Catalyst-Free One-Step Preparation of Self-Crosslinked pH-Responsive Vesicles

Area of Science:

• Polymer Chemistry
• Materials Science
• Nanotechnology

Background:

• Fabricating block copolymer (BCP) vesicles with controlled membrane permeability and stability is challenging.
• Existing methods often lack pH-responsiveness or require catalysts for cross-linking.

Purpose of the Study:

• To report a new type of pH-responsive and self-crosslinked vesicle.
• To demonstrate the vesicle's potential as a smart platform for drug delivery and molecular reactors.

Main Methods:

• Synthesis of a pH-responsive and hydrolytically self-crosslinkable copolymer (PEG-b-P(TBEU-co-DEA)) using reversible addition-fragmentation chain transfer (RAFT) polymerization.
• Self-assembly of the copolymer into vesicles driven by hydrophobic interactions and in situ cross-linking.
• Dynamic light scattering (DLS) to assess vesicle stability and pH-dependent size control.

Main Results:

• The copolymer self-assembled into stable vesicles through hydrolysis of hindered urea bonds without a catalyst.
• Vesicles demonstrated enhanced stability against organic solvent dilution and tunable size with pH.
• Alkaline phosphatase-loaded vesicles functioned as nano-reactors, enhancing fluorescence intensity.

Conclusions:

• The developed self-crosslinking, pH-sensitive vesicles offer a promising platform for controlled drug delivery.
• These vesicles can serve as efficient molecular reactors due to their controlled permeability.
• The hindered urea bond strategy provides a catalyst-free approach for vesicle fabrication.