Did you know that DNA molecules unfold when heated? Scientists at the University of Montreal do, and they used that knowledge to design a thermometer made of DNA. It’s totally invisible to the naked eye, though, so it can be a bit difficult to read.

Senior author of the paper “Programmable, quantitative, DNA Nanothermometers,” published in Nano Letters, Professor Alexis Vallée-Bélisle said, “Inspired by natural nanothermometers, which are typically 20,000x smaller than a human hair, we have created various DNA structures that can fold and unfold at specifically defined temperatures.”

DNA is relatively easy to program, according to the scientists behind the project. There are four different nucleotides that bind differently to each other: the bond between A and T is weak, while C and G’s is strong. David Gareau, first author of the study, explained that “using simple design rules we are able to create DNA structures that fold and unfold at a specifically desired temperature.”

A DNA-size thermometer means temperature can be measured at a nanoscale. Co-author Arnaud Desrosiers said, “By adding optical reporters to these DNA structures, we can therefore create 5 nm-wide thermometers that produce an easily detectable signal as a function of temperature.”  By measuring the movement one can tell the temperature at a nanoscale.

Nanotechnology is a rapidly growing field, and a thermometer tiny enough to function at that level would allow for new avenues of research. Professor Vallée-Bélisle pointed out, “For example, we know that the temperature inside the human body is maintained at 37° C, but we have no idea whether there is a large temperature variation at the nanoscale inside each individual cell.”

The implications for this technology stretch across many disciplines, into biology and beyond. The team is currently researching natural nanomotors to see if they overheat when functioning at high rates. Prof. Vallée-Bélisle predicts these working with electronics, saying “In the near future, we also envision that these DNA-based nanothermometers may be implemented in electronic-based devices in order to monitor local temperature variation at the nanoscale.”