Cationic-perylene-G-quadruplex complex based fluorescent biosensor for label-free detection of Pb2+

Publication date: 1 March 2016
Source:Talanta, Volume 149
Author(s): Xu-Hua Zhao, Liang Gong, Yuan Wu, Xiao-Bing Zhang, Jun Xie
In this work we use a water-soluble cationic perylene derivative (compound 1) as the G-quadruplex (G4) structure fluorescence indicator to construct a fluorescent biosensor for simple, rapid and label-free detection of Pb²⁺. In the absence of Pb²⁺, strong electrostatic interactions between compound 1 and the G-rich DNA probe (PW17) induced the aggregation of compound 1 and resulted in the fluorescence quenching. In the presence of Pb²⁺, the PW17 formed Pb²⁺-stabilized G4 structure, which reduced the aggregation of compound 1 and gave rise to high fluorescence. This allowed us to use convenient "mix-and-detect" protocol for quantitative analysis of Pb²⁺. Since Pb²⁺ can specially induce PW17 to form compact DNA fold, our proposed biosensor displayed high selectivity for Pb²⁺. It also exhibited a high sensitivity to Pb²⁺, with a limit of detection of 5.0nM observed. Furthermore, the biosensor was applied for the detection of Pb²⁺ in urine and paint samples, and both showed satisfactory results.

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