i-Motif-modulated fluorescence detection of silver(I) with an ultrahigh specificity

• Ag+ shows a high specificity for inducing i-motif formation.
• A cyanine dye was designed to recognize i-motif formation.
• A novel Ag+ sensor is designed.
• The sensor shows excellent performance in specificity, sensitivity, and real time response.
• Detection of the Ag+ level in freshwater system is proved.

A novel Ag+ sensor has been designed based on the mechanism that i-motif formation induced by Ag+ was sensitively recognized by a cyanine dye. The sensor exhibited an over 130–16,000 fold selectivity toward Ag+ than that toward other metal ions. This research not only provides a step forward toward the development of Ag+ detection but also represents a new application for i-motif DNA.

The scheme for sensing Ag+ based on DMSB recognizing motif formation and the molecular structure of DMSB.Figure optionsDownload as PowerPoint slide