Enzymatically degradable temperature-sensitive polypeptide as a new in-situ gelling biomaterial

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Drug Delivery Systems

Background:

• Developing stimuli-responsive materials is crucial for advanced biomedical applications.
• Polymeric hydrogels offer versatile platforms for controlled release and tissue regeneration.
• Understanding polymer degradation and in-situ gelling mechanisms is key for therapeutic efficacy.

Purpose of the Study:

• To investigate the sol-to-gel transition of poly(ethylene glycol)-block-poly(alanine-co-phenyl alanine) (PEG-PAF) aqueous solutions.
• To elucidate the mechanism behind the temperature-induced gelation.
• To evaluate the degradation profile and in-vivo feasibility of PEG-PAF as a drug delivery system.

Main Methods:

• Synthesis and characterization of PEG-PAF copolymers.
• Rheological studies to determine sol-to-gel transition temperatures and concentrations.
• In vitro degradation studies using mammalian proteolytic enzymes.
• In vivo feasibility study using an aqueous insulin formulation in rats.

Main Results:

• PEG-PAF aqueous solutions exhibit a sol-to-gel transition upon heating, observable at low concentrations (3.0-7.0 wt.%).
• The transition is attributed to micellar aggregation and peptide conformational changes from random coils to beta-sheets.
• PEG-PAF is stable in phosphate-buffered saline but degrades in the subcutaneous layer of rats, likely due to proteolytic enzymes.
• A single subcutaneous injection of insulin formulated with PEG-PAF demonstrated a prolonged hypoglycemic effect for 18 days in rats.

Conclusions:

• PEG-PAF hydrogels represent a promising in-situ gelling system for biomedical applications.
• The material's temperature-triggered gelation and tunable degradation profile make it suitable for tissue engineering and drug delivery.
• Further research into PEG-PAF holds potential for advanced cell therapy and sustained drug release formulations.