Reliably measuring the temperature of the inside of cells has been difficult to accomplish, but now researchers at The Institute of Photonic Sciences in Catalonia, Spain have developed a method of using Green Fluorescent Protein (GFP) to do just that. GFP famously transformed bioscience research over the last few decades, providing a way of tagging cells and following their lifestyles.
The technique measures Fluorescence Polarization Anisotropy (FPA), a phenomenon whereby the light coming off a fluorophore varies depending on the angle with respect to polarization at which it is being viewed.
Via Nanowerk, Jon Donner, one of the lead researchers of the study, explains the technology:
“In general, a population of fluorophores illuminated by a linearly polarized light re-emits partially polarized fluorescence due to the random orientation of the molecular dipoles. When the temperature increases, the Brownian rotational motion of the fluorophores is accelerated. Hence, the molecules will rotate more during their fluorescence lifetime. The more the molecules rotate during their fluorescence lifetime, the more the re-emitted photons will lose the memory of the incident light polarization. Consequently, a temperature increase leads to a decrease of the degree of polarization (anisotropy) of the fluorescence. Using a suitable calibration, FPA leads to an absolute temperature measurement. This is one of the main advantages of this technique.”
Abstract in Nano Letters: Mapping Intracellular Temperature Using Green Fluorescent Protein
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