Sensing Temperature in Vitro and in Cells Using a BODIPY Molecular Probe

Area of Science:

• Chemical Biology
• Biomedical Engineering
• Materials Science

Background:

• Boron dipyrromethene (BODIPY) dyes are known molecular rotors sensitive to environmental factors like viscosity, polarity, and temperature.
• Developing precise and non-invasive methods for monitoring cellular temperature is crucial for understanding biological processes and disease states.

Purpose of the Study:

• To develop and characterize a novel polyethylene glycol-modified BODIPY (PEG-BODIPY) dye for accurate temperature sensing in vitro and in live cells.
• To investigate the dye's response to temperature and viscosity changes, and its utility in fluorescence lifetime imaging microscopy (FLIM).

Main Methods:

• Synthesis and characterization of a 1,3,5,7-tetramethyl-8-phenyl-BODIPY derivative functionalized with a polyethylene glycol (PEG) chain.
• Measurement of fluorescence lifetime changes in response to varying temperatures and viscosities.
• Live cell imaging experiments using PEG-BODIPY to assess cellular uptake, localization, toxicity, and temperature mapping via FLIM.

Main Results:

• The PEG-BODIPY dye exhibits temperature-dependent changes in fluorescence lifetime, primarily due to increased nonradiative decay at higher temperatures.
• The dye's fluorescence lifetime shows distinct dependencies on temperature and viscosity, enabling selective temperature monitoring at high viscosity.
• PEG-BODIPY efficiently stains live cells (excluding the nucleus) without significant toxicity, even at high concentrations (100 μM).
• FLIM successfully visualized intracellular temperature variations with sub-degree resolution.

Conclusions:

• The developed PEG-BODIPY molecular rotor is a promising tool for quantitative, non-invasive temperature mapping in biological systems.
• This probe facilitates real-time monitoring of cellular thermal dynamics, offering insights into heat dissipation mechanisms.
• PEG-BODIPY holds potential for applications in studying thermal effects of medical treatments like radiofrequency ablation and photodynamic therapy.