Colorimetric Detection of Pb2+ Based on G-Quartet Structure by Nanoprobes

A simple and sensitive detection method for lead ions was developed, based on the G-quartet and nanoprobe. The nanoprobe was prepared by modification of gold nanoparticles with G-rich oligonucleotides in a self-assembled way. In the presence of Pb2+, G-quartets are formed by G-rich oligonucleotides on the nanoprobes and result in the aggregation of nanoprobes and a change in color. Under the optimal condition of 200 mmol/L NaCl, 2.0 mmol/L MgCl2 and at 37 degrees C, the linear range was 48-480 nmol/L with a detection limit of 20 nmol/L for Pb2+. Most metal ions have no interferences, and the interfering Hg2+ can be effectively eliminated by a specific oligonucleotide. This method was applied for the detection of Pb2+ in environmental water samples, with a good reproducibility(RSD < 3.0%) and recovery(98.4%-101.5%).