Luminescent molecular thermometers for the ratiometric sensing of intracellular temperature

Recently, numerous luminescent molecular thermometers that exhibit temperature-dependent emission properties have been developed to measure the temperatures of tiny spaces. Intracellular temperature is the most interesting and exciting applications of luminescent molecular thermometers because this temperature is assumed to be correlated with all cell events, such as cell division, gene expression, enzyme reaction, metabolism, and pathogenesis. Among the various types of temperature-dependent emission parameters of luminescent molecular thermometers, the emission intensity ratio at two different wavelengths is suitable for accurate and accessible intracellular temperature measurements. In this review article, luminescent molecular thermometers that exhibit a temperature-dependent emission intensity ratio in living cells are summarized, and current progress in intracellular thermometry is outlined.