Despite its small size, estrogen can have far-reaching effects on humans and other animals despite its small size; its connection to the female reproductive system allows scientists to use it to monitor human fertility as well as control the reproductive cycle of cows and sheeps. Now, researchers from the Victoria University of Wellington have developed a sensor that can detect minute levels of E2, one of the primary estrogen receptors, in liquids.

The unique sensor sends electronic signals when it senses estrogen, which it accomplishes by using aptamers - small snippets of DNA - to latch onto estrogen molecules.

"Aptamers are a potentially powerful tool for sensors because they are so versatile and selective," Natalie Plank, co-author of the study, said in a press release. 

Plank and her colleagues developed the aptamers through a process that is very similar to natural selection. They created a diverse starting population that consists of various different DNA or RNA nucleotide sequences and eventually narrowed them down to the ones that had the highest affinity for estrogen. These aptamers were then attached to the carbon nanotube thin film field effect transistor (CNT FET) on their estrogen sensors.

When short aptamers where used, Plank and her team noticed that the aptamers sent off electric signals, whereas longer aptamers did not. They believe that this is because when they place the buffer solution on top of the CNT FET, the voltage of their detector causes the buffer solution to create a bilayer above it, which is disrupted by estrogen and, in turn, disrupts the electric current in the device. However, longer aptamers are most likely held above the bilayer, which does not distrub the electric signal.

With further research and advancements, the tool could eventually be used to detect the estrogen in bodily fluids and waterways. The team hopes to expand the device into a more complex setup and may even test out its ability to detect other substances.

"It's a very versatile way to build a sensor," said Plank.

The study was published in the Journal of Vacuum Science & Technology B.