1 / 17

Amperometric Biosensors

Amperometric Biosensors. Introduction. Enzyme Catalyzed redox reactions The function of the enzyme is to generate or consume an electroactive species in a stoichiometric relationship with its substrate or target analyte

Download Presentation

Amperometric Biosensors

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Amperometric Biosensors

  2. Introduction • Enzyme Catalyzed redox reactions • The function of the enzyme is to generate or consume an electroactive species in a stoichiometric relationship with its substrate or target analyte • Amperometric transducer allows for the electrometrical reactions to proceed at the electrode surface, thus giving rise to a current

  3. Introduction - Amperometric Biosensor Schematic

  4. Introduction S+C enzyme P + C’ S = Substrate C = Cofactor / Coreactant P = Product C’ = Cofactor Product

  5. Introduction • Three generations • 1st generation: the normal product of the reaction diffuses to the transducer and causes electrical response • 2nd generation: involves specific mediators between reaction and transducer to generate improved response

  6. Introduction • 3rd generation: reaction itself causes the response

  7. Amperometric Glucose Biosensor • Developed by Updike and Hicks • First reported use of enzyme electrode • Glucose in blood-diagnosis of diabetes • O2 detection • H2O2 detection • Enzyme mediation

  8. Glucose Biosensor – O2 • Central – Pt cathode, surrounding Ag/AgCl anode, KCl electrolyte solution • Teflon membrane • Cathode (0.6V) O2 + 4H+ +4e- 2H2O • Anode 4Ag + 4Cl- 4AgCl + 4e- • Glucose +O2 glucoseoxidase Gluconic acid + H2O

  9. Glucose Biosensor – O2

  10. Glucose Biosensor – H2O2 • Reverse polarity of electrodes for the O2 set up • Replace Teflon membrane with cellulose acetate membrane • Cathode: 2Ag + 2Cl- 2AgCl + 2e- • Pt Anode (0.6V): H2O2 O2+2H+ + 2e- • Counter electrode: 4H++O2 2H2O – 4e-

  11. Glucose Biosensor – H2O2

  12. Glucose Biosensor – redox mediators • Replace O2 with synthetic e- acceptor to shuttle e- from the flavin redox center of the enzyme to the electrode • Measurements become insensitive to O2 fluctuations, and can be carried out at lower potentials • Enzyme mediators – dimethyl ferrocene, medola blue

  13. Glucose Biosensor – Redox mediators Glucose + Gox(FAD) gluconic acid + Gox(FADH2) Gox(FADH2)+2Mox Gox(FAD)+2Mred+2H+ 2Mred 2Mox + 2e-

  14. Common Enzyme electrodes

  15. Some Commercial applications • YSI : Glucose/Lactate • Prostate specific antigen (PSA) • NOVA Bioprofile analyzer (PO2, Gluc, Gln, Glu, Lactate)

  16. Other Applications • Glucose: meat freshness, fermentation • Rapid cell number monitor • Monitor of herbicides in surface waters • Amperometric and novel fluorescent DNA probes • Rapid electrochemical sensor for Iron

  17. References • A.G. Elie,Principles of Potentiometric and Amperometric Biosensors,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

More Related