A "turn-on" polymer nanothermometer based on aggregation induced emission for intracellular temperature sensing

Area of Science:

• Nanotechnology
• Biophysics
• Materials Science

Background:

• Accurate nanoscale temperature measurements are crucial for understanding cellular heat dynamics.
• Existing nanothermometers face challenges with intracellular microenvironment interference.
• Developing robust and sensitive nanothermometers is essential for biological research.

Purpose of the Study:

• To construct a novel fluorescent polymer nanothermometer (PNIPAM-TPPEBr) for precise intracellular temperature measurements.
• To investigate the thermo-responsive properties and sensing mechanism of the nanothermometer.
• To demonstrate the application of the nanothermometer in live cell temperature imaging.

Main Methods:

• Synthesis of a tetraphenylethylene-functionalized fluorophore (TPPEBr) with aggregation-induced emission (AIE) properties.
• Polymerization of TPPEBr with a thermo-responsive N-isopropylacrylamide (NIPAM) unit to form PNIPAM-TPPEBr.
• Characterization of the nanothermometer's fluorescence response to temperature changes and its application in A549 cell imaging.

Main Results:

• The PNIPAM-TPPEBr nanothermometer exhibits enhanced fluorescence with increasing temperature due to TPPEBr aggregation.
• A temperature-dependent blue shift in emission wavelength was observed, linked to microenvironment polarity changes.
• The nanothermometer demonstrated high thermo-responsiveness (up to 13.2 %°C⁻¹) in the physiological range and was successfully used for intracellular temperature imaging.

Conclusions:

• The PNIPAM-TPPEBr nanothermometer offers a reliable and sensitive method for nanoscale temperature sensing.
• Its performance is independent of the intracellular microenvironment, overcoming a key limitation of previous methods.
• This technology provides a valuable tool for studying cellular thermoregulation and heat-related physiological processes.