Leland C Clark Jnr

19182005


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1916 First report on immobilization of proteins : adsorption of invertaseon activated charcoal

1922 First glass pH electrode

1956 Clark published his definitive paper on the oxygen

electrode.

1962 First description of a biosensor: an amperometricenzyme electrodre for glucose (Clark)

1969 Guilbault and Montalvo First potentiometric

biosensor :urease immobilized on an ammoniaelectrode to detect urea

1970 Bergveld ion selective Field Effect Transistor (ISFET)

1975 Lubbers and Opitz described a fibre-optic sensor with immobilised indicatorto measure carbon dioxide or oxygen.

History of Biosensors


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1975 First commercial biosensor ( Yellow springs

Instruments glucose biosensor)

1975 First microbe based biosensor, First immunosensor

1976 First bedside artificial pancreas (Miles)

1980 First fibre optic pH sensor for in vivo blood gases(Peterson)

1982 First fibre optic-based biosensor for glucose

1983 First surface plasmon resonance (SPR)immunosensor

1984 First mediated amperometric biosensor:ferrocene used with glucose oxidase for glucose

detection



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1987 Blood-glucose biosensor launched by

MediSense ExacTech

1990 SPR based biosensor by Pharmacia BIACore

1992 Hand held blood biosensor by i-STAT

1996 Launching of Glucocard

1998 Blood glucose biosensor launch by LifeScanFastTake

1998 Roche Diagnostics by Merger of Roche and

Boehringer mannheim

Current Quantom dots, nanoparicles, nanowire,nanotube, etc



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Advances in several areas have led to development of Biosensors:

Techniques for stabilizing enzymes/cells/Ab on to the surface ofsolid support while retaining their biological activity(Immobilization Technology)

Development of tailor made membranes ( Membrane Technology) Integration of biomolecules and microelectronics/information

technology (Semi conductor Industry)


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Advantages of successful biosensor

Little sample consumption,high sampling rates, and relativelyflexible and simple experimental set-up.

Fast response time.

Compactness due to miniaturisation.

Parallel determination of more than one components.

Reusability and disposability.

Leads to predictable shelf life.

Helps to achieve better quality and safety control,along withsaving of time,energy,money and man-power.


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Disadvantages of biosensor :

Limited availability.

Limited testing life due to biological character of their design.

Complexity and variability of the food samples have caused difficulty intheir scale-up.

Problems in mass production of biosensor components-immobilized

biologically sensitive material and transducing system.


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1. LINEARITY Linearity of the sensor should be highforthe detection of high substrate

concentration.2. SENSITIVITY Value of the electrode response persubstrate concentration.

3. SELECTIVITY Chemicals Interference must beminimised for obtaining the correct

result.4.RESPONSE TIME Time necessary for having 95%

of the response.

Basic Characteristics of aBiosensor


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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


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4. Signal

(How do you know there was a detection)

3. Detection/Recognition

(How do you specifically recognize the analyte?)


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PRINCIPLE OF BIOSENSOR

A biosensor is an analytical measuring tool comprised of a biological element ofknown molecular properties tightly coupled to a physical transducer responsible

for converting the biological signal into quantifiable information. Therefore, the biosensor selectivity is induced by the immobilization, in the

sensitive area of the detector, of the biological component (enzyme, DNAreceptor, antibody, antigen, microorganism, cell, etc.) specific to the targetanalyte.

The molecular recognition then corresponds to the association of the biological

element and its target molecule (analyte) through an association such as:enzyme-substrate, antibody-antigen, receptor-hormone, complementary DNAsequencing, etc. These associations maximize the capacity of the biomoleculesto recognize a unique substance among various substances.

The combinations of recognition-transducer systems are numerous and thisexplains the many definitions and nomenclatures of these types of sensors. Themain methods of transduction that are the most current and well developed,

from both a fundamental and experimental point of view, are: electrochemical,optical, acoustic and thermal.


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COMPONENTS OF A BIOSENSOR

Physical components

Biological components


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(i) TRANSDUCER

A transducer converts the biochemical signal to

an electronic signal. The signal produced may be

in the form of electrochemical (change inpotential or current), optical (color change),

calorimetric (heat measurement), piezoelectric

(mass change) response etc.

Physical components


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(ii) AMPLIFIER

The electronic signal produced by transduceris very small & is amplified by an amplifier.

(iii) MICROPROCESSOR

The amplified signal is fed in to themicroprocessor. The signal is then

processed & interpreted & is displayed in

suitable units.


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Biological components

Enzymes

These may be used in purified form or may be present in microorganisms or inslice of intact tissue. They are biological catalyst for particular reactions and canbind themselves to specific substrate. This catalytic action is made use of in thebiosensor.

Antibodies

They will bind specifically with the corresponding antigen. They have nocatalytic activity. Despite this, they are capable of developing ultra high

sensitivity in biosensors. Nucleic acids

They operate selectively because of their base pair characteristics.

Receptors

Inside the lipid bilayer plasma membrane surrounding a cell are protein than

transfer the full breadth of the membrane and which have molecularrecognitionproperties. They are difficult to isolate but will bind solutes withhigh degree of affinity and specificity matching antibodies.


