Microchimica Acta

, Volume 169, Issue 3–4, pp 335–343 | Cite as

Optimization of acetylcholinesterase immobilization on microelectrodes based on nitrophenyl diazonium for sensitive organophosphate insecticides detection

  • Ovidiu Ilie Covaci
  • Bogdan Bucur
  • Madalina Petruta Bucur
  • Gabriel Lucian Radu
Original Paper


The immobilization of acetylcholinesterase on platinum microelectrodes modified with p-nitrobenzenediazonium is optimized. In the first step, a layer of p-nitrophenyl groups was deposited on the surface and then reduced to p-aminophenyl groups. Finally, the enzyme was linked to the amino groups on the surface using glutaraldehyde. Each step of the electrode modification was characterized by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) at acidic and neutral pH to modify the electric charges of different bound moieties. The deposition of diazonium groups was attempted by potentiometry, amperometry or CV, but only potentiometry proceeded without passivation of the surface. The use of microelectrodes improved the limit of detection of ethylparaoxon measurements to 20 nM (compared to 100 nM in case of screen-printed electrodes based on the same method of immobilization). The method allowed the production of stable and reproducible amperometric microbiosensors and may be adapted to other enzymes and electrode materials.


Microelectrode Diazonium salt Enzyme immobilization Enzymatic microbiosensor 



This work was supported by Romanian Ministry of Education and Research through Grants MICROSEN 11049/2007 and SAFEFOOD 61-030/2007. Ovidiu Ilie Covaci is a Ph. D. student with an AMPOSDRU scholarship.

Supplementary material

604_2010_336_MOESM1_ESM.doc (2.8 mb)
ESM 1 (DOC 2.82 mb)


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Ovidiu Ilie Covaci
    • 1
  • Bogdan Bucur
    • 2
  • Madalina Petruta Bucur
    • 2
  • Gabriel Lucian Radu
    • 1
  1. 1.Applied Chemistry and Materials Science FacultyPolytechnica University of BucharestBucharestRomania
  2. 2.National Institute of Research and Development of Biological SciencesBioanalysis CenterBucharestRomania

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