The zinc effect by discovered by chance while researchers were investigating its ability to kill cancer cells. When they isolated the zinc nanoparticles and added them to tissue taken from the noses of rodents, the electrical activity tripled in the presence of an odor.
Setting out to exclusively study this phenomenon, the team put 14 dogs inside magnetic resonance imaging (fMRI) scanners. For some dogs, they gave them zinc nanoparticles along with an odor to smell. For the control dogs, they gave them the odor only. The smells included cloves, spearmint, and a fruit blend. The outcome confirmed the finding in the rodent experiment--the nanoparticles tripled activity in the dogs' brains (in areas related to smell) when they were given an odor.
According to lead scientist, Vitaly Vodyanoy, it appears that the nanoparticles increase the activity of sensory receptors. This enhancement lasts about ten seconds. After that short period of time, the next sniff of odor (without additional nanoparticles) produces a normal response.
Zinc also seems to work with people too. Vitaly tried it himself and felt it enhanced his sense of smell. They're now starting to work with a fragrance company to conduct tests on humans.
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But the dogs weren't just testing the nanoparticles for people. Another researcher on the study, Dr Gopikrishna Deshpande, said they hoped improving dogs' sense of smell would help working pups excel at their jobs. Gopikrishna explained that dogs can miss detection of explosives that are intentionally concealed to not give out odor.
As a next step, scientists will have to figure out how to make the effects last longer than ten seconds! However, the findings are a cool discovery that could potentially help sniffing dogs to be even better at their important work.