Constraining Polymers into β-Turns: Miscibility and Phase Segregation Effects in Lipid Monolayers

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Surface Science

Background:

• Model biomembranes and macromolecule interactions are crucial for designing functional membrane systems, including drug delivery vehicles.
• Understanding synthetic polymer behavior at interfaces informs biomaterial development.

Purpose of the Study:

• To investigate the interfacial behavior of amphiphilic β-turn mimetic polymer conjugates.
• To examine the interaction of these conjugates with lipid model membranes.

Main Methods:

• Synthesis of polymer conjugates with hydrophobic polyisobutylene (PIB) or helical poly(n-hexyl isocyanate) (PHIC).
• Langmuir-film techniques, epifluorescence microscopy, and Atomic Force Microscopy (AFM).
• Analysis of phase behavior in mixed lipid/polymer membranes (DPPC).

Main Results:

• Polymer conjugates significantly disturbed dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers.
• Distinct domain formation of polymer conjugates was observed at high surface pressures (π > 30 mN·m⁻¹).
• Polyisobutylene (PIB) was found to incorporate into lipid membranes, unlike the immiscible PHIC.

Conclusions:

• Amphiphilic polymer conjugates can profoundly alter the structure of model lipid membranes.
• The findings provide insights into the design of synthetic macromolecules for membrane-based applications.
• Surface pressure is a critical factor influencing polymer conjugate organization at the air-water interface.