DNA Used to Build the World's Smallest Thermometer

world's smallest thermometer DNA nanothermometer
Researchers from the University of Montreal were able to create a microscopic thermometer using strands of DNA. It will be used to monitor what happens inside the human body at a cellular level. REUTERS/Kai Pfaffenbach

A thermometer 20,000-times smaller than a human hair has been developed by researchers using DNA that is capable of measuring temperatures within living cells.

The thermometer, unveiled this week in the journal Nano Letters, was built by scientists at the University of Montreal and is expected to improve human understanding of nanotechnologies.

DNA is made up of four different molecules: Nucleotide adenine (A), nucleotide thymine (T), nucleotide cytosine (C) and nucleotide guanine (G). Nucleotides A and T bind weakly together, whereas nucleotides C and G bind strongly together.

By creating DNA structures made up of nucleotide pairs in a certain order, the researchers were able to make tiny nanothermometers that would fold and unfold at specific temperatures.

"By adding optical reporters to these DNA structures, we can therefore create 5nm-wide thermometers that produce an easily detectable signal as a function of temperature," said Arnaud Desrosiers, co-author of the study.

The thermometer was inspired by a natural process found within cells, whereby RNA molecules are employed as nanothermometers in living organisms to report temperature variation by folding and unfolding.

The researchers hope to use the thermometer to more accurately measure what happens inside the human body at a cellular level.

"There are still many unanswered questions in biology," said senior author Alexis Vallée-Bélisle. "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.

"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 a the nanoscale."