Biosensors and Their Applications

It includes basic principle of biosensors, methods, types and applications of biosensors.

1. Unit I Chapter (C)
Biosensors-Working and applications of
biosensors in Pharmaceutical Industries
Dr. Mahesh Kumar Kataria
Professor, Seth G. L. Bihani S. D. College
of Technical Education, Sri Ganganagar
1Dr. Mahesh Kumar Kataria

2. Biosensors
Abiosensorisananalyticaldevicecontainingan
immobilizedbiologicalmaterial(enzyme,antibody,
nucleicacid,hormone,organelleorwholecell)whichcan
specificallyinteractwithananalyteandproducephysical,
chemicalorelectricalsignalsthatcanbemeasured.An
analyteisacompound(e.g.glucose,urea,drug,pesticide)
whoseconcentrationhastobemeasured.
Biosensorsbasicallyinvolvethequantitativeanalysisof
varioussubstancesbyconvertingtheirbiologicalsignals
intomeasurablesignals.Agreatmajorityofbiosensors
haveimmobilizedenzymes.Theperformanceofthe
biosensorsismostlydependentonthespecificityand
sensitivityofthebiologicalreaction,besidesthestabilityof
theenzyme.
2Dr. Mahesh Kumar Kataria

3. 1.LINEARITY:Linearityofthesensorshouldbehighforthedetectionof
highsubstrateconcentration.
2.SENSITIVITY:Valueoftheelectroderesponsepersubstrate
concentration.
3.SELECTIVITY:ChemicalsInterferencemustbeminimisedforobtaining
thecorrectresult.
4.RESPONSETIME:Timenecessaryforhaving95%oftheresponse.
Thefirstbiosensorwasinventedintheyear1950byAmerican
biochemistLelandCClark,isthefatherofbiosensor.Heinventedthe
glucosebiosensortodeterminetheglucoselevelinthesample.
3Dr. Mahesh Kumar Kataria

4. Characteristic features of a biosensor
a) Should be highly specific for the analyte.
b) Reaction used should be independent of manageable factors like
pH, temperature, stirring, etc.
c) Response should be linear over a useful range of analyte
concentrations.
d) Device should be tiny and bio-compatible.
e) Device should be cheap, small, easy to use and capable of
repeated use.
4Dr. Mahesh Kumar Kataria

5. MAIN COMPONENTS OF A BIOSENSOR
• Sensor, • Transducer, • Amplifier, • Processor, • Display unit
Sensor
It is a sensitive biological element (biological material (eg. tissue, microorganisms,
organelles, cellreceptors, enzymes, antibodies, nucleic acids, etc).
Transducer
Transducer is a device that converts energy from one form to another form. In
biosensors transducers convert the biochemical activity into electrical energy.
5Dr. Mahesh Kumar Kataria

6. General Features of Biosensors:
A biosensor has two distinct components.
1.Biologicalcomponent: enzyme, celletc.
2.Physicalcomponent: transducer,
amplifier etc.
The biological component recognizes and
interacts with the analyteto produce a
physical change (a signal) that can be
detected, by the transducer. In practice,
the biological material is appropriately
immobilized on to the transducer and the
so prepared biosensors can be repeatedly
used several times (may be around
10,000 times) for a long period (many
months).
6Dr. Mahesh Kumar Kataria

7. Principle of a Biosensor
Thedesiredbiologicalmaterial(usuallya
specificenzyme)isimmobilizedby
conventionalmethods(physicalormembrane
entrapment,non-covalentorcovalent
binding).Thisimmobilizedbiological
materialisinintimatecontactwiththe
transducer.Theanalytebindstothebiological
materialtoformaboundanalytewhichin
turnproducestheelectronicresponsethatcan
bemeasured.
Insomeinstances,theanalyteisconvertedto
aproductwhichmaybeassociatedwiththe
releaseofheat,gas(oxygen),electronsor
hydrogenions.Thetransducercanconvertthe
productlinkedchangesintoelectricalsignals
whichcanbeamplifiedandmeasured.
7Dr. Mahesh Kumar Kataria

8. Types of Biosensors
1. Electrochemical Biosensors:
AmperometricBiosensors
PotentiometricBiosensors
ConductometricBiosensors
2. Calorimetric Biosensor
3.Optical Biosensor
4.Piezo-electric Biosensor/Acoustic Biosensors
8Dr. Mahesh Kumar Kataria

