A Lead (II) Ion Sensor Based on Selective Recognition of G-quadruplex for Ethyl-substitutive Thioflavin T

ThT-E (ethyl-substitutive Thioflavin T), a derivative of Thioflavin T (ThT), is capable of inducing a guanine -rich nucleic acid sequence that forms a parallel G-quadruplex under certain conditions and exhibits significant fluorescence enhancement. In this work, we used Pb2+ to induce parallel G-quadruplex into anti-parallel G-quadruplex to reduce fluorescence of ThT-E and found a simple Pb2+ detection method. Through this approach, Pb2+ in aqueous solutions can be detected at 0. 76 nM with fluorescence spectrometry in a facile way, with high selectivity against other metal ions. These results indicate the method for detecting Pb2+ is simple, sensitive, specific and label-free.