Forces between insulin microspheres and polymers surfaces for a dry powder inhaler

Area of Science:

• Materials Science
• Biophysics
• Pharmaceutical Engineering

Background:

• Solid protein microspheres in inhalation devices interact with polymer surfaces under ambient conditions.
• Understanding particle-device interactions is crucial for optimizing drug delivery systems.

Purpose of the Study:

• To compare interactions between insulin microspheres and common device polymers using atomic force microscopy.
• To evaluate the influence of antistatic additives and relative humidity on these interactions.

Main Methods:

• Utilized a colloidal probe atomic force microscope (AFM) to measure adhesion forces.
• Tested interactions between insulin microspheres and polytetrafluoroethylene, polyethylene, and polypropylene (with/without antistatic additive).
• Investigated particle-device interactions across a range of relative humidities.

Main Results:

• Results clearly distinguished between polymer types and the effect of antistatic additives.
• Polypropylene with antistatic additive exhibited consistent, low interaction forces across all humidity levels.
• At 80% relative humidity, all polymers showed similar adhesion forces, likely due to charge mitigation and hydration.

Conclusions:

• Direct measurement of adhesion forces aids in selecting appropriate plastics and coatings for medical devices.
• Polypropylene with antistatic additive appears promising for minimizing insulin microsphere adhesion in delivery devices.
• Particle-device interactions are significantly influenced by polymer choice, additives, and environmental humidity.