The challenge of intracellular temperature

Abstract

This short review begins with a brief introductory summary of luminescence nanothermometry. Current applications of luminescence nanothermometry are introduced in biological contexts. Then, theoretical bases of the "temperature" that luminescence nanothermometry determines are discussed. This argument is followed by the 10 5 gap issue between simple calculation and the measurements reported in literatures. The gap issue is challenged by recent literatures reporting single-cell thermometry using non-luminescent probes, as well as a report that determines the thermal conductivity of a single lipid bilayer using luminescence nanothermometry. In the end, we argue if we can be optimistic about the solution of the 10 5 gap issue.

In situ measurement of intracellular thermal conductivity using heater-thermometer hybrid diamond nanosensor

“…A transient value of ∆ in a region of radius requires heat energy ≈ 4∆^, where is the volumetric heat capacity. This temperature rise will last for a time interval ≈ @ / [24]. In the case 2 = 1 µm, ∆ = 1 K, = 4 MJ m 7^K78 , and = 0.07 W m 78 K 78 , the required energy is 2 pJ, about 10 7L times the energy of the glucose typically accumulated in a cell 19 while the corresponding ≈ 15 µs.…”

“…These reports have prompted active discussions about the origin and the biological significance of the heterogeneity. However, the results have also sparked hot debates about the validity of the temperature measurements [19][20][21][22][23][24] . The issue is that the temperature rise calculated by theoretical models describing physics of cellular thermogenesis and intracellular space is several orders of magnitude smaller than the experimental values reported in the literature.…”

“…However, Bastos et al have used upconverting nanoparticles 25 to measure the thermal conductivity of a single lipid bilayer and reported a value of 0.2 Wm -1 K -1 . Theoretically, the thermal conductivity in cells can be about six times smaller than that in water when the boundary heat resistance, or Kapitza resistance is considered 24 . Although it is pivotal to obtain the thermal conductivity in living cells and assess its variation at nanoscale experimentally, no such information is available to the best of our knowledge.…”

Metabolic Heat in Microbial Conflict and Cooperation

“…Many articles consider whether temperature gradients can be maintained within single cells 34,35 . The current consensus suggests that significant intracellular gradients are unlikely because heat diffuses too quickly within cells and across membranes 36,37 .…”

Metabolic Heat in Microbial Conflict and Cooperation

“…Many articles consider whether temperature gradients can be maintained within single cells (Inada et al, 2019;Suzuki and Plakhotnik, 2020). The current consensus suggests that significant intracellular gradients are unlikely because heat diffuses too quickly within cells and across membranes (Balaban, 2020;Oyama et al, 2020).…”