Highly sensitive label-free colorimetric sensing of nitrite based on etching of gold nanorods.

A simple colorimetric method with high sensitivity and selectivity was developed for sensing of nitrite as low as 4.0 µM by naked eyes, which is based on etching of gold nanorods accompanied by shape changes in aspect ratios (length/width) and a visible color change from bluish green to red and then to colorless with the increase of nitrite.