9. 1. ELECTROCHEMICAL BIOSENSORS
Electrochemicalbiosensorsaresimpledevicesbasedonthemeasurementsof
electriccurrent,ionicorconductancechangescarriedoutbybioelectrodes.
1.1AmperometricBiosensors:
Thesebiosensorsarebasedonthemovementofelectrons(i.e.electric
current)asaresultofenzyme-catalysedredoxreactions.Normally,aconstant
voltagepassesbetweentheelectrodeswhichcanbedetermined.Inan
enzymaticreactionthatoccurs,thesubstrateorproductcantransferan
electronwiththeelectrodesurfacetobeoxidisedorreduced.
Thisresultsinanalteredcurrentflowthatcanbemeasured.Themagnitude
ofthecurrentisproportionaltothesubstrateconcentration.Clarkoxygen
electrodewhichdeterminesreductionofO2,isthesimplestformof
amperometricbiosensor.
Determinationofglucosebyglucoseoxidaseisagoodexample.Theglucose
oxidaseconvertsglucosetogluconicacidinthepresenceofglucoseoxidase
enzyme.Thedecreaseinglucoseisreadbypt/O
2electrode.Thedecreased
amountofO
2isdirectlyproportionaltotheglucoseconcentration.
9Dr. Mahesh Kumar Kataria

10. 1.2PotentiometricBiosensors:
Changesinionicconcentrationsaredeterminedbyuseof
ionselectiveelectrodes.pHelectrodeisthemostcommonlyused
ion-selectiveelectrode,sincemanyenzymaticreactionsinvolve
thereleaseorabsorptionofhydrogenions.Theotherimportant
electrodesareammonia-selectiveandCO
2selectiveelectrodes.
Thepotentialdifferenceobtainedbetweenthepotentiometric
electrodeandthereferenceelectrodecanbemeasured.Itis
proportionaltotheconcentrationofthesubstrate.Themajor
limitationofpotentiometricbiosensorsisthesensitivityof
enzymestoionicconcentrationssuchasH
+
andNH
+4
.
Ion-selectivefieldeffecttransistors(ISFET)arethelowcost
devicesthatcanbeusedforminiaturizationofpotentiometric
biosensors.AgoodexampleisanISFETbiosensorusedto
monitorintra-myocardialpHduringopen-heartsurgery.
10Dr. Mahesh Kumar Kataria

11. 1.3 ConductometricBiosensors:
There are several reactions in the biological systems
that bring about changes in the ionic species. These
ionic species alter the electrical conductivity which can
be measured. A good example of conduct metric
biosensor is the urea biosensorutilizing immobilized
urease.
Ureaseenzyme converts urea to NH
4
+
ions and HCO
3
-.
The concentration of NH
4
+
ions is read by electrode,
which is directly proportional to the urea present in
sample.
11Dr. Mahesh Kumar Kataria

12. 2. Thermal and Mass Calorimetric Biosensor
Severalbiologicalreactionsareassociatedwiththe
productionofheatandthisformsthebasisof
thermometricbiosensors.Iftheenzymecatalyzed
reactionisexothermic,twothermistorsmaybeused
tomeasurethedifferenceinresistancebetween
reactantandproductand,hence,theanalyte
concentration.
Adiagrammaticrepresentationofathermalbiosensor
isdepictedinFig.Itconsistsofaheatinsulatedbox
fittedwithheatexchanger(aluminiumcylinder).The
reactiontakesplaceinasmallenzymepackedbed
reactor.Asthesubstrateentersthebed,itgets
convertedtoaproductandheatisgenerated.The
differenceinthetemperaturebetweenthesubstrate
andproductismeasuredbythermistors.Evenasmall
changeinthetemperaturecanbedetectedbythermal
biosensors.
12Dr. Mahesh Kumar Kataria

13. 13
Example of Thermal and Mass Calorimetric Biosensor;
Thermometric biosensors are in use for the estimation of serum cholesterol.
When cholesterol gets oxidized by the enzyme cholesterol oxidase, heat is
generated which can be measured.
Determination of water content in food, jelly and fish.
Thermometric biosensors can be used as a part of enzyme-linked immunoassay
(ELISA) and the new technique is referred to as thermometric ELISA (T-ELISA).
Dr. Mahesh Kumar Kataria

