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EEE 529 Microsystems Amperometric Biosensors

EEE 529 Microsystems Amperometric Biosensors. Agamyrat Agambayev 520112003. Contents :. Introduction to Biosensors Definitions Amperometric Biosensors Generations of Amperometric Biosensors Performance factors Applications References. MULTIDISCIPLINARY NATURE OF BIOSENSOR :.

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EEE 529 Microsystems Amperometric Biosensors

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  1. EEE 529 MicrosystemsAmperometric Biosensors AgamyratAgambayev 520112003

  2. Contents: IntroductiontoBiosensors Definitions AmperometricBiosensors Generations of AmperometricBiosensors Performancefactors Applications References

  3. MULTIDISCIPLINARY NATURE OF BIOSENSOR:

  4. INTRODUCTION BIOSENSORS : Compact analytical devices that bring together the use of abiological, a biologically-derived or a biomimic element to recognize the analyte.

  5. INTRODUCTION Biosensor = biorecognation element + transducer.  Biorecognation element a biomolecule that recognizes the target analyte Transducer converts the recognition event into a measurable signal The uniqueness of a biosensor is that the two components are integrated into one single sensor 

  6. INTRODUCTION Biosensor = biorecognation element + transducer. 

  7. Biosensor = biorecognation element + transducer. Transducer. A transducer should be capable of converting the biorecognition event into a measurable signal . Typically, this is done by measuring the change that occur in the bioreceptor reaction. For example, the enzyme glucose oxidase (used as a bioreceptor in a glucose biosensor) catalyzes the following reaction: Glucose + O2 --------> Gluconic acid + H2O2

  8. To measure the glucose concentration, 3 different transducers can be used: • An oxygen sensor that measures oxygen concentration • A pH sensor that measures the acid (gluconic acid) production • A peroxide sensor that measures H2O2 concentration. • Note: • An oxygen sensor is a transducer that converts oxygen concentration into electrical current. • A pH sensor is a transducer that converts pH change into voltage change. • A peroxidase sensor is a transducer that converts peroxidase concentration into an electrical current.

  9. The choice of the biological recognition element is the crucial decision that istaken when developing a novel biosensor design. • It is important to define criteriafor, for example, a suitable redox enzyme for a specific biosensor. • Most importantly,the enzyme needs to selectively react with the analyte of interest. • The redoxpotential of the primary redox center needs to be within a suitable potentialwindow (usually between − 0.6 and 0.9 V vs. Ag/AgCl). • The enzyme needs to bestable under the operation and storage conditions of the biosensor and shouldprovide a reasonable long - term stability.

  10. AdvantagesandDisadvantages of usingEnzymes in sensors ADVANTAGES DISADVANTAGES • Highlyselective • Catalyticallyactiveimprovesensitivity • Fairlyfast-acting • One of themostknownbiologicalcomponents • Expensive • A lossactivitywhenimmobilized on a transducer • Tendingtoloseactivityafter a relativelyshortperiod time

  11. Considerations forbiosensordevelopment • Selection of a suitable biorecognationmolecule • Selection of a suitable immobilization method • Selection of a suitable transducer • Designing of biosensor considering measurement range,linearity, and minimization of interference • Packaging of biosensor

  12. Biosensors are classified according to the parameter that • is measured by the physicochemical transducer of the biological event as: • Optical, • Electrochemical ---- >Amperometric • Acoustic, • Thermal. • AmperometricBiosensors: the oldest ones, which have led to the highernumber of readyto-use devices, are based on the monitoring of electron-transfer processes

  13. Redox (reduction-oxidation) reactions include all chemical reactions in which atomshave their oxidation state changed. 

  14. Amperometric Biosensors produce a current proportional to the concentration of the substance to be detected. The most common amperometric biosensors use the Clark Oxygen electrode. In the glucose Amperometric Biosensor, the Clark Oxygen electrode is separated from glucose by a membrane, that is permeable to oxygen. A biocatalyst Glucose Oxidase(GOD) is housed between this membrane and another membrane that separates it from the glucose. This membrane that separates GOD and glucose is permeable to both Oxygen and Glucose.

  15. In effect, the enzyme GOD is immobilized between two membranes, the top being permeable only to oxygen and the bottom to both Oxygen and Glucose. The Glucose that enters the membrane is Oxidised in presence of the enzyme GOD, to produce Glucuronic acid and Hydrogen Peroxide. glucose + O2 –>  glucuronic acid + H2O2 Hence the concentration of oxygen decreases as it moves up through the membranes to reach the cathode. This decrease in Oxygen concentration is reflected as a decrease in current between the electrodes.

  16. Alternatively, the decrease in the concentration of Hydrogen Peroxide can also be used to find the concentration of glucose, by changing the voltage applied between the electrodes to +0.68 V relative to the Ag/AgCl electrode causing the reactions: Pt anode     H2O2-- > O2 + 2H+ + 2e- Ag cathode     2AgCl + 2e--- > 2Ag0 + 2Cl-

  17. 1stgeneration: the normal product of the reactiondiffuses to the transducer and causes electrical response

  18. 1stgeneration: the normal product of the reactiondiffuses to the transducer and causes electrical response

  19. 1stgeneration: the normal product of the reactiondiffuses to the transducer and causes electrical response

  20. 1stgeneration: the normal product of the reactiondiffuses to the transducer and causes electrical response

  21. 2ndgeneration: involves specific mediators between reaction and transducer to generate improved response

  22. 2ndgeneration: involves specific mediators between reaction and transducer to generate improved response

  23. 2ndgeneration: involves specific mediators between reaction and transducer to generate improved response

  24. 2ndgeneration: involves specific mediators between reaction and transducer to generate improved response

  25. 2ndgeneration: involves specific mediators between reaction and transducer to generate improved response

  26. 2ndgeneration: involves specific mediators between reaction and transducer to generate improved response

  27. 3rd generation: reaction itself causes the response

  28. 3rd generation: reaction itself causes the response

  29. AMPEROMETRIC BIOSENSORS

  30. PERFORMANCE FACTORS • Selectivity • Sensitivity • Accuracy • Response time • Recovery time • Lifetime

  31. PERFORMANCE FACTORS

  32. References • A.G. Elie,Principles of Potentiometric and AmperometricBiosensors,University of Virginia,(2002) • P.V. Climent, M.L.M.Serralheiro, and M.J.F. Rebelo, Pure and Applied Chemistry 73, pp.1993-1999, 2001 • http://www.lsbu.ac.uk.html • http://www.gatewaycoalition.org/files/Hidden/sensr/tocsenf.htm • http://techramble.wordpress.com/2009/08/03/amperometric-biosensors/ • http://www.lbb.ethz.ch/Education/Biosensors/2011FSlesson4TZ

  33. ThankYou

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