How hydrophobically modified chitosans are stabilized by biocompatible lipid aggregates

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Hydrogels are versatile materials with numerous applications.
• Biocompatible hydrogels are crucial for biomedical applications like drug delivery.
• Controlling hydrogel nanostructure is key to optimizing their function.

Purpose of the Study:

• To formulate and characterize novel nanostructured hydrogels.
• To investigate the role of hydrophobically modified chitosans and lipid vesicles in hydrogel formation.
• To assess the suitability of these hydrogels for drug delivery.

Main Methods:

• Formulation of hydrogels using hydrophobically modified chitosans (HMCHIT) and lipid vesicles (monoolein and oleic acid/sodium oleate).
• Optimization of gel formation conditions (pH, chitosan modification, component ratios) through visual inspection and rheological experiments.
• Characterization using Electron Paramagnetic Resonance (EPR) and Small-Angle Neutron Scattering (SANS) to confirm nanostructure and lipid bilayer presence.

Main Results:

• An optimal hydrogel system (C12CHIT-MO-NaO in 1:1:1 ratio) was identified, confirmed by rheology.
• EPR confirmed the presence of stabilized lipid bilayers within the hydrogel matrix, even at acidic pH.
• SANS revealed that the hydrophobic tail length of chitosan is critical for stabilizing the polymer network and embedded lipid vesicles.
• Vesicle structural parameters, including lamellar thickness and inter-lamellar distance, were determined and found to be independent of polymer or lipid concentration.

Conclusions:

• A novel, biocompatible, nanostructured hydrogel system has been successfully developed.
• The hydrogel's structure, stabilized by hydrophobically modified chitosans, is suitable for encapsulating lipid vesicles.
• These findings highlight the potential of this nanostructured hydrogel for advanced drug delivery applications.