Protein immobilization in crosslinked alginate microparticles.

Area of Science:

• Biomaterials Science
• Pharmaceutical Technology
• Drug Delivery Systems

Background:

• Oral delivery of peptide and protein drugs is challenging due to gastro-intestinal degradation.
• Effective drug carriers are needed to protect sensitive biomolecules and target absorption sites.

Purpose of the Study:

• To develop and evaluate alginate microsystems for oral protein drug delivery.
• To investigate the impact of formulation variables (Na-A/BSA ratio, crosslinking pH) on microsystem properties.
• To assess protein stability and release characteristics within the microsystem.

Main Methods:

• Spray-drying technique for alginate microsystem fabrication.
• Crosslinking with Ca2+ and chitosan (CS) for enhanced stability.
• Evaluation of microsystem morphology, BSA loading, encapsulation efficiency, and in vitro release.
• Polyacrylamide gel electrophoresis (PAGE) for protein stability assessment.

Main Results:

• Microsystem characteristics were largely unaffected by formulation variables.
• Higher BSA loading was achieved at pH values below the protein's isoelectric point due to electrostatic interactions.
• Maximum encapsulation efficiency correlated with the highest sodium alginate (Na-A) to bovine serum albumin (BSA) ratio.
• Protein release was primarily governed by the pH-dependent properties of the alginate material, not preparative variables.
• PAGE confirmed protein stability throughout preparation and simulated gastro-intestinal conditions.

Conclusions:

• Alginate microsystems offer a promising approach for oral protein drug delivery.
• Formulation parameters, particularly pH and polymer-to-protein ratio, influence encapsulation efficiency.
• The developed microsystems provide adequate protection and controlled release of model protein (BSA).
• The study highlights the potential of these microsystems for enhancing oral bioavailability of protein therapeutics.