Highly sensitive and selective detection of Pb2+ using a turn-on fluorescent aptamer DNA silver nanoclusters sensor.

A novel turn-on fluorescent biosensor has been constructed using C-PS2.M-DNA-templated silver nanoclusters (Ag NCs) with an average diameter of about 1 nm. The proposed approach presents a low-toxic, simple, sensitive, and selective detection for Pb2+. The fluorescence intensity of C-PS2.M-DNA-Ag NCs enhances significantly in the presence of Pb2+, which is attributed to the special interaction between Pb2+ and its aptamer DNA PS2.M. Pb2+ induces the aptamer to form G-quadruplex and makes two darkish DNA/Ag NCs located at the 3' and 5' terminus close, resulting in the fluorescence light-up. Moreover, Pb2+ can be detected as low as 3.0 nM within a good linear range from 5 to 50 nM (R = 0.9862). Furthermore, the application for detection of Pb2+ in real water samples further demonstrates the reliability of the sensor. Thus, this sensor system shows a potential application for monitoring Pb2+ in environmental samples.