Silk microspheres for encapsulation and controlled release.

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Protein Engineering

Background:

• Silk fibroin's biocompatibility and biodegradability make it ideal for biomedical applications.
• Controlled release of protein drugs is crucial for effective therapeutic outcomes.
• Developing efficient methods for loading and releasing active proteins from carriers is an ongoing challenge.

Purpose of the Study:

• To develop a method for preparing silk fibroin microspheres using lipid vesicles as templates for efficient protein drug loading.
• To investigate the structural characteristics and drug loading efficiency of the prepared microspheres.
• To evaluate the controlled release profiles and enzyme activity retention of encapsulated model protein drugs.

Main Methods:

• Silk fibroin microspheres were prepared using lipid vesicles as templates.
• Lipid removal was achieved using methanol or sodium chloride treatments.
• Scanning electron microscopy (SEM) was used for surface analysis.
• Horseradish peroxidase was used as a model protein drug for encapsulation and release studies.
• Fluorescein-labeled silk and rhodamine-labeled dextran were used to study drug partitioning.

Main Results:

• Silk microspheres with a beta-sheet structure and approximately 2 µm diameter were successfully prepared.
• Sodium chloride treatment resulted in smoother microsphere surfaces compared to methanol treatment.
• Freeze-thaw cycles during preparation significantly enhanced protein drug loading.
• Enzyme activity was retained during processing and in the final microspheres.
• Release profiles were dependent on the processing method (NaCl vs. MeOH) and influenced by the silk fibroin structure and residual lipids.

Conclusions:

• Silk fibroin microspheres prepared using lipid vesicle templates offer an effective platform for controlled protein drug delivery.
• The microspheres demonstrate good biocompatibility, mechanical toughness, and slow biodegradability.
• The developed method allows for efficient loading of active protein drugs and tunable release kinetics.
• These microspheres hold significant potential for various applications requiring sustained and controlled release of therapeutic proteins.