A nanoparticle-based ratiometric and self-calibrated fluorescent thermometer for single living cells

Yoshiaki Takei, Satoshi Arai, Atsushi Murata, Masao Takabayashi, Kotaro Oyama, Shin'Ichi Ishiwata, Shinji Takeoka*, Madoka Suzuki

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

184 Citations (Scopus)


The homeostasis of body temperature and energy balance is one of the major principles in biology. Nanoscale thermometry of aqueous solutions is a challenging but crucial technique to understand the molecular basis of this essential process. Here, we developed a ratiometric nanothermometer (RNT) for intracellular temperature measurement in real time. Both the thermosensitive fluorophore, β-diketonate chelate europium(III) thenoyltrifluoroacetonate, and the thermoinsensitive fluorophore, rhodamine 101, which was used as a self-reference, are embedded in a polymeric particle that protects the fluorophores from intracellular conditions. The ratiometric measurement of single RNT spots is independent of the displacement of the RNT along the z-axis. The temperature is therefore determined at the location of each RNT under an optical microscope regardless of the dynamic movement of living cells. As a demonstration of the spot-by-spot intracellular thermometry, we successfully followed the temperature change in individual RNT spots in a single cell together with the Ca2+ burst induced by the Ca2+ ionophore ionomycin. The temperature increases differently among different spots, implying heterogeneous heat production in the cell. We then show that, in some spots, the temperature gradually decreases, while in others it remains high. The average temperature elevation within a cell is positively correlated to the increase in Ca2+, suggesting that the activity and/or number of heat sources are dependent on the Ca2+ concentration.

Original languageEnglish
Pages (from-to)198-206
Number of pages9
JournalACS Nano
Issue number1
Publication statusPublished - 2014 Jan 28


  • fluorescent nanoparticle
  • polymer nanoparticle
  • ratiometry
  • rhodamine 101
  • thermogenesis
  • thermometry

ASJC Scopus subject areas

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy


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