Engineering Degradation Rate of Polyphosphazene-Based Layer-by-Layer Polymer Coatings

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Degradable layer-by-layer (LbL) polymeric coatings offer advantages in precision, bioactivity, and conformality for biomedical devices.
• Controlling degradation rates while maintaining biocompatibility in these coatings remains a significant challenge.

Purpose of the Study:

• To investigate polyphosphazenes as a tunable material for LbL coatings with controlled degradation.
• To compare the degradation behavior of polyphosphazenes in solution versus solid-state LbL films.
• To demonstrate methods for tuning the degradation rate of polyphosphazene-based LbL coatings.

Main Methods:

• Utilized pyrrolidone-functionalized polyphosphazenes for LbL film assembly with tannic acid.
• Monitored degradation rates in solution, complexes, and LbL coatings under varying pH conditions.
• Investigated the impact of film assembly conditions (e.g., pH, ionization) and chemical modifications (e.g., carboxylic acid moiety) on degradation.

Main Results:

• Degradation rate of polyphosphazenes accelerated under acidic conditions across all tested states.
• Tunable degradation rates were achieved in polyphosphazene-based LbL films by altering assembly conditions, such as increasing tannic acid ionization.
• Replacing pyrrolidone side groups with carboxylic acid moieties significantly reduced LbL coating degradation rates.

Conclusions:

• Polyphosphazenes are promising candidates for biocompatible LbL coatings with tunable degradation.
• Understanding degradation mechanisms in both solution and solid-state LbL films is crucial for material design.
• These tunable coatings offer versatile platforms for biomedical applications and controlled drug delivery systems.