Supramolecular hydrogels based on self-assembly between PEO-PPO-PEO triblock copolymers and alpha-cyclodextrin

Area of Science:

• Polymer Science
• Materials Chemistry
• Biomaterials Engineering

Background:

• Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers are known for their thermosensitive and self-assembling properties.
• Alpha-cyclodextrin (alpha-CD) is a cyclic oligosaccharide capable of forming inclusion complexes with hydrophobic molecules.

Purpose of the Study:

• To investigate the hydrogel formation of PEO-PPO-PEO triblock copolymers induced by alpha-cyclodextrin in aqueous solutions.
• To characterize the gelation kinetics, rheological properties, and sol-gel phase transitions.
• To elucidate the mechanism of gelation and assess the potential of these hydrogels for drug delivery applications.

Main Methods:

• Viscometry was employed to study gelation kinetics and rheological properties.
• Phase diagrams were utilized to analyze sol-gel phase transitions.
• Differential scanning calorimetry (DSC) was used to investigate the gelation mechanism.

Main Results:

• The addition of alpha-CD significantly reduced the copolymer concentration required for gel formation.
• Complex formation between PEO segments and alpha-CD, followed by self-assembly, was identified as the primary gelation mechanism.
• The resulting hydrogels exhibited thixotropic and reversible behavior.

Conclusions:

• Alpha-cyclodextrin effectively induces hydrogel formation in PEO-PPO-PEO copolymers at lower concentrations.
• The self-assembly of inclusion complexes drives the gelation process.
• These PEO-PPO-PEO/alpha-CD hydrogels show potential as injectable drug-delivery systems due to their reversible and thixotropic nature.