Open AccessIntracellular Heat Transfer and Thermal Property Revealed by Kilohertz Temperature Imaging with a Genetically Encoded Nanothermometer
Author(s) -
Kuo Chang Lu,
Tetsuichi Wazawa,
Joe Sakamoto,
Cong Quang Vu,
Masahiro Nakano,
Yasuhiro Kamei,
Takeharu Nagai
Publication year - 2022
Publication title -
nano letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.853
H-Index - 488
eISSN - 1530-6992
pISSN - 1530-6984
DOI - 10.1021/acs.nanolett.2c00608
Subject(s) - thermal diffusivity , intracellular , materials science , heat transfer , temporal resolution , thermal , biophysics , temperature measurement , biological system , kinetics , chemical physics , chemistry , thermodynamics , optics , physics , biology , biochemistry , quantum mechanics
Despite improved sensitivity of nanothermometers, direct observation of heat transport inside single cells has remained challenging for the lack of high-speed temperature imaging techniques. Here, we identified insufficient temperature resolution under short signal integration time and slow sensor kinetics as two major bottlenecks. To overcome the limitations, we developed B-gTEMP, a nanothermometer based on the tandem fusion of mNeonGreen and tdTomato fluorescent proteins. We visualized the propagation of heat inside intracellular space by tracking the temporal variation of local temperature at a time resolution of 155 μs and a temperature resolution 0.042 °C. By comparing the fast in situ temperature dynamics with computer-simulated heat diffusion, we estimated the thermal diffusivity of live HeLa cells. The present thermal diffusivity in cells was about 1/5.3 of that of water and much smaller than the values reported for bulk tissues, which may account for observations of heterogeneous intracellular temperature distributions.