A Cytosine-rich DNA Decorated Gold Nanoparticles Surface Enhanced Raman-Scattering Platform for Sensitive and Selective Detection of Silver Ions

In this work, we developed a label-free, homogeneous surface-enhanced Raman-scattering (SERS) platform for the rapid, simple and sensitive detection of Ag+ by using the unmodified gold nanoparticles (AuNPs). It utilizes the different absorption properties of single-strand DNA (ssDNA) and double-strand DNA (dsDNA) on citrate-coated AuNPs and specific interactions between Ag+ and cytosine-cytosine pairs. In the presence of Ag+, the structure of ssDNA containing rich cytosine will form a duplex, resulting in the salt-induced aggregation of gold nanoparticles; the corresponding SERS signal transduction can be observed due to the plasmonic coupling of metallic nanoparticles. The assay possesses a superior signal-to-background ratio as high as similar to 35.8 with a detection limit of 15 nM. This approach is not only rapid and convenient in operation, but also shows excellent selectivity, which makes it possible to detect Ag+ in actual samples.