Fluorescence polarization sensor platform based on gold nanoparticles for the efficient detection of Ag (I)

Silver is one of the most important heavy metals with a broad range of applications; however, it can have significant negative impacts on both the ambient environment and organisms. For this work, an interesting fluorescence polarization sensor based on SH-DNA functionalized gold nanoparticles (AuNPs) was proposed for the detection of Ag+ in aqueous solutions. Moreover, this sensing strategy is quite simple, sensitive, selective, and cost-effective. Ag+ ions can interact specifically with a cytosine-cytosine (C-C) mismatch in DNA duplexes to form stable metal-mediated cytosine-Ag+-cytosine (C-Ag+-C) base pairs. The creation of these C-Ag+-C complexes results in evident changes in the molecular volume and fluorescence polarization signal. The stable hybridization between the two probes occurs with the formation of the C-Ag+-C complex in the presence of Ag+ ions, which leads to obvious fluorescence quenching in contrast to the system without AuNP. This assay may be employed to identify nanomolar levels of Ag+ within 6 min at room temperature. Furthermore, the sensor was successfully adopted to detect Ag+ ions in environmental water samples, which may facilitate the potential development of a range of environmental monitoring applications.