Stabilization and encapsulation of a staphylokinase variant (K35R) into poly(lactic-co-glycolic acid) microspheres

Jin Tian He, Hua Bo Su, Guo Ping Li, Xian Mei Tao, Wei Mo, Hou Yan Song

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


The aim of this study is to prepare poly(lactic-co-glycolic acid) (PLGA) microspheres containing a staphylokinase variant K35R (DGR) with purpose of preserving the protein stability during both encapsulation and drug release. DGR-loaded microspheres are fabricated using a double-emulsion solvent extraction technique. Prior to encapsulation, the effect of ultrasonication emulsification of DGR solutions with methylene chloride on protein recovery was investigated. Moderate ultrasonic treatment of aqueous DGR/dichloromethane mixtures caused approximately 84% DGR aggregation. Polyvinyl alcohol (PVA) added into aqueous DGR solutions significantly improved DGR recovery to >90%. The effects of co-encapsulated PVA and NaCl in the external aqueous phase on the characteristics of the microspheres were investigated. When 2% PVA was co-encapsulated and 2.5% NaCl was added to the external water phase, DGR encapsulation efficiency was significantly increased from 7.1% to 78.1% and DGR was distributed uniformly throughout the microspheres. In vitro release test showed that DGR was released from PLGA microspheres in a sustained manner over 15 days. A large amount of released DGR was inactive in the absence of co-encapsulated PVA. On the contrary, when 2% PVA was co-encapsulated, the released DGR was almost completely intact within 9 days. In conclusion, PLGA microspheres can be an effective carrier for DGR and form a promising depot system.

Original languageEnglish (US)
Pages (from-to)101-108
Number of pages8
JournalInternational Journal of Pharmaceutics
Issue number1-2
StatePublished - Feb 17 2006
Externally publishedYes


  • Microspheres
  • Polyvinyl alcohol
  • Protein delivery
  • Protein stability
  • Staphylokinase

ASJC Scopus subject areas

  • Pharmaceutical Science


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