Polymer-Surfactant Driven Interactions and the Resultant Microstructure in Protein-Containing Liquid Crystal Droplets

Area of Science:

• Materials Science
• Biophysics
• Supramolecular Chemistry

Background:

• Integrating molecular liquid crystals (LCs) with proteins offers potential for optical biosensing.
• Hydrophobic LCs and hydrophilic proteins typically require chemical modification for intermixing.
• Polymeric surfactants (PS) can create core-shell systems for protein sequestration in LCs.

Purpose of the Study:

• To investigate the interactions between liquid crystals (LCs), proteins, and polymeric surfactants (PS).
• To understand the microstructure of hybrid protein-LC systems.
• To explore the potential of these systems in optical biosensing.

Main Methods:

• Isothermal titration calorimetry (ITC) to quantify binding interactions.
• Fluorescence microscopy and infrared-imaging spectroscopy for microstructural analysis.
• Small-angle X-ray scattering (SAXS) to study LC order.
• All-atomistic molecular dynamic (MD) simulations to model component interactions.

Main Results:

• Strong hydrophobic interactions between LCs and PS drive myoglobin-PS (Mb-PS) sequestration into LC microdroplets or bulk LC.
• Binding constants and enthalpy changes increased significantly (∼2.5x) upon protein-PS conjugation.
• LCs acted as a solvent for Mb-PS, and LC long-range order decreased (coherence length from 8.9 to 5.7 nm).
• MD simulations confirmed strong favorable interactions between PS and LCs (-144 kJ mol⁻¹ PS⁻¹).

Conclusions:

• Hydrophobic interactions are key drivers for forming protein-LC hybrid materials.
• Protein conjugation to PS enhances sequestration and alters LC microstructure.
• These findings provide fundamental insights for designing advanced LC-based biosensing materials.