Electrochemical Detection of Lead Using Target-Induced Strand Release Strategy

20 Dec 2012

Pui Sai Lau is a guest web writer for Analyst. She is currently a PhD student at McMaster University, Hamilton, ON, Canada.

Electrochemical Sensing Using Target-Induced Strand Release

The toxic, bioaccumulative, and non-biodegradable effects of heavy metals pose a severe environmental concern. Hence, monitoring toxic metals such as lead requires effective detection methods. Bo Tang and colleagues from the Shandong Normal University, China, have developed the latest electrochemical detection strategy, which is based on the target-induced strand release method. In their design, the lead-binding DNA aptamer forms a duplex with a complementary DNA sequence that is immobilized to an electrode surface. In this state, methylene blue redox indicators are able to intercalate along the duplex structure, and provide a readable electrochemical signal. However, in the presence of lead, the metal ions bind specifically to the aptamer, which allows release of the lead-aptamer complex into solution. The subsequent release of methylene blue molecules away from the electrode surface leads to a measurable decrease in signal to signify lead detection.