Colloidal characteristics and functionality of rationally designed esculin-loaded hydrogel microcapsules

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Nanotechnology

Background:

• Alginate hydrogel microparticles are promising for drug delivery.
• Controlling the release of hydrophilic compounds from porous microparticles remains a challenge.

Purpose of the Study:

• To develop alginate microparticles with polyelectrolyte shells for esculin (ESC) encapsulation.
• To investigate the impact of shell properties on ESC release kinetics and stability.

Main Methods:

• Ionotropic gelation for alginate microsphere preparation.
• Electrostatic complexation for polyelectrolyte shell adsorption (chitosan, gelatin, PAH, PSS).
• Advanced characterization (microscopy, QCM-D, ellipsometry, streaming potential) and in vitro release studies.

Main Results:

• Microparticles with poly(allylamine hydrochloride)-poly(4-styrenesulfonate) (PAH-PSS) and gelatin (GEL) shells demonstrated significant protection against ESC release.
• Release kinetics under simulated gastric conditions followed a two-stage Corrigan-Gallagher model with an initial lag phase.
• A novel approach combined multiple techniques to correlate shell properties with release behavior.

Conclusions:

• Polyelectrolyte coatings can effectively modulate the release of hydrophilic drugs from alginate microparticles.
• The observed two-stage release mechanism is unusual for porous microhydrogels and warrants further investigation.
• This study provides a new methodology for characterizing microparticle-drug interactions and optimizing drug delivery systems.