Researchers at the University of Montreal have engineered the world’s tiniest programmable thermometer, and used DNA to do so.
The miniscule thermometer is about 20,000 times thinner than a human hair, and works on the basis that DNA molecules unfold when heated to a certain temperature.
There is a need for nanoscale thermometers, which are used to aid in the development of the rapidly burgeoning field of nanotechnologies. Work on nanotechnologies today promise to do everything from detecting breast cancer to building better electronics.
Small thermometers are used to monitor the temperature fluctuations within these small structures because normal tools are too big for these nano-scale devices.
"In recent years, biochemists also discovered that biomolecules such as proteins or RNA (a molecule similar to DNA) are employed as nanothermometers in living organisms and report temperature variation by folding or unfolding," said one of the team, Alexis Vallée-Bélisle.
The researchers took that inspipration, and created various DNA structures that can fold and unfold at specifically defined temperatures, helping users determine the temperature in nano-scale structures.
With DNA consisting of four nucleotides (A, T, C, and G), the team could design a mechanism that would force the molecule to fold or unfold at a given temperature, signalling to the observer what temperature the molecule, and by extension, its environment, had reached.
Using structural modifications or inexpensive DNA stabilisers, the researchers could tune the DNA thermometers to fold and unfold at a range of temperatures from 30 to 85°C.
They were also able to use multimeric switch architectures to create ultrasensitive thermometers that display large quantitative fluorescence gains within small temperature variation.
By combining different thermoswitches with different stabilities, or a mix of stabilizers of various strengths, the researchers created extended thermometers that respond linearly up to 50°C in temperature range.
To make them easier to read, the researchers added optical reporters to the DNA structures, resulting in the final thermometers, which are 5 nm wide, and produce an easily detectable signal as a function of temperature.
Besides helping with process monitoring and management of nano-scale devices, these thermometers will also help answer a number of questions ,such as whether the human body runs hotter than 37°C on the nanoscale, or if naturally occurring nanomachines overheat when functioning at high rate.
[Image credit: Andy Eick @ Flickr]
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