Highly sensitive detection of silver ions using a silver-specific DNA based nano-porous micro-resonator

Silver nanomaterials (nano-Ag) have been widely developed in various industrial and academic research areas and their release to the environment has raised concerns. When silver is released to the environment, the major environmental issues are bioaccumulation of silver and oxidation of silver into silver ions. Since the biological toxicity of silver ions is widely reported, a detection tool for silver ions is required to prevent its toxic effects on the environment and potential human health problems. In this report, we propose a high-sensitivity detection method for silver ions using silver-specific DNA that is composed of poly cytosine bases, a nano-porous micro-resonator (NPMR) and cytosine molecules. The detection was based on the frequency shift of the NPMR upon the specific interaction of silver ions between silver-specific DNA on the NPMR and cytosine molecules. We were able to detect silver ions with the limit of detection (LOD) of 10 pM in distilled (DI) water and of 1 nM in drinking water, which is at least 50 times higher than previous reports. Furthermore, silver ion detection was verified by using X-ray photoelectron spectroscopy and our proposed method is able to detect silver ions selectively among other types of metal ions.