Tailored nanoparticles known as nanoshells can enhance chemical sensing via Raman scattering by as much as 10 billion times, Rice University researchers have found.

The finding means that all-optical nanoscale sensors — essentially new molecular-level diagnostic instruments — could be designed that detect as little as a few molecules of a target substance, such as a drug molecule, disease protein, or deadly chemical agent.

Nanoshells are ball-shaped and consist of a core of non-conducting glass covered by a metallic shell, typically either gold or silver. The metal shell “captures” passing light and focuses it, a property that directly leads to the enormous enhancements observed.

Nanoshells can also be “tuned” to interact with specific wavelengths of light by varying the thickness of their shells. This tunability allows for the Raman enhancements to be optimized for specific wavelengths of light.

Rice University news release