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This digital document is a journal article from Analytica Chimica Acta, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.
Description:
Development of an electrochemical DNA biosensor based on a human interleukine-2 (IL-2) gene probe, using a pencil graphite electrode (PGE) as transducer and methylene blue (MB) as electroactive label is described. The sensor relies on the immobilization of a 20-mer single stranded oligonucleotide probe (hIL-2) related to the IL-2 gene on the electrode. The hybridization between the probe and its complementary sequence (chIL-2) as the target was studied by square wave voltammetry (SWV) of MB accumulated on the PGE. In this approach the extent of hybridization is evaluated on the basis of the difference between SWV signals of MB accumulated on the probe-PGE and MB accumulated on the probe-target-PGE. Some hybridization experiments with non-complementary oligonucleotides were carried out to assess whether the suggested DNA sensor responds selectively to the target. Some experimental variables affecting the performance of the biosensor including: polishing of PGE, its electrochemical activation conditions (i.e., activation potential and activation time) and probe immobilization conditions on the electrodes (i.e., immobilization potential and time) were investigated and the optimum values of 1.80V and 300s for PGE activation, and -0.5V and 400s for the probe immobilization on the electrode were suggested.