Measurement of Intracellular Temperature by Fluorescent Polymeric Thermometers

Abstract

Hyperthermia is a method by which external heat is applied to eliminate or control the growth of tumor cells and tissue by causing a raise in their temperature. However, existing knowledge is largely based on the temperature of the extracellular environment and little is known about intracellular temperatures. Recently, the invention of multiple new fluorescent thermometers has enabled the measurement of intracellular temperatures at high spatial resolution, hence facilitating the discussion of cellular activity from a thermodynamic point of view. This review focuses on fluorescent thermometers among the technologies developed for measuring intracellular temperatures, specifically providing a detailed account of recent findings regarding fluorescent polymer thermometers (FPTs). FPTs are capable of highly precise temperature measurements, to the order of 0.1℃ in a single cell. They have been used to reveal that intracellular temperatures are not uniform; for instance, the temperature of the nucleus is found to be higher than that of other cell organelles. It is expected that progress in the development of intracellular temperature measurement techniques, including FPTs, will provide a better understanding of hyperthermia, thus making it a more versatile and effective treatment method.