Measuring the temperatures of the cell using Nano-thermometer
New research conducted at Rice University by a chemist, Angel Martí provides a new possibility to take the temperature inside the cell with the help of fluorescent Nano-thermometer.
The above research was published in the Journal of Physical Chemistry B paper, revealing the light-emitting property of a particular molecule, which was used to create Nano-thermometer, where a modified biocompatible molecular rotor known as Boron Dipyrromethane (i.e. BODIPY) was used to reveal the temperatures inside the cell.
Fluorescence of these molecules last only a little while inside the cells, and the duration depends on changes in both temperature and viscosity of its environment. At a specific temperature, the light turns off at a particular rate, that can be detected using a fluorescence- lifetime imaging microscopy.
Martí said, “Everybody knows old thermometer is based on the expansion of mercury, and newer once based on digital technology. But using those would be like trying to measure the temperature of a person with a thermometer the size of the Empire State Building.”
The technique depends upon the rotor. The rotor was constrained to go back and forth, like the flywheel in a watch, rather than letting it rotate fully.
“What we measure is how long the molecule stays in the excited state, which depends on how fast it wobbles,” he said. “If you can increase the temperature, it wobbles faster, and that shortens the time it stays excited.”
Since this technique takes advantage of the fluorescent properties of a modified molecular rotor and viscosity of the cell, it is conveniently independent of the concentration of BODIPY molecules in the cells and of the photobleaching molecules, where there is a photochemical alteration of fluorophore molecule such that it permanently is unable to produce fluorescence.
“If the environment is a bit more viscous, the molecule will rotate slower,” Martí said, “That doesn’t necessarily mean it’s colder or hotter, just that the viscosity of the environment is different.”
“We found out that if we constrain the rotation of a motor, then at high viscosities, the internal clock- the lifetime of this molecule- becomes completely independent of the viscosity,” he said. “This is not particularly common for these kind of probes.”
This technique is useful to detect the presence of cancer cells, by quantifying the effect of tumour ablation therapy, where cancer cells are detected by heat.
“They have a higher metabolism than other cells, which means they’re likely to generate more heat,” he said. “We’d like to know if we can identify cancer cells by the heat they produce and then differentiate them from normal cells.”