Use of thermodynamic parameters for design of double-walled microsphere fabrication methods

Emily J. Pollauf, Daniel W. Pack

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Double-walled microspheres (DWMS), with drug localized to the particle core, present a promising route for control of drug release rates, for example, by varying the degradation rate or erosion mechanism of the polymer used to form the shell or the thickness of the shell. DWMS are often difficult to fabricate, however. Thermodynamic descriptions for polymer-polymer immiscibility, drug distribution between phases and polymer-solution spreading coefficient provide predictions of appropriate solvents and polymer concentrations for efficiently producing well-formed DWMS. As an example, thermodynamic parameters for a polyphosphoester/poly(d,l-lactide-co-glycolide) (PLG) DWMS system, encapsulating piroxicam, have been calculated and the predictions tested experimentally. Appropriate choices of solvents and initial polymer concentrations resulted in DWMS with the desired polyphosphoester shells and piroxicam located selectively in PLG cores.

Original languageEnglish
Pages (from-to)2898-2906
Number of pages9
Issue number14
StatePublished - May 2006

Bibliographical note

Funding Information:
This work was supported by NIH Grant 1-R21-EB002878. We thank Prof. Kevin Kim for use of the PPF apparatus used in production of all particles reported herein. The gifts of piroxicam from Dong Wha Pharmaceuticals and PLF from Guilford Pharmaceuticals are also gratefully acknowledged. Scanning electron microscopy was carried out at the Center for Microanalysis of Materials, University of Illinois at Urbana-Champaign, which is partially supported by the US Department of Energy under Grant DEFG02-91-ER45439.


  • Controlled drug release
  • Double-walled microspheres
  • Microcapsules
  • Microencapsulation
  • Piroxicam

ASJC Scopus subject areas

  • Mechanics of Materials
  • Ceramics and Composites
  • Bioengineering
  • Biophysics
  • Biomaterials


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