Researchers develop rapid, easy, and highly sensitive arsenic test with gold nanoparticles

The scientists have attached special organic molecules ta the surfaces of gold nanoparticles .These molecules act like ligants for arsenic ,meaning that they form a
complex with it.Each arsenic ion can bind to three ligands, which allows it to link together
up to three gold particles . The higher the arsenic concentration in the sample, the more
strongly the gold particles clump together and the number of bigger aggregates increases.
The color of gold nanoparticles in a liquid depends on their size. Whereas the arsenic-free gold
nanoparticles appear red , arsenic-induced aggregation causes the color to change to blue