A colorimetric lead (II) ions sensor based on selective recognition of G-quadruplexes by a clip-like cyanine dye

• A probe is designed for colorimetric detection of Pb2+.
• A clip-like cyanine dye is synthesized.
• The dye can recognize Pb2+-induced G-quadruplex transition.
• The probe shows a high specificity and sensitivity.
• Detection of the Pb2+ in freshwater system is applied.

A probe for colorimetric detecting lead ion (Pb2+) has been designed by using a newly synthesized clip-like cyanine dye and G-quadruplex. The unique structure of the clip-like cyanine dye endowed the probe with a high selectivity towards Pb2+. Significant changes in absorption spectra of the cyanine dye recognizing the Pb2+-induced conformational transition of G-quadruplexes made the probe show a high sensitivity towards Pb2+ with a detection limit of 1 nM. The excellent performance enabled the probe to be practically applied in measuring the Pb2+ pollution in freshwater system.

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