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Surface characterization of poly(alpha-hydroxy acid) microspheres prepared by a solvent evaporation/extraction
F Boury1, H Marchais, J P Benoit
1Laboratoire de Pharmacie Galénique et Biophysique Pharmaceutique, Faculté de Pharmacie, Angers, France.
Biomaterials
|January 1, 1997
Summary
This study characterizes poly(alpha-hydroxy acid) (PAHA) microsphere wettability. Emulsifier type and formulation method significantly impact surface properties and water interaction, influencing their potential applications.
Area of Science:
- Materials Science
- Surface Chemistry
- Polymer Science
Background:
- Poly(alpha-hydroxy acid) (PAHA) microspheres are complex to characterize.
- Understanding their surface properties, particularly wettability, is crucial for applications.
Purpose of the Study:
- To characterize the in situ wettability of PAHA microspheres.
- To investigate the influence of emulsifiers (poly(vinyl alcohol) - PVA, and bovine serum albumin - BSA) on PAHA microsphere surface properties.
Main Methods:
- Microsphere preparation via emulsification, solvent evaporation, washing, and freeze-drying.
- Contact angle measurements (advancing and receding) using flotation profiles.
- Analysis of model surfaces with PAHA, PVA, BSA, and mixed monolayers on glass and PMMA substrates.
Main Results:
- Emulsifiers (PVA, BSA) were strongly anchored to PAHA microsphere surfaces.
- BSA-formulated microspheres showed hydrophobic surfaces that became more wettable upon water immersion due to BSA unfolding.
- PVA-stabilized single emulsions yielded similar wettability changes.
- Double emulsion microspheres exhibited no wettability change, attributed to immobile hydrophilic segments.
Conclusions:
- The formulation method and emulsifier choice critically determine PAHA microsphere surface wettability.
- BSA and PVA emulsifiers influence wettability through structural changes upon water exposure.
- Microsphere wettability can be tailored by controlling emulsifier mobility within the polymer matrix.