Triptycene-Based Lipid Mimics for Thermally Stable Membrane Phase Separation

Area of Science:

• Materials Science
• Biochemistry
• Physical Chemistry

Background:

• Membrane phase separation creates distinct domains in lipid bilayers, offering potential for functional materials.
• Inducing thermally stable domains in fluid lipid bilayers is challenging due to high lipid miscibility.

Purpose of the Study:

• To design and synthesize triptycene-based lipid mimics for inducing thermally stable membrane phase separation.
• To investigate the mechanism of domain stabilization and explore applications in functional membrane materials.

Main Methods:

• Synthesis of amphiphilic triptycene derivatives using triple cycloaddition.
• X-ray diffraction, calorimetry, and fluorescence spectroscopy to analyze lipid bilayer behavior.
• Monolayer measurements to study the interaction between triptycene mimics and lipid molecules.

Main Results:

• Trialkyl-substituted triptycene (lipid mimic C) induced phase separation in dimyristoylphosphatidylcholine (DMPC) bilayers, forming C-rich domains.
• C-rich domains (2:1 DMPC:C) maintained gel-phase-like lipid packing at 30 °C and showed thermal stability up to 58 °C.
• DMPC/C bilayers exhibited rare fluid/fluid phase separation around 50 °C, stabilized by a dual embedding mechanism of triptycene units and lipids.

Conclusions:

• Triptycene-based lipid mimics provide a design principle for creating thermally stable artificial membrane domains.
• These domains offer a platform for compartmentalized membrane materials that leverage molecular clustering effects.
• The dual embedding mechanism involving triptycene interdigitation and lipid incorporation stabilizes the domains.