Developing molecules, switches, probes or nanomaterials that are able to respond to specific temperature changes should prove of utility for several applications in nanotechnology. Here, we describe bioinspired strategies to design DNA thermoswitches with programmable linear response ranges that can provide either a precise ultrasensitive response over a desired, small temperature interval (±0.05 °C) or an extended linear response over a wide temperature range (e.g., from 25 to 90 °C). Using structural modifications or inexpensive DNA stabilizers, we show that we can tune the transition midpoints of DNA thermometers from 30 to 85 °C. Using multimeric switch architectures, we are able to create ultrasensitive thermometers that display large quantitative fluorescence gains within small temperature variation (e.g., > 700% over 10 °C). Using a combination of thermoswitches of different stabilities or a mix of stabilizers of various strengths, we can create extended thermometers that respond linearly up to 50 °C in temperature range. Here, we demonstrate the reversibility, robustness, and efficiency of these programmable DNA thermometers by monitoring temperature change inside individual wells during polymerase chain reactions. We discuss the potential applications of these programmable DNA thermoswitches in various nanotechnology fields including cell imaging, nanofluidics, nanomedecine, nanoelectronics, nanomaterial, and synthetic biology.
MontrealU researchers have created a programmable DNA thermometer 20,000x smaller than a human hair. This may significantly aid our understanding of natural and human designed nanotechnologies by enabling to measure temperature at the nanoscale. Over 60 years ago, researchers discovered DNA molecules can unfold when heated. “In recent years, biochemists also discovered that biomolecules such as proteins or RNA are employed as nanothermometers in living organisms and report temperature variation by folding or unfolding,” says Prof. Alexis Vallée-Bélisle. “Inspired by those natural nanothermometers…we have created various DNA structures that can fold and unfold at specifically defined temperatures.”
One of the main advantages of using DNA to engineer molecular thermometers is that DNA chemistry is relatively simple and programmable. “DNA is made from four different monomer molecules called nucleotides: nucleotide A binds weakly to nucleotide T, whereas nucleotide C binds strongly to nucleotide G,” explains David Gareau. “Using these simple design rules we are able to create DNA structures that fold and unfold at a specifically desired temperature.” “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,” adds Arnaud Desrosiers.
These nanoscale thermometers open many exciting avenues in the emerging field of nanotechnology, and may even help us to better understand molecular biology. “There are still many unanswered questions in biology,” adds Prof. 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.” One question currently under investigation by the research team is to determine whether nanomachines and nanomotors developed by nature over millions years of evolution also overheat when functioning at high rate. “In the near future, we also envision that these DNA-based nanothermometers may be implement in electronic-based devices in order to monitor local temperature variation at the nanoscale,” concludes Prof. Vallée-Bélisle. http://www.eurekalert.org/pub_releases/2016-04/uom-cud042616.php
http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.6b00156
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