Vortex fluidic regulated phospholipid equilibria involving liposomes down to sub-micelle size assemblies

Area of Science:

• Biophysics
• Materials Science
• Nanotechnology

Background:

• Conventional microfluidic platforms are used for liposome formation but face scalability challenges.
• Liposomes are phospholipid-based nanostructures with applications in drug delivery and biomimicry.

Purpose of the Study:

• To investigate the use of a vortex fluidic device (VFD) for scalable liposome production.
• To characterize the self-assembly of phospholipids and liposome formation under VFD conditions.
• To explore liposome behavior and stability under shear stress within the VFD.

Main Methods:

• Utilized a 45° tilted, rapidly rotating glass tube (VFD) with a hydrophobic inner surface for continuous flow processing.
• Employed a confined mode of operation for fluorophore labeling of pre-VFD liposomes.
• Conducted in situ small-angle neutron scattering (SANS) to analyze phospholipid assemblies.

Main Results:

• The VFD successfully produced liposomes with an average diameter of approximately 110 nm.
• Increased rotation speeds led to the co-existence of ~110 nm liposomes with smaller phospholipid assemblies (rafts, micelles).
• Equilibria between liposomes and smaller structures were observed, correlating with fluid flow regimes in the VFD.

Conclusions:

• The vortex fluidic device offers a high-yielding, high-throughput method for scalable liposome production.
• ~110 nm liposomes represent the most stable self-assembled structure for phospholipids under these conditions.
• The VFD is a versatile platform for liposome formation, modification, and mechanistic studies.