14. 3. OPTICAL BIOSENSORS
Opticalbiosensorsarethedevicesthatutilizetheprincipleofoptical
measurements(absorbance,fluorescence,chemiluminescenceetc.).Theyemploy
theuseoffibreopticsandoptoelectronictransducers.Thewordoptrode,
representingacondensationofthewordsopticalandelectrodeiscommonlyused.
Opticalbiosensorsprimarilyinvolveenzymesandantibodiesasthetransducing
elements.Opticalbiosensorsallowasafenon-electricalremotesensingof
materials.Thesebiosensorsusuallydonotrequirereferencesensors,asthe
comparativesignalcanbegeneratedusingthesamesourceoflightasthesampling
sensor.
Anopticalbiosensorisacompactanalyticaldevicecontainingabiorecognition
sensingelementintegratedwithanopticaltransducersystem.Thebasicobjective
ofanopticalbiosensoristoproduceasignalwhichisproportionatetothe
concentrationofameasuredsubstance(analyte).Theopticalbiosensorcanuse
variousbiologicalmaterials,includingenzymes,antibodies,antigens,receptors,
nucleicacids,wholecellsandtissuesasbiorecognitionelements.Surfaceplasmon
resonance(SPR)andopticalwaveguideinterferometryutilizetheevanescentfield
incloseproximitytothebiosensorsurfacetodetecttheinteractionofthe
biorecognitionelementwiththeanalyte.Optocalfibersrequirefewmicroleterof
samplesfordetection.
Eg:Bloodgasmonitoring,respiratorygasmeasurement.
14Dr. Mahesh Kumar Kataria

15. 4. PIEZO-ELECTRIC BIOSENSORS/ACOUSTIC BIOSENSORS
Piezoelectricbiosensorsarebasedontheprincipleofacoustics(soundvibrations),hence
theyarealsocalledasacousticbiosensors.Piezoelectriccrystalsformthebasisofthese
biosensors.Thecrystalswithpositiveandnegativechargesvibratewithcharacteristic
frequencies.Adsorptionofcertainmoleculesonthecrystalsurfacealterstheresonance
frequencieswhichcanbemeasuredbyelectronicdevices.Enzymeswithgaseous
substratesorinhibitorscanalsobeattachedtothesecrystals.
Apiezoelectricbiosensorfororganophosphorusinsecticidehasbeendeveloped
incorporatingacetylcholineesterase.
Likewise,abiosensorforformaldehydehasbeendevelopedbyincorporating
formaldehydedehydrogenase.
Abiosensorforcocaineingasphasehasbeencreatedbyattachingcocaineantibodiesto
thesurfaceofpiezoelectriccrystal.
Ex.Antigenimmobilizedelectrodemaybeusedtodeterminethepresenceofspecific
antibodiesinthesample.Thenoiseofthesamplewillreduceafterbindingofthespecific
antibodieswiththeantigen,incomparisontothenoiseofthenonspecificantibody
presentinthesample.
LimitationsofPiezoelectricBiosensors:
Itisverydifficulttousethesebiosensorstodeterminesubstancesinsolution.Thisis
becausethecrystalsmayceasetooscillatecompletelyinviscousliquids.
15Dr. Mahesh Kumar Kataria

16. Applications of Biosensor
Biosensors in Food Industry
Biosensors in Medical field
Biosensors in Drug Discovery and Drug Analysis
Role of Biosensors in Environmental Monitoring
Paper based biosensor for water analysis
Epigenetics
Nanobiosensors
16Dr. Mahesh Kumar Kataria

17. 1.BiosensorsinFoodIndustry
Biosensorsareusedforthedetectionofpathogensinfood.
PresenceofEscherichiacoliinvegetables,isabioindicatorof
faecalcontaminationinfood.E.colihasbeenmeasuredby
detectingvariationinpHcausedbyammonia(producedby
urease–E.coliantibodyconjugate)usingpotentiometric
alternatingbiosensingsystems.
Enzymaticbiosensorsarealsoemployedinthedairyindustry.
2.BiosensorsinMedicalfield
Glucosebiosensorsarewidelyusedinclinicalapplicationsfor
diagnosisofdiabetesmellitus.
Anovelbiosensor,basedonhafniumoxide(HfO2),hasbeen
usedforearlystagedetectionofhumaninterleukin.
Thesearealsousedfordetectionofcardiovasculardiseases.
17Dr. Mahesh Kumar Kataria

