Intracellular Thermal Probing Using Aggregated Fluorescent Nanodiamonds

Area of Science:

• Biophysics
• Nanotechnology
• Cell Biology

Background:

• Intracellular thermometry is crucial for understanding cellular physiology.
• Measuring organelle-specific temperatures requires precise nanoprobe positioning, which is challenging.
• Existing methods face limitations in targeting and manipulating nanoprobes within cells.

Purpose of the Study:

• To develop a method for precise intracellular temperature measurement using fluorescent nanodiamonds (FNDs).
• To demonstrate the aggregation of FNDs into microspheres for enhanced signal and controlled positioning.
• To enable high-precision, flexible single-cell analysis through accurate subcellular thermometry.

Main Methods:

• Endocytosed fluorescent nanodiamonds (FNDs) were aggregated into microspheres using optical forces.
• A scanning optical tweezing system was employed for precise patterning and positioning of FND microspheres within living cells.
• Temperature was detected by measuring fluorescence spectra of the FND microspheres at different intracellular locations.

Main Results:

• FND microspheres exhibited a sevenfold intensity enhancement of 546-nm laser excitation due to aggregation and electromagnetic resonance.
• Precise positioning of FND microspheres within cells was achieved using optical tweezing.
• Intracellular temperatures at specific locations were successfully detected by analyzing the fluorescence spectra.

Conclusions:

• Optical forces can be used to construct and position FND-based nanoprobes intracellularly.
• This method offers a novel approach for high-precision intracellular thermometry.
• The technique holds potential for advanced, flexible single-cell analysis and organelle-specific temperature mapping.