Opto-mechanical coupling in interfaces under static and propagative conditions and its biological implications

Area of Science:

• Cell biology
• Biophysics
• Physical chemistry

Background:

• Fluorescent dyes are essential tools for visualizing cellular processes.
• Dye emission properties are sensitive to their local microenvironment.
• Understanding this sensitivity is key to accurate biological interpretation.

Purpose of the Study:

• To investigate the relationship between fluorescent dye intensity and the thermodynamic state of lipid interfaces.
• To quantify the opto-mechanical coupling in lipid-dye systems.
• To explore the applicability of this coupling under non-equilibrium conditions.

Main Methods:

• Embedding fluorescent dyes in lipid interfaces.
• Measuring fluorescence intensity as a function of lateral pressure (π) and temperature (T).
• Analyzing opto-mechanical coupling and constructing interfacial thermodynamic state diagrams.

Main Results:

• Fluorescence intensity was confirmed as a thermodynamic observable.
• State diagrams successfully quantified the coupling between intensity (I) and lateral pressure (π).
• Opto-mechanical coupling remained conserved across temperature variations and applied to dynamic pressure pulses.

Conclusions:

• Lipid membrane thermodynamic state variations (pressure, temperature, etc.) directly control fluorescence intensity.
• Fluorescence sensitivity is pronounced during dynamic state changes, like liquid-expanded to liquid-condensed phase transitions.
• Interfacial thermodynamic state diagrams are crucial for accurate interpretation of fluorescence intensity data.