A Colorimetric Selective Sensing Probe for Calcium Ions with Tunable Dynamic Ranges Using Glutathione Modified Gold Nanoparticles

We have obtained a kind of simple and highly effective method for detection of calcium ions based on glutathione functionalized gold nanoparticles (GSH-GNPs) in this article. The GSH-GNPs can be induced to aggregate immediately in the presence of calcium ions that can be detected by colorimetric response of GNPs monitored by a UV–vis spectrophotometer or even naked eyes, and the detection limit could reach 20 μM. Compared to other metal ions, the GSH-GNPs bound by calcium ions shows higher sensitivity with prominent color changes. Most importantly, the probe not only can be tested the content of calcium ion in the water simply and effectively, but also can be applied to estimate calcium levels in blood with low interference and high sensitivity.