A morphological screening of protein crystals for interferon delivery by metal ion-chelate technology

Abstract

Objective: This study presents a preliminary exploration on extending the half-life of therapeutic proteins by crystallization strategy without new molecular entities generation. Methods: Recombinant human interferon (rhIFN) α-2b, a model protein drug in this case, was crystallized using a hanging-drop vapor diffusion method. A novel chelating technique with metal ions was employed to promote crystals formation. Results: The effects of key factors such as seeding protein concentration, pH of the hanging drop, ionic strength of the equilibration solution, and precipitants were investigated. Size-exclusion liquid chromatography, antiviral activity determination, and enzyme-linked immunosorbent assay indicated that both the molecular integrity and biological potency of rhIFN were not significantly affected by crystallization process. In addition, the in vitro release behavior of rhIFN from crystal lattice was characterized by an initial fast release, followed by a sustained release up to 48 hour. Conclusion: The work described here suggested an exciting possibility of therapeutic protein crystals as a long-acting formulation.

Keywords:

• Bioactivity
• crystallization
• interferon
• morphology
• sustained release

Acknowledgments

The authors wish to thank the National Natural Science Foundation of China (No. 30701057) and the scientific research plan projects of Liaoning Education Department (No. 2009A806) for their financial support.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper.