Research Paper

Pharmaceutical Research

, Volume 23, Issue 6, pp 1295-1305

First online:

The Influence of Surfactant on PLGA Microsphere Glass Transition and Water Sorption: Remodeling the Surface Morphology to Attenuate the Burst Release

  • C. BouissouAffiliated withDepartment of Pharmacy, University of Bath
  • , J. J. RouseAffiliated withDepartment of Pharmaceutical Sciences, University of Strathclyde
  • , R. PriceAffiliated withDepartment of Pharmacy, University of Bath
  • , C. F. van der WalleAffiliated withDepartment of Pharmaceutical Sciences, University of Strathclyde Email author 

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Purpose

The stability of protein unloaded and loaded poly(lactic-co-glycolic acid) (PLGA) microspheres fabricated with surfactant was challenged through exposure to environmental conditions of different relative humidity.

Methods

Polyvinyl alcohol (PVA) or Triton X-100 was added to the primary emulsion of the double-emulsion solvent evaporation technique. After storage at ambient humidity and 75% relative humidity, the mechanical stability of the polymer was tested to reveal PLGA chain mobility using differential scanning calorimetry. Subsequent surface modifications were examined by atomic force microscopy (AFM), and protein release profiles were collected.

Results

Residual amounts of PVA and particularly Triton X-100 raised the hydrophilicity of the microspheres. When exposed to ambient humidity or 75% relative humidity, PVA and Triton X-100 had, respectively, an antiplasticizing and a plasticizing effect upon PLGA, and both led to physical aging. The high-resolution AFM imaging of microspheres containing model protein and Triton X-100 showed that the depth of the surface pores was reduced when exposed to 75% relative humidity, and the initial burst release subsequently decreased.

Conclusion

These studies suggested that the mechanical stability of PLGA was influenced by the addition of surfactants, which, depending on the formulation, led to surface pore remodeling under high humidity, reducing the initial burst release while maintaining the spherical integrity of the microsphere.

Key Words

burst release plasticization PLGA glass transition pore remodeling relative humidity surfactant