A pH- and ionic strength-responsive polypeptide hydrogel: synthesis, characterization, and preliminary protein...

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Hydrogel Engineering

Background:

• Developing advanced hydrogels with controlled properties is crucial for drug delivery and tissue engineering.
• pH-responsive materials offer unique opportunities for triggered release and dynamic structural changes.
• Synthetic polypeptides provide a versatile platform for creating functional biomaterials.

Purpose of the Study:

• To synthesize and characterize a novel polypeptide hydrogel based on poly(L-glutamic acid) (PLG) and poly(ethylene glycol) (PEG).
• To investigate the pH-responsive swelling behavior and its underlying mechanisms.
• To evaluate the hydrogel's potential for controlled drug release applications.

Main Methods:

• Synthesis of PLG-PEG hydrogel via crosslinking.
• Swelling studies across a range of pH values.
• Circular dichroism spectroscopy to analyze secondary structure changes.
• Lysozyme release experiments under varying pH conditions.

Main Results:

• The PLG-PEG hydrogel exhibited significant pH-dependent swelling, increasing with higher PLG ionization.
• Secondary structural changes in the polypeptide backbone influenced the swelling response.
• Hydrogel modification allowed for tuning of pH-responsive swelling.
• Reversible swelling and de-swelling cycles were demonstrated.
• Rapid de-swelling effectively facilitated lysozyme release.

Conclusions:

• PLG-PEG hydrogels are highly tunable, pH-responsive, and biodegradable materials.
• The interplay of electrostatic effects and polypeptide secondary structure governs hydrogel swelling.
• This versatile approach enables the development of advanced drug delivery systems.