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The biological component interacts specifically tothe analyte, which produces a physical change

close to the transducer surface. This physicalchange may be:-

Heat released or absorbed by the reaction(measured by calorimetric biosensor).

Production of an electrical potential due tochanged distribution of electrons (potentiometricbiosensors).

Movement of electrons due to redox reaction(amperometric biosensor).

Light produced or absorbed during the reaction(optical biosensor).


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OTHER COMPONENTS OF A BIOSENSOR SYSTEM

ANALYTE/SUBSTRATEf: It is compound whose conc. is to be

determined by the biosensor, either by being consumed orproduced in a biochemical process. Among the analytesdetectable with biosensors are carbohydrates, organic acids,alcohols, phenols, amines, heterocyclic compounds, proteins,enzymes cofactors, inorganic ions, hormones, vitamins,peptides, drugs, xenobiotics, microorganisms, gases, andpesticides. Analyte concentrations measurable with varioustypes of biosensors range rom 10-7 molL-1 (biocatalyticsensor) to as little as 10-15 molL-1 (affinity sensors).

MEMBRANES:A membrane that is selectively permeablenormally protects the receptor. The art of membrane

construction, though relatively new, is rapidly evolving tomeet the needs of commercial biosensor construction. It ishighly specialized, involving techniques from simple solutioncasting to spin- and spray- coating, and interfacialpolymerization together with electropolymerisation at a

surface.


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CLASSIFICATION OF BIOSENSORS

Based on the level of integration

Based on transducer system

Based on sensing element


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inBased on the level of integration

FIRST GENERATION BIOSENSORSIn case of these biosensors, the biocatalyst is eitherbound to or entrapped in a membrane, which in turn isfixed on the surface of the transducer.

SECOND GENERATION BIOSENSORSThese biosensors involve the adsorption of covalentfixation of the biologically active component to thetransducer surface.

THIRD GENERATION BIOSENSORSIn these biosensors the biocatalyst is directly binded to

an electronic device that transduces and amplifies thesignals.


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BASED ON TRANSDUCER

Electrochemical biosensors

Optical biosensors

Calorimetric biosensors

Piezoelectric biosensors

Thermal biosensors

ucer system


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Electrochemical biosensors

The biological signal can be used to generate a

current or charge or may change conductivity

between two electrodes and therefore the

corresponding transduction device has been

described as

Amperometric,

Potentiometric

Conductometric


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Optical biosensors

Optical biosensors are based on the measurement

of the light absorbed or emitted as consequence of

a biochemical reaction. In such type of biosensors,light waves are guided by means of optical fibers to

suitable detectors.

These types of biosensors have been used for the

detection of pH, O2 and CO.


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Calorimetric biosensors

The basic principle of such biosensor is that

all biochemical reactions is involve a change

in enthalpy such a change in enthalpy is

detected by calorimetric biosensors fordetection, Thermal signal generated by the

redox reaction was measured as opposed to

measuring the electrochemical signal.


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Piezoelectric biosensors

These biosensors operate on the principle of

generation of electric dipoles on subjecting

anisotropic natural crystal to mechanical

stress.

Such type of biosensors utilized for the

measurement of NH3, H2, CH4, CO & other

organophosphorous compounds. This is alsocalled as acoustic wave biosensor.


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Thermal biosensors

Thermometric devices predominantly

measure the changes in temperature of the

circulating fluid following the reaction of a

suitable substrate with the immobilizedenzyme molecules.


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Based on sensing element Catalytic Biosensors

Enzyme and microbial cell based biosensors come in thiscategory. The immobilized sensing biomolecule act as a catalystand catalyze the biochemical reaction. Various examples ofcatalytic biosensors are Glucose Biosensor (glucose oxidasebased), Cholesterol biosensor (cholesterol oxidase andcholesterol esterase based), Urea biosensor (urease based),

Lactate biosensor (lactate oxidase and lactate dehydrogenase)etc.

Affinity Biosensors

This type of biosensors exploits the affinity between the analyteand biocomponent immobilized onto the sensor surface.

Biomolecules such as antibodies, nucleic acids, lectins andhormone receptors, are used to bind complementary moleculesirreversibly and non-covalently. The basic principle behind theaffinity biosensors is that the analyte must be thecomplementary to the immobilized biocomponent.Immunosensors and DNA biosensors are usually the most studiedin this category.


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MATRIX FOR BIOSENSOR FABRICATION A number of matrices have been used for the

immobilization of biomolecules to improve their

activity and stability.

Example:

- Conducting polymers.

- Sol-gel matrices.

- Nanomaterials.- Composites of nanomaterials and

conducting polymer.


