Analytical Sciences

Detection of Pb²⁺ in Aqueous Solution by Using a DNA-modified Microcantilever

Rong-Peng PENG,*,**,*** Ling-Bao XING,* Xiao-Jun WANG,* Cheng-juan WU,* Bin CHEN,* Hai-Feng JI,*** Li-Zhu WU,* and Chen-Ho TUNG*

*Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences and Graduate University of Chinese Academy of Sciences, Beijing 100190, China
**College of Chemistry, Nanchang University, Nanchang 330031, Jiangxi, China
***Department of Chemistry, Drexel University, Philadelphia, Pennsylvania, 19010, USA

We developed a novel Pb²⁺-sensor based on a microcantilever that was modified with a specific Pb²⁺-dependent DNAzyme molecule. This microcantilever sensor could detect Pb²⁺ sensitively and selectively in an aqueous solution. Upon complexation with Pb²⁺, the DNAzyme duplex unwinded and formed a G-quadruplex conformation, which led to an increase of repulsion between the DNAzyme molecules and a subsequent bending of the microcantilever. This microcantilever sensor could be regenerated, flowing through a strong Pb²⁺ chelator, 1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid. The detection limit of the microcantilever sensor for Pb²⁺ ions is as low as 10⁻⁸ M. The microcantilever sensor also exhibited a high selectivity to Pb²⁺ over other metal ions such as Mg²⁺, Fe³⁺, Zn²⁺, Ca²⁺, and Cd²⁺.

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