Capacious and programmable multi-liposomal carriers.

Area of Science:

• Biomaterials Science
• Nanotechnology
• Physical Chemistry

Background:

• Spherical polycationic brushes (SPBs) are synthesized by grafting polycationic chains onto polystyrene nanoparticles.
• Anionic liposomes, composed of egg-lecithin (EL) and phosphatidylserine (PS), are utilized for their specific membrane properties.

Purpose of the Study:

• To investigate the electrostatic complex formation between SPBs and anionic liposomes.
• To explore the pH-triggered release of liposomal contents upon complexation with SPBs.
• To determine the effect of a morpholinocyclohexanol-based lipid (MOCH) on liposome membrane stability and cargo release.

Main Methods:

• Synthesis of SPBs and preparation of anionic EL/PS liposomes.
• Complexation of SPBs with liposomes at pH 7.0 via electrostatic interactions.
• Induction of cargo release by decreasing pH from 7.0 to 5.0 and monitoring liposome membrane integrity.
• Comparative analysis of cargo release rates from complexed versus non-complexed liposomes.

Main Results:

• SPBs electrostatically complexed with approximately 40 anionic liposomes per SPB particle at pH 7.0.
• A pH decrease to 5.0 induced rapid cargo release from complexed liposomes due to MOCH-induced bilayer defects.
• The pH drop did not disrupt the SPB-liposome complex, and 50-60% of contents were released before membrane healing.
• Complexed liposomes exhibited significantly faster cargo release compared to non-complexed liposomes.

Conclusions:

• SPBs effectively complex with anionic liposomes, forming stable structures.
• The MOCH lipid facilitates pH-triggered membrane destabilization and rapid cargo release in complexed liposomes.
• This system demonstrates potential for controlled drug delivery applications, leveraging pH-responsive release mechanisms.