Article

Impedance Spectroscopy and Biosensing

Biosystems Technology, Wildau University of Applied Sciences, Bahnhofstrasse 1, 15745 Wildau, Germany.
Advances in Biochemical Engineering/Biotechnology (Impact Factor: 1.66). 02/2008; 109:195-237. DOI: 10.1007/10_2007_081
Source: PubMed

ABSTRACT

This chapter introduces the basic terms of impedance and the technique of impedance measurements.
Furthermore, an overview of the application of this transduction method for analytical purposes will be
given. Examples for combination with enzymes, antibodies, DNA but also for the analysis of living cells
will be described. Special attention is devoted to the different electrode design and amplification schemes
developed for sensitivity enhancement. Finally, the last two sections will show examples from the label-free
determination of DNA and the sensorial detection of autoantibodies involved in celiac disease.

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    ABSTRACT: Enzymatic conductometric biosensor, using immobilized Arthrospira platensis cells on gold interdigitated electrodes, for the detection of pesticides in water, was elaborated. Cholinesterase activity (AChE) was inhibited by pesticides and a variation of the local conductivity was measured after addition of the substrate acetylthiocholine chloride (AChCl). The Michaelis-Menten constant (Km) was evaluated to be 1.8 mM through a calibration curve of AChCl. Inhibition of AChE was observed with paraoxon-methyl, parathion-methyl, triazine and diuron with a detection limit of 10(-18) M, 10(-20) M, 10(-20) M and 10(-12) M, respectively and the half maximal inhibitory concentration (IC50) was determined at 10(-16) M, 10(-20) M, 10(-18) M and 10(-06) M, respectively. An important decrease of response time τ90% was recorded for AChE response towards AChCl after 30 min cell exposure to pesticides. Scanning electron microscopy images revealed a degradation of the cell surface in presence of pesticides at 10(-06) M.
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    • "Electrochemical methods such as electrochemical impedance spectroscopy (EIS) are spreading rapidly due to their quick operation and simplicity in the field of chemical and biosensing [1]. Gold thin films are often used as working electrodes due to their several preferable properties, such as the relatively simple surface chemistry methods to chemically attach receptors on the electrode surface. "
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