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.