Stimuli-responsive poly(hydroxyethyl methacrylate) hydrogels from carboxylic acid-functionalized crosslinkers

Area of Science:

• Polymer Chemistry
• Biomaterials Science
• Materials Engineering

Background:

• Hydrogel properties can be tailored by modifying crosslinker structures.
• Developing responsive hydrogels is crucial for advanced applications like controlled drug delivery.

Purpose of the Study:

• Synthesize novel carboxylic acid-functionalized dimethacrylate crosslinkers.
• Fabricate pH- and redox-responsive poly(2-hydroxyethyl methacrylate)-based hydrogels.
• Investigate the swelling, degradation, and drug release characteristics of these hydrogels.

Main Methods:

• Synthesis of two novel carboxylic acid-functionalized dimethacrylate crosslinkers.
• Copolymerization with 2-hydroxyethyl methacrylate (HEMA) using photopolymerization.
• Photo-differential scanning calorimetry to assess reactivity.
• Characterization of hydrogel swelling, pH, and redox-responsive behavior.
• Drug release studies using Rhodamine 6G and resorcinol.

Main Results:

• Crosslinker 2a exhibited higher reactivity than 1a in photopolymerization.
• Hydrogel swelling depended on crosslinker structure, crosslinking degree, pH, and CaCl2 concentration.
• Hydrogels demonstrated redox-responsive degradation upon exposure to 1,4-dithiothreitol (DTT).
• Controlled release of Rhodamine 6G was observed, primarily at acidic pH.
• Resorcinol release was significantly enhanced by DTT-induced degradation.

Conclusions:

• Novel crosslinkers facilitate the design of tunable pH- and redox-responsive hydrogels.
• These hydrogels show potential as matrices for controlled release applications.
• The materials are promising candidates for tissue repair and regeneration due to their responsive nature.