Tunable and Selective Degradation of Amine-Reactive Multilayers in Acidic Media

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Developing stimuli-responsive materials is crucial for advanced applications.
• Existing degradable multilayers often lack tunable degradation profiles and post-fabrication modification capabilities.

Purpose of the Study:

• To design reactive and hydrolytically degradable multilayers using a novel covalent layer-by-layer assembly.
• To create materials with tunable degradation triggered by pH changes.
• To explore post-fabrication functionalization for tailored properties.

Main Methods:

• Covalent layer-by-layer assembly of poly(2-vinyl-4,4-dimethylazlactone) with acetal-containing diamine linkers.
• Fabrication of thin films and hollow capsules.
• Post-fabrication functionalization of residual azlactones with amines.
• In vitro studies of degradation, cargo release, and cellular uptake.

Main Results:

• Successfully synthesized cross-linked multilayers with residual azlactone reactivity and acid-labile acetal cross-links.
• Materials exhibited stability at pH 7.4 and gradual degradation in mildly acidic environments (pH 5).
• Degradation rates were tunable from hours to days via post-fabrication modification.
• Demonstrated acid-triggered release of encapsulated cargo from microcapsules.
• Cellular uptake and intracellular degradation of microcapsules were influenced by surface functionalization.

Conclusions:

• This approach provides a new, modular platform for stimuli-responsive nano/biointerfaces with transient stability.
• The introduction of acid degradability expands triggering stimuli to include biologically relevant pH changes.
• Post-fabrication modification offers a unique strategy for tuning degradation profiles in degradable multilayers.