London, Apr 23 : US researchers have developed a set of gold nanoparticles with various coatings which can identify proteins by mimicking the way the human nose distinguishes scents.

The scientists are presently using them to detect signs of illness in bodily fluids.

“In your nose there are a variety of receptors that all react in slightly different ways to compounds,” said Vince Rotello from the University of Massachusetts, US.

Instead of having a specific sensor for each smell, the nose responds to the pattern of responses produced by multiple, generalised receptors. With colleagues from his own university and Georgia Institute of Technology, also in the US, Rotello applied the same principle to detect proteins.

Although electronic noses have been developed before, this is the first system capable of identifying larger and more complicated molecules.

The new “nano nose” has six receptors, each consisting of a solution containing gold nanoparticles, with different coatings, measuring two nanometres across.

The coatings are made from slightly different organic molecules containing nitrogen atoms.

According to the research team, different proteins will bind to multiple receptors but will attach more easily to some than others.

The team measured the binding properties using a fluorescent signal molecule that attached to the receptor particles but was displaced by a protein when it bound.

They found that the more this molecule was displaced, the more light it produced.

A computer then analyses the relative strengths of these light signals.

Rotello and his colleagues used blind experiments with 56 random proteins to show that the pattern of signals produced by the receptors could collectively be used to tell proteins apart.

In the tests the device was found to be 96 percent accurate.

Rotello believes the system could be useful for detecting diseases. Instead of looking for a single specific marker molecule, it would sniff out an imbalance in the usual combination of proteins in body fluids.

Early results, with blood plasma from sick and healthy lab animals, have been promising.

“We want this nose to be able to say, ‘I smell something funny’. We can detect changes in serum and are working on making that ability statistically robust. Later we can start working out which ’smells’ point to particular kinds of cancer or other diseases,” New Scientist quoted him as saying.

The findings appear in the journal Nature Nanotechnology. (ANI)