18. 3.BiosensorsinDrugDiscoveryandDrugAnalysis
Enzyme‐basedbiosensorscanbeappliedinthepharmaceutical
industryformonitoringchemicalparametersintheproductionprocess
(inbioreactors).
Affinitybiosensorsaresuitableforhigh‐throughputscreeningof
bioprocess‐producedantibodiesandfordrugscreening.
Oligonucleotide‐immobilizedbiosensorsforinteractionsstudies
betweenasurfacelinkedDNAandthetargetdrugorforhybridisation
studies.
4.RoleofBiosensorsinEnvironmentalMonitoring
Thebiosensorsfindwideapplicationformeasurement,estimationand
controlofwater,airandsoilcontaminants.
Determinationofthepesticidescanbemadebypotentiometric
biosensor.
Amperometricbasicsensorcanbeusedforanalysesofwaterpollution
fromherbicide.
Concentrationofammoniacanbedefinedwithmicrobebiosensorwith
cellsoftypeNitrosomonassp.
18Dr. Mahesh Kumar Kataria

19. 5.PaperBasedBiosensorForWaterAnalysis
Presenceofcontaminantsinwaterisamajorconcern,contaminants
suchaspesticides,microorganisms,heavymetalsandchemicals
releasedbyvariousindustries.
Developmentofbiosensorshelpstodetectwatercontaminantsinfast,
accurateandrapiddetection.
Paperbasedbiosensoristhedevelopingtechniqueusedfor
analysingthewaterquality.
Paperanalyticaltechniqueincombinationwithbiosensor
servesasanewtechniqueforqualitativeandquantitative
analysisofwater.
Thekeyadvantageofthistechniqueisportable,lowcostandefficient.
6.Epigenetics
Photonicbiosensorshavebeendeveloped,whichcandetecttumorcell
inaurinesampletoanultra-sensitivitylevel.
Epigeneticmodificationsaredetectedafterexploitationofintegrated
opticalresonators(e.g.,post-translationalmodificationsinhistoneand
DNAmethylation)usingbodyfluidsofpatientssufferingfromcancer
orotherailments.
19Dr. Mahesh Kumar Kataria

20. 7.NANOBIOSENSORS
Advancesinnanotechnologyhaveledtothedevelopmentof
nanoscalebiosensorsthathaveexquisitesensitivityand
versatility.
Theultimategoalofnanobiosensorsistodetectanybiochemical
andbiophysicalsignalassociatedwithaspecificdiseaseatthe
levelofasinglemoleculeorcell.
Theycanbeintegratedintoothertechnologiessuchaslab-on-a
chiptofacilitatemoleculardiagnostics.
Theirapplicationsincludedetectionofmicroorganismsin
varioussamples,monitoringofmetabolitesinbodyfluidsand
detectionoftissuepathologysuchascancer.
20Dr. Mahesh Kumar Kataria

21. References:
VyasS.P.andDixitV.K.,PharmaceuticalBiotechnology,
FirstEdition,2005(reprint),C.B.S.Publishersand
Distributors,NewDelhi.
PatilA.S.etal.,ATextBookofPharmaceutical
Biotechnology,FirstEdition,2019,S.VikasandCompany,
Jalandhar.
RajeshGollapudiandSujithaPaladugu,Concisecoursein
PharmaceuticalBiotechnology,FirstEdition,2020,S.Vikas
andCompany,Jalandhar.
SikanderAliet.al.,“EnzymesImmobilization:An
OverviewofTechniques,SupportMaterialsandits
Applications”,InternationalJournalofScientific&
TechnologyResearch,6(9),2017
Mani V. M., Biosensors and its Applications, Islamiah
College (Autonomous),
21Dr. Mahesh Kumar Kataria

22. Important Questions
What are Biosensors?
Discuss basic principle of biosensors.
Explain the instrumentation and working of
biosensors.
Describe various types of biosensors.
Elaborate various applications of biosensors in
pharmaceutical industries.
22Dr. Mahesh Kumar Kataria