In situ measurements of intracellular thermal conductivity using heater-thermometer hybrid diamond nanosensors.

Sotoma, Shingo; Zhong, Chongxia; Kah, James Chen Yong; Yamashita, Hayato; Plakhotnik, Taras; Harada, Yoshie; Suzuki, Madoka · Sci Adv · 2021

basic_science · Level V

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Abstract

Understanding heat dissipation processes at nanoscale during cellular thermogenesis is essential to clarify the relationships between the heat and biological processes in cells and organisms. A key parameter determining the heat flux inside a cell is the local thermal conductivity, a factor poorly investigated both experimentally and theoretically. Here, using a nanoheater/nanothermometer hybrid made of a polydopamine encapsulating a fluorescent nanodiamond, we measured the intracellular thermal conductivities of HeLa and MCF-7 cells with a spatial resolution of about 200 nm. The mean values determined in these two cell lines are both 0.11 ± 0.04 W m<sup>-1</sup> K<sup>-1</sup>, which is significantly smaller than that of water. Bayesian analysis of the data suggests there is a variation of the thermal conductivity within a cell. These results make the biological impact of transient temperature spikes in a cell much more feasible, and suggest that cells may use heat flux for short-distance thermal signaling.