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Experimental Studies on the Application of Biosensors for Detection of Toxic Compounds

Ghadiri, Mohammad | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40451 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Roosta Azad, Reza; Kariminia, Hamid Reza
  7. Abstract:
  8. In this project, quantification of sulfide ion was investigated based on peroxidase enzyme inhibition. The fungal peroxidase was obtained from the liquid culture of Coprinus cinereus NBRC 30628. Two different biosensing systems were suggested for sulfide ion measurement: (1) An amperometric inhibition peroxidase biosensor proposed for determination of sulfide by in situ bulk polymerization of acrylamide for immobilization of peroxidase on screen-printed carbon electrode. Measurements were performed using phosphate buffer solution as a supporting electrolyte in the presence of hydroquinone as a mediator. Identification method was based on reduction of generation current, caused by hydrolysis of H2O2 by peroxidase. This reduction is due to inhibition of peroxidase by sulfide. The developed biosensor determinates sulfide in the range of 4 to 26 µM with a detection limit of 3.7 µM. (2) A spectrophotometirc detection of sulfide applying peroxidase immobilized on sodium alginate was examined. The sensing scheme was based on the decrease of the absorbance of the orange compound produced from substrates, pyrogallol and H2O2, due to the inhibition of peroxidase by sulfide. Absorbance of the compound was detected at 420 nm with a spectrophotometer. Sulfide was successfully detected in the concentration range of 0.5 to 7 µM with a detection limit of 0.29 µM. The kinetic parameters of Michaelis–Menten with and without sulfide were also calculated and possible inhibition mechanism was deduced according to the variation of parameters.

  9. Keywords:
  10. Biosensor ; Inhibition ; Sulfide Measurement ; Amperometric Method ; Enzymatic Inhibition

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