Ultrasensitive detection of lead ion based on target induced assembly of DNAzyme modified gold nanoparticle and graphene oxide

•A novel colorimetric strategy for lead ion detection has been established.•The detection relies on DNAzyme functionalized gold nanoparticles.•Target-induced cleavage can mediate assembly of graphene oxide.•The method displays excellent performance for the detection of lead ion.

In this paper, we report a novel colorimetric strategy for the detection of small molecules by using Pb2+ ion as an example. In this strategy, DNAzyme duplex modified gold nanoparticles (GNPs) are designed to be unable to interact with graphene oxide (GO). However, in the presence of Pb2+, the substrate strand of the DNAzyme is cleaved at its cleavage site, resulting in the disassembly of the DNAzyme duplex modified GNPs into three parts, i.e., the 3′- and 5′-fragments of substrate strand and the DNAzyme strand modified GNPs. By taking advantage of the efficient cross-linking effect of ssDNA-GNPs to GO, colorimetric sensor for the detection of the metal ion can be fabricated with a detection limit of 100 pM, which is much lower than the previous reports. This colorimetric method has also been used for the determination of Pb2+ in the tap water of the local city and the water from a reservoir with satisfactory results, so it may have potential applications in the future.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide