High-sensitivity detection of silver ions using oligonucleotide-immobilized oscillator.

With the remarkable developments in the fields of nanoscale research and industry, nanotoxicity is gaining importance from the viewpoint of its potential impact on human health and the environment. Herein, we report on the label-free, high-sensitivity detection of Ag(+), a representative nanotoxic material, by using a silver-specific nucleotide-coated oscillator. The detection is based on the measurement of the resonant frequency shift arising from constitution of the cytosine-Ag(+)-cytosine bonding. We amplify the resonant frequency shift by using single cytosine molecules. It is shown that a silver-specific DNA-immobilized oscillator enables the capture of silver ions at concentrations below 1 nM. Remarkably, the nucleotide-based oscillator enables an insight into the coordination chemistry, which plays an important role in the early detection of toxicity. This implies that the bio-conjugated sensor could be used to set the reference point for water quality.