Polyelectrolyte-coated liposomes: stabilization of the interfacial complexes.

Area of Science:

• Biophysical Chemistry
• Materials Science
• Nanotechnology

Background:

• Anionic liposomes are key components in drug delivery and biomaterials.
• Cationic polymers are utilized for surface modification and complex formation with anionic structures.
• Understanding polymer-liposome interactions is crucial for developing advanced nanocarriers.

Purpose of the Study:

• To investigate the binding interactions between anionic liposomes and cationic polymers.
• To identify factors influencing the stability and strength of polymer-liposome complexes.
• To explore the potential for constructing polyelectrolyte multilayers on liposomes.

Main Methods:

• Utilized anionic liposomes composed of egg lecithin (EL) or dipalmitoylphosphatidylcholine (DPPC) with cardiolipin (CL(2-)).
• Employed cationic polymers: fully quaternized poly(4-vinylpyridine) (P2) and poly-L-lysine (PL).
• Analyzed polymer/liposome binding using electrophoretic mobility (EPM), fluorescence, and conductometry, with variations in salt concentration and polyacrylic acid (PAA) presence.

Main Results:

• Electrostatic binding was observed between polymers (P2, PL) and small liposomes (EL/CL(2-), 60-80 nm), reversible by salt or PAA.
• Polymer hydrophobization (cetyl groups) enhanced binding.
• Binding increased with lipid bilayer solidification (DPPC vs. EL) and larger liposome size (300 nm vs. 60-80 nm).

Conclusions:

• Polymer-liposome binding is primarily electrostatic and influenced by lipid phase state, liposome size, and polymer modifications.
• Small, liquid, anionic liposomes coated with polycations bearing alkyl groups show promise for building stable polyelectrolyte multilayers without compromising liposome integrity.