Spray-dried microparticles containing polymeric nanocapsules: formulation aspects, liquid phase interactions and...

Area of Science:

• Colloid and Surface Chemistry
• Materials Science
• Nanotechnology

Background:

• Polymer-based nanoparticles (NC) exhibit limited stability in aqueous media, hindering their full application potential.
• Developing stable, solid-state forms of nanocapsules is crucial for improved handling and storage.

Purpose of the Study:

• To investigate the spray-drying of nanocapsule dispersions using colloidal silicon dioxide as a drying auxiliary.
• To evaluate the impact of formulation parameters on suspension behavior and powder characteristics.
• To achieve stable, dried nanocapsule powders suitable for further applications.

Main Methods:

• Spray-drying of nanocapsule dispersions with varying colloidal silicon dioxide concentrations.
• Rheological measurements to