Effect of polymer compositions on the fabrication of Poly(ortho-ester) microspheres for controlled release of protein

Xin Lai Bai, Yi Yan Yang, Tai Shung Chung*, Steve Ng, Jorge Heller

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Eight kinds of self-catalyzed poly(ortho-esters) (POEs) are used to fabricate bovine serum albumin (BSA)-containing microspheres using a W/O/W double-emulsion solvent extraction/evaporation method. All eight kinds of POE polymers used in this study are shown able to form microspheres under proposed fabrication conditions. The surface morphology and inner structure of the microspheres are analyzed using scanning electron microscopy (SEM). The microspheres have a size range from 64.7 to 120.2 μm. POE with a higher viscosity leads to bigger microspheres. It was found that the POE composition has a significant effect on BSA release profiles. POEs, which are more hydrophilic and contain a greater amount of glycolide or lactate (latent acid), yield higher BSA release rates. Specifically, POE containing 1,6-hexanediol diglycolide (HD-diGL) microspheres have the highest BSA release rate after a 20-day test through a combination of surface erosion and diffusion mechanisms. POE containing a high percentage of the trans-cyclohexanedimethanol (CDM) segment tends to yield microspheres with a lower release rate because of its hydrophobic nature. It was also found that the BSA release rate is more rapid at 37°C than at 22°C because of faster polymer degradation and water penetration at 37°C. Experimental results suggest that various protein release rates can be achieved by using different compositions of POEs.

Original languageEnglish (US)
Pages (from-to)1630-1642
Number of pages13
JournalJournal of Applied Polymer Science
Issue number10
StatePublished - Jun 6 2001
Externally publishedYes


  • Bovine serum albumin
  • Microspheres
  • Poly(ortho-ester)s
  • Release profile
  • Surface erosion

ASJC Scopus subject areas

  • General Chemistry
  • Surfaces, Coatings and Films
  • Polymers and Plastics
  • Materials Chemistry


Dive into the research topics of 'Effect of polymer compositions on the fabrication of Poly(ortho-ester) microspheres for controlled release of protein'. Together they form a unique fingerprint.

Cite this