A new class of nanostructured plasmonic chemical sensors has been developed in recent years. Gold and silver nanoparticles are frequently studied because they exhibit a stong surface plasmon resonace in visible wave length. The aggregation of these nanoparticles will result in a significant color change that serves as the basis of sensitive chemical detection.

For example, the surface of Au nanoparticles may be derivatized with oligonucleotide and in the presence of complementary target DNA, Au nanoparticles will aggregate and change their approach was applied to trinitrotol-particles prepared from trisodium citrate were first treated with cysteamine. Upon addition of solution turned from red to violet blue owing to TNT-induced Au nanoparticle aggregation. Although these chemical sensing techniques were demonstrated in solution,it is likely that solid-state thin-film methods will be developed in the future.