Sensitive electrochemical detection of hydroxyl radical with biobarcode amplification

By using biobarcode nanoparticles, we have successfully constructed a DNA-based biosensor for amplified electrochemical detection of hydroxyl radical (center dot OH). Thiolatecl DNA1 (SH-DNA1) was firstly immobilized on the planar gold (Au) electrode. center dot OH generated from Fenton reaction could induce serious oxidative damage of the DNA layer adsorbed on the electrode surface, which was monitored by an intercalating probe, methylene blue (MB). In order to enhance the sensitivity of the biosensor, DNA2-functionalized Au nanoparticles (DNA2-AuNPs) were used to amplify the response signal. The developed DNA-based biosensor could detect center dot OH quantitatively with wide linear range up to 10 mM and low detection limit of 3 mu M, and exhibited satisfactory selectivity. On the other hand, this electrochemical biosensor could have potential application in the evaluation of antioxidant capacity. (C) 2012 Elsevier B.V. All rights reserved.