Macromolecule release from monodisperse PLG microspheres: Control of release rates and investigation of release mechanism

Cory Berkland, Emily Pollauf, Chandrashekar Raman, Roshelle Silverman, Kyekyoon Kim, Daniel W. Pack

Research output: Contribution to journalArticlepeer-review

62 Scopus citations


Novel macromolecular therapeutics such as peptides, proteins, and DNA are advancing rapidly toward the clinic. Because of typically low oral bioavailability, macromolecule delivery requires invasive methods such as frequently repeated injections. Parenteral depots including biodegradable polymer microspheres offer the possibility of reduced dosing frequency but are limited by the inability to adequately control delivery rates. To control release and investigate release mechanisms, we have encapsulated model macromolecules in monodisperse poly(D,L-lactide-co-glycolide) (PLG) microspheres using a double-emulsion method in combination with the precision particle fabrication technique. We encapsulated fluorescein-dextran (F-Dex) and sulforhodamine B-labeled bovine serum albumin (R-BSA) into PLG microspheres of three different sizes: 31, 44, and 80 pm and 34, 47, and 85 μm diameter for F-Dex and R-BSA, respectively. The in vitro release profiles of both compounds showed negligible initial burst. During degradation and release, the microspheres hollowed and swelled at critical time points dependant upon microsphere size. The rate of these events increased with microsphere size resulting in the largest microspheres exhibiting the fastest overall release rate. Monodisperse microspheres may represent a new delivery system for therapeutic proteins and DNA and provide enhanced control of delivery rates using simple injectable depot formulations.

Original languageEnglish
Pages (from-to)1176-1191
Number of pages16
JournalJournal of Pharmaceutical Sciences
Issue number5
StatePublished - May 2007

Bibliographical note

Funding Information:
This work was supported in part by NIH Grant EB002878. Scanning electron micrographs were obtained at the Center for Microanalysis of Materials, University of Illinois, which is partially supported by the U.S. Department of Energy under grant DEFG02-91-ER45439.


  • Bovine serum albumin
  • Controlled release
  • Dextran
  • Poly(D,L-lactide-co-glycolide)
  • Uniform microspheres

ASJC Scopus subject areas

  • Pharmaceutical Science


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