Graphene Quantum Dots as Intracellular Imaging-Based Temperature Sensors.

Area of Science:

• Nanotechnology
• Biophysics
• Materials Science

Background:

• Non-invasive temperature sensing is crucial for understanding cellular processes like enzyme activity and protein expression.
• Existing methods often lack the resolution or biocompatibility for sub-cellular analysis.

Purpose of the Study:

• To develop and evaluate novel graphene quantum dots (GQDs) as luminescence nanothermometers for non-invasive, sub-cellular temperature sensing.
• To investigate the temperature-dependent fluorescence properties of GQDs synthesized via top-down and bottom-up approaches.

Main Methods:

• Synthesis of graphene quantum dots (GQDs) using top-down (RGQDs) and bottom-up (N-GQDs) methods.
• Characterization of GQD fluorescence properties in aqueous suspension and within HeLa cells.
• In vitro testing of GQD nanothermometers across physiological temperature ranges (25-49 °C).

Main Results:

• Both RGQDs and N-GQDs exhibited temperature-sensitive, photostable fluorescence.
• Linear and reversible fluorescence quenching up to 19.3% was observed in aqueous GQD suspensions (25-49 °C).
• Internalized GQDs in HeLa cells showed enhanced quenching (>40%) within the 25-45 °C range.

Conclusions:

• Synthesized GQDs function as effective non-invasive nanothermometers for microscopic biological environments.
• The temperature-dependent fluorescence quenching mechanism is reversible and photostable, suitable for sub-cellular temperature monitoring.
• GQD-based nanothermometry holds promise for advancing the study of temperature-sensitive biological processes at the nanoscale.