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Methods of immobilization

Adsorption

Microencapsulation

Entrapment

Covalent attachment

Cross linking


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Advantages of biosensors

High selectivity and specificity

High sensitivity

Fast respose time

Simple to use

Comparatively low operation cost

Miniaturization

Disposibility


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Disadvantages of biosensors

Limited availability

Instability

Limited shelf life

Sensitivity to interference and contamination

Applications


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Applications

Clinical diagnosis and biomedicine

Food and drink production and analysis

Pharmaceutical and drug analysis

Industrial effluent control

Pollution control and monitoring

Mining, industrial and toxic gases

Military applications Farm, garden and veterinary analysis

Process control: fermentation control and analysis

Microbiology: bacterial and viral analysis


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Applications of Biosensors

Continuous monitoringSensitive Detection of nutrients/other parametersCan be incorporated into Products to monitor

Temperature abuseShelf lifeContamination, and

To provide visual indicator to consumers of the state ofthe product at the time of purchase


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Commercially available Biosensors for Food Analysis

Analyte Biocomponent Application

Lactose -Galactosidase Raw milkSucrose Invertase Instant cocoa manufacture

Lactate Lactate DH Dairy products, Yoghurt, whey

Ethanol ADH Alcoholic beverages

Amino acids Amino acid DH Many foodsGlutamate L- Glu oxidase Soy sauce manufacture

Ascorbic acid Ascorbate oxidase Fruit juices

Pencillin Ab- enz conjugate Milk

PHB ester P- OH Benzoatehydroxylase

Fruit juices & drinks

Sulfite Sulfite oxidase Dry fruits, wine, vinegar.

Aspartame L-aspartase/ Al. oxidase Many foods (level of sweetener)

Glucose Glu oxidase Fruit juices, molasses, Brewing etc


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Its applications include:

Bitterness Measurement of New Chemical Entities

Bitterness Masking Efficiency

Matching Placebo Development (same taste of drug)

Shelf-life & Stability of Formulations

Comparison with Competitor Products

Scale-up of Formulation Process

Screen for best Additive & Taste agents

ELECTRONIC TONGUE


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The US Department of Agriculture (USDA) is testing the zNosetechnology to see whether the sensor devices can pick up buginfestation in plants. The zNose could have a wider use forfood and beverage companies, such as for aroma chemistry

testing or for the analysis of wine and beer. The zNose isunique in its ability to separate and quantify the chemistryof any fragrance, odor or chemical vapor with part per-trillion sensitivity within 10 seconds.

ELECTRONIC NOSE
http://www.foodproductiondaily-usa.com/search/search.asp?KEYWORDS=znose&period=allhttp://www.foodproductiondaily-usa.com/search/search.asp?KEYWORDS=sensor&period=allhttp://www.foodproductiondaily-usa.com/search/search.asp?KEYWORDS=sensor&period=allhttp://www.foodproductiondaily-usa.com/search/search.asp?KEYWORDS=znose&period=all


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A researcher examines a

capillary column used as an

electrochemical sensor to

detect harmful bacteria in

food products. Suchsensors promise to speed

up detection of harmful

bacteria in food processing

industries.


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Electroimmunoassay technology is composed of a circuitwith a capture antibody attached to the solid surface in thearea of the electrode gap


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HAND HELD MODEL OF A BIOSENSOR


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Using a DNA-based cell adhesionsystem, researchers have created cellchips (self-assembled arrays of cells ona thumbnail-sized chip), analagous toDNA chips, that could be used asbiosensors for detecting the presenceof pathogens.

A new technique in which single strands of synthetic DNA are used tofirmly fasten biological cells to non-biological surfaces has been

developed by researchers with the Lawrence Berkeley NationalLaboratory (Berkeley Lab) and the University of California at Berkeley.


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BIOSENSORS FOR PACKAGES ARE BEING DEVELOPEDWHICH CAN NOT ONLY INDICATE THE FRESHNESS OF FOODSINSIDE THE PACKAGE BUT ALSO DETECT THE PRESENCE OFPATHOGENIC MICROORGANISMS AND THEIR TOXINS


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Work is being done on RFID biosensors, which couldbe implanted into body to monitor the body functions

of patients

A pateints left hand with the planned location of the RFID chip
http://wiki/Image:RFID_hand_1.jpg


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BIOSENSOR USED FOR ENVIRONMENTAL MONITORING


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New biosensor device developed by University of Rhode Island to detects

Salmonella, E. coli, and other bacteria. The biosensor uses fiber optic technology to

quickly and accurately detect and quantify bacteria levels in meats, poultry and other

foods.

The latest version also uses microscopic magnetic beads called

microspheres. The surface of the beads are covered with antibodies thatcollect the pathogen and are then labeled with a fluorescent dye. Thenthe beads are magnetically focused in front of optical fibers and a lasersignal reports the pathogen concentration.


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Wearable Biosensors

Ring Sensor

Smart Shirt


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Biosensors on the Nanoscale

Molecular sheaths around the nanotube are developed thatrespond to a particular chemical and modulate thenanotube's optical properties.

A layer of olfactory proteins on a nanoelectrode react withlow-concentration odorants (SPOT-NOSED Project).Doctors can use to diagnose diseases at earlier stages.

Nanosphere lithography (NSL) derived triangular Agnanoparticles are used to detect streptavidin down to

one picomolar concentrations.

The School of Biomedical Engineering has developed an anti-body based piezoelectric nanobiosensor to be used foranthrax,HIV hepatitis detection.


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hank you!

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