A novel AuNP colorimetric sensor based on a polyadenine probe for ultra-sensitive detection of Ag.

Silver(I) ions (Ag) are harmful to humans and can be bioaccumulated in organisms. Although numerous methods for Ag analysis have been established, new strategies are still in urgent need. Here, we propose a colorimetric sensor based on polyadenine (polyA)-mediated DNA-functionalized gold nanoparticles (AuNPs) for the specific measurement of Ag ions. In this strategy, a polyA-modified Au probe with high uniformity was assembled successfully. The method was based on Ag-induced aggregation of the probe. Ag was reflected according to the color variations of solution. Taking advantage of the low cost and convenient assembly of the polyA-based Au probe, our strategy determined Ag with high sensitivity and wide range. In addition, by changing probes or nanoparticles, the proposed strategy is expected to be a universal platform for detecting other analytes in environmental and even biological samples.