Nasal mucus proteins help create accurate machine 'nose'

Odours can be complex: different forms of the same molecule of carvone, for instance, can smell like either spearmint or caraway. While the human nose can easily distinguish between these two smells, until now, machines haven’t been able to.

However, for the first time, academics have created a biosensor that can differentiate between smells that are mirror images of each other - so-called chiral molecules. This development will enable the creation of a new generation of biosensors that are highly sensitive. The researchers say these biosensors could have industrial uses such as determining when food has gone off or ‘smelling’ how much pollution is in the atmosphere.

The biosensor utilises an odorant binding protein. These proteins are found in the nasal mucus and work olfactory receptors, helping us to create our perception of smell.

The research team developed a method to manufacture these proteins in sufficient quantities to create biosensors. From there, they developed methods to change the way the proteins react so they can recognise different types of chemicals. Using a type of transistor incorporating these proteins, the scientists were able to measure the unique changes in current as the proteins reacted to odours, and then record them. The machine effectively ‘smells’ the odour and then sends a message that can then be decoded.

“It has been challenging to get machines to be able to differentiate between smells that are mirror images of each other, which was a real barrier to creating machines which are able to smell as well as, or better than, humans,” said Professor Krishna Persaud, a University of Manchester academic who is the lead author of the paper.

“Using the expertise of our colleagues at the University of Bari to couple these proteins to field effect transistors has allowed us to produce a new chemical sensor platform. Now we have done this it will allow much better sensors to be developed and these could have many uses in industry. We shall be able to create biosensors which are accurate enough to be able to tell when food has gone off, or even smell how much pollution is in the atmosphere.”

The research team’s findings have been published in the journal Nature Communications.