Ultra-sensitive in situ detection of silver ions using a quartz crystal microbalance†
The detection of toxic nanomaterials is highly important, because their scientific and engineering applications have rapidly increased recently. Consequently, they can harmfully impact human health and the environment. Herein, we report a quartz crystal microbalance (QCM)-based, in situ and real-time detection of toxic silver ions by measuring a frequency shift. Generally, silver ions are so small that they are difficult to be identified using conventional microscopy. However, using QCM and a label-free silver-specific cytosine DNA, ultra-sensitive and in situ detection of silver ions is performed. The limit of detection (LOD) of this sensor platform is 100 pM, which is ten times lower than the previous study using a cantilever. It also detects silver ions rapidly in real time, which is completed within 10 min. Furthermore, our proposed detection method is able to detect silver ions in drinking water. The results suggest that QCM-based detection opens a new avenue for the development of a practical water testing sensor.