Extending the pH Stability of Poly(2-Oxazoline)/Poly(Acrylic Acid) Double-Network Hydrogels by Including Acrylamide...

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Tissue Engineering

Background:

• Double-network hydrogels (DNHs) offer excellent mechanical properties for biomedical uses like artificial cartilage.
• Existing poly(2-methyl-2-oxazoline) and poly(acrylic acid) DNHs mimic natural cartilage but deprotonate at pH 7.6, limiting use in environments with higher pH.
• Varying pH conditions in vivo necessitate hydrogels with enhanced stability at more basic pH levels.

Purpose of the Study:

• To enhance the pH stability of poly(2-methyl-2-oxazoline)-based double-network hydrogels.
• To investigate the effect of copolymerizing acrylic acid with acrylamide on hydrogel properties.
• To develop a DNH suitable for biomedical applications under a wider range of physiological pH conditions.

Main Methods:

• Systematic variation of the secondary network in poly(2-methyl-2-oxazoline)-based DNHs by copolymerizing acrylic acid (AA) and acrylamide (AAm).
• Mechanical property evaluation of the synthesized DNHs in phosphate-buffered saline (PBS) across a range of pH values.
• Characterization of hydrogel dimensional stability and mechanical behavior at elevated pH.

Main Results:

• A poly(2-methyl-2-oxazoline)/poly(acrylic acid-co-acrylamide) [PMOx/P(AA₉₀-co-AAm₁₀)] DNH was successfully synthesized with 10 wt.% acrylamide in the secondary network.
• This optimized DNH remained undeprotonated up to pH 9.
• The hydrogel maintained its dimensions and cartilage-like mechanical properties even at pH 9.

Conclusions:

• Copolymerization of acrylamide into the secondary network significantly enhances the pH stability of PMOx-based DNHs.
• The developed PMOx/P(AA₉₀-co-AAm₁₀) DNH exhibits remarkable stability and mechanical integrity at basic pH levels.
• This enhanced DNH holds significant promise for biomedical applications requiring stable mechanical performance in diverse physiological environments, including those with inflammation or infection.