Simultaneous Monitoring of Temperature and Ca2+ Concentration Variation by Fluorescent Polymer during Intracellular Heat Production.

The relationship between calcium ion (Ca2+) concentration and temperature variation during the oxidative phosphorylation (OXPHOS) process has become an essential focus for exploration of signaling pathways and neurodegenerative disease. However, there have been limited reports of fluorescent probes for simultaneous Ca2+ detection and temperature sensing. Herein, a new water-soluble fluorescent probe that combines a thermoresponsive polymer, curcumin and Fluo-4 AM for intracelllar temperature and Ca2+ sensing is described. Furthermore, this fluorescent polymer was successfully applied for intracelluar temperature and Ca2+ gradient monitoring generated by exogenous heating in HeLa cells. It was discovered that within 10 min after the OXPHOS process was induced by an inhibitor, the temperature increased 0.5-1.0 °C and the Ca2+ level decreased by about 5.7 μM. These results confirmed that the fluorescent polymer enabled investigation of the relationship between intracelluar temperature and Ca2+-induced neurotransmitter release.