A novel droplet-based approach to study phase transformations in lyotropic liquid crystalline systems

Area of Science:

• Materials Science
• Soft Matter Physics
• Chemical Engineering

Background:

• Lyotropic liquid crystals (LLCs) are of interest for drug delivery due to their tunable properties.
• Studying LLC phase transformations, especially those induced by compositional changes, is challenging with bulk methods.
• Enzymatic modifications to lipid structures can alter LLC behavior, necessitating advanced study techniques.

Purpose of the Study:

• To develop a novel microfluidic approach for producing and studying LLCs.
• To investigate the spatio-temporal formation of structures in LLCs at the droplet scale.
• To enable the study of phase transformations induced by compositional changes, such as enzymatic alterations.

Main Methods:

• Utilized a microfluidic device to generate separate lipid and aqueous droplets emulsified in fluorocarbon oil.
• Employed a hybrid polydimethylsiloxane (PDMS) and glass microfluidic chip for controlled droplet coalescence.
• Integrated in-situ time-resolved synchrotron small-angle X-ray scattering (SAXS) and polarized light microscopy for structural analysis.

Main Results:

• Janus-like droplets with distinct lipid and aqueous portions were formed upon coalescence.
• Observed a progression of mesophases as the aqueous portion hydrated the lipid portion through a diffusion-limited interface.
• Demonstrated droplet-scale observation of phase transformation kinetics and identification of non-equilibrium phases.

Conclusions:

• Microfluidic production and coalescence of droplets offer a new platform for studying LLCs.
• This method facilitates the investigation of structure formation and phase behavior in response to compositional gradients.
• The approach is valuable for understanding non-equilibrium phases and kinetics in droplet-based lyotropic systems.