Locusts with nanoparticles injected into their brains could be used as sniffing cyborg detectors for explosives or environmental contaminants.
Researchers have previously sought to utilise locusts’ powerful sense of smell by placing electrodes in their brains and recording the signals that occur when they sniff certain chemicals. However, the accuracy of these systems isn’t always reliable because each locust will have a slightly different electrode placement in its brain, so the recorded neural activity will also differ slightly each time and sometimes be insufficient to distinguish a smell.
Now, at Washington University in St. Louis, Missouri, and his colleagues have found a way to boost the accuracy of this technique, using nanoparticles that can be heated with beams of infrared light. Once injected into the locusts’ brains and illuminated with a laser, the nanoparticles amplify the neural activity in response to smells.
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This made it easier for the researchers to differentiate odours when they tested locusts on a set of common chemicals.
“When we have this photothermal [light and heat] effect going on with these particles, there is a significant increase in the neural activity that is occurring in response to an odour stimulus,” says Singamaneni. “That helps us to amplify the response associated with any given chemical stimulus, which helps us to better separate these chemicals.”
The nanoparticles are made from a protein core and a silicon shell. They can also have chemicals loaded onto the exterior that are released when they are exposed to light.
Singamaneni and his team loaded the nanoparticles with a neurotransmitter called octopamine, which has been linked to the “fight or flight” response in insects, and found that this improved smell discrimination even further.
It is an interesting technological demonstration and the effect could be deployed in other medical applications that require localised heating, says at the Max Planck Institute for Chemical Ecology in Jena, Germany. It would have been interesting to see whether the locusts’ smelling performance could be improved just by heating the room they were in, he says.
Singamaneni and his team hope that modifying the locusts’ neural activity in this way might one day lead to a fully functional cyborg smell detector, but they still need to demonstrate the system working in real time, which could take some time, he says.
Nature Nanotechnology
