In vitro degradation of polyanhydride/polyester core-shell double-wall microspheres

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Drug Delivery Systems

Background:

• Double-wall microspheres (DWMS) offer potential for controlled drug release.
• Surface-eroding polymers are hypothesized to limit water penetration and slow core degradation.
• Understanding polymer erosion is crucial for designing effective drug delivery vehicles.

Purpose of the Study:

• To investigate the erosion and degradation behavior of DWMS fabricated with surface-eroding and bulk-eroding polymers.
• To evaluate the impact of polymer shell composition on water penetration and core degradation.
• To assess the controlled-release potential of DWMS under simulated physiological conditions.

Main Methods:

• Fabrication of solid microspheres and DWMS using poly(1,6-bis(p-carboxyphenoxy)hexane) (PCPH) as a surface-eroding polymer and poly(D,L-lactide-co-glycolide) (PLG) as a bulk-eroding polymer.
• Observation of particle erosion using optical and electron microscopy.
• Monitoring of polymer degradation via gel permeation chromatography during incubation in buffer at 37°C.

Main Results:

• Erosion and degradation patterns varied significantly based on the polymer forming the microsphere shell.
• Thin (approximately 5 µm) PCPH shells did not effectively impede water penetration into the microspheres.
• The PLG cores within the DWMS underwent complete erosion by the end of the 6-week incubation period.

Conclusions:

• The anticipated limitation of water penetration by surface-eroding polymer shells in DWMS was not achieved.
• The choice of shell polymer significantly influences the degradation profile of DWMS.
• Further optimization of shell thickness and material properties is necessary for effective controlled drug release using this DWMS system.