Polymalic Acid Tritryptophan Copolymer Interacts with Lipid Membrane Resulting in Membrane Solubilization

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Cell Biology

Background:

• Anionic polymers are crucial for cytoplasmic drug delivery.
• Existing polymalic acid (PMLA) copolymers use distinct membrane permeation mechanisms.
• Novel mechanisms are needed for enhanced drug delivery.

Purpose of the Study:

• To develop a novel anionic copolymer for enhanced membrane permeation.
• To elucidate the unique mechanism of membrane interaction for the new copolymer.
• To explore potential applications in targeted drug delivery.

Main Methods:

• Synthesis of tritryptophan-containing PMLA copolymer (P/WWW).
• Investigation of membrane permeation using size-exclusion chromatography, confocal microscopy, and fluorescence energy transfer.
• Analysis of copolymer-membrane interactions.

Main Results:

• P/WWW exhibits a novel "belt" mechanism for membrane permeation, distinct from "barrel stave" (P/LLL) and "carpet" (P/LOEt) mechanisms.
• Copolymer forms "belts" around planar membrane "packages," solubilizing membranes.
• Mechanism involves hydrophobic tryptophan side chains inserting into the lipid bilayer, dependent on membrane fluidity.

Conclusions:

• The "belt" mechanism offers a new paradigm for polymer-based membrane permeation.
• P/WWW shows potential for targeted delivery to abnormal cells with increased membrane fluidity.
• This mechanism may be responsive to conditions like hyperthermia.