Page 5 - SensNews Apr13

Rapid, Sensitive Nano-Technology to Detect

Hazardous Chemicals

Scientists at the

Department of Chemistry, Imperial College

,

have developed an ultra sensitive, rapid approach to detecting haz-

ardous chemicals such as explosives, pollutants and illegal drugs.

The new system can pick out a single

target molecule from 10 000 trillion

water molecules within milliseconds,

by trapping it on a self-assembling sin-

gle layer of gold nanoparticles, formed

at the interface between two immis-

cible fluids such as air and water or

water and oil. The target molecules

are identified by an effect called Surface

Enhanced Raman Scattering (SERS) of

light in which each molecule scatters light in a unique way.

SERS has been in use since the 1970’s and previous work has

shown that the light signal can be amplified by catching the target

molecule on a gold nano-particle sheet. The IC chemists’ advance

is to find conditions that allow the gold particles to form at the

interface between two immiscible fluids. If the nanoparticles are

disturbed, they spontaneously arrange themselves back in the cor-

rect way make the device more robust than those made rigidly

arranged particles.

Research co-author, Michael Cecchini, said:“Our system could

solve a key problem of reliable and portable chemical testing for

use in the outside world. It is very sensitive and could well be used

to look for very small amounts of a specific molecule even in busy,

public areas.”