Simultaneous Monitoring of Intracellular Temperature and Norepinephrine Variation by Fluorescent Probes during Norepinephrine Reuptake

Abstract

A long-standing challenge has been the simultaneous sensing of intracellular temperature and norepinephrine (NE) variations to explore signaling pathways and depression pathogeny. Here, we designed a fluorescent probe using poly(N-isopropylacrylamide) and 1- [4-(7-nitrobenzo [1,2,5]for simultaneously measuring the temperature and NE with high selectivity. The fluorescence intensity of the PNIPAm−AANBD moiety exhibited a good response to temperature changes. The PHE moiety could selectively sense NE due to the naphthalic anhydride group in PHE, which formed naphthalimide upon bonding with the primary amino group of NE. The hydroxyl-terminated ligand recognized the phenolic hydroxyl group of NE through the formation of hydrogen bonds. Using the proposed fluorescent probe, variations in the intracellular temperature and NE during NE reuptake could be simultaneously measured. It was first discovered that with the inhibition of antidepressant drugs, the intracellular temperature increased by 1.2−2.1 °C, and the NE reuptake decreased by about 21.5 μM. The measured variations in intracellular temperature and NE during neurotransmitter reuptake can shed light on the underlying mechanism of neurotransmitter signaling pathways, which may facilitate the treatment of depression.

Nanothermometer with Temperature Induced Reversible Emission for Evaluation of Intracellular Thermal Dynamics

“…Thus, the thermal-responsive polymers provide a promising candidate for adjusting the microenvironment of organic fluorophores in situ through the stimulation of temperature. It amplifies the response of fluorophores to the variation of temperature and improves the sensitivity and accuracy for temperature sensing. − Therefore, the development of fluorescent polymeric nanothermometers provides an opportunity to monitor intracellular heat generation and transfer processes.…”

Response strategies and biological applications of organic fluorescent thermometry: cell- and mitochondrion-level detection

“…4). 60,61 All the probes exhibited notable alterations in uorescence intensity when subjected to cellular temperatures exceeding 32 °C. Therefore, the LCST of thermoresponsive polymers determines the applicable temperature range of the uorescent temperature probes.…”