A novel electrochemical biosensor for Hg2+ determination based on Hg2+-induced DNA hybridization

✍ Scribed by Xiangheng Niu; Yili Ding; Chen Chen; Hongli Zhao; Minbo Lan

• Publisher: Elsevier Science
• Year: 2011
• Tongue: English
• Weight: 600 KB
• Volume: 158
• Category: Article
• ISSN: 0925-4005
• DOI: 10.1016/j.snb.2011.06.040

✦ Synopsis

In this paper, a novel electrochemical biosensor for Hg 2+ determination based on Hg 2+ -induced DNA hybridization is reported. A pair of oligonucleotides with seven strategically placed thymine-thymine (T-T) mismatched bases was introduced. Firstly, one oligonucleotide (P1) modified with hexanthiol at 5-terminal was immobilized on a screen-printed gold electrode (SPGE) via self-assembly. Then the other oligonucleotide (P2) tagged with a ferrocene derivative as electroactive indicator was able to hybridize with P1 by forming thymine-Hg 2+ -thymine (T-Hg 2+ -T) complexes in the presence of Hg 2+ , providing a detectable electrochemical signal of the ferrocene derivative. However, when Hg 2+ was absent, the two oligonucleotides could not hybridize due to the T-T mismatched bases, and P2 could not be fixed on the electrode surface, with the indicator signal disappearing. Experimental results indicate that the proposed biosensor offers linear responses on Hg 2+ concentration in the range of 10-0.001 M, with a detection limit of 0.6 nM (S/N = 3). This new Hg 2+ -induced DNA hybridization strategy is demonstrated valid and efficient to detect trace Hg 2+ with high sensitivity and good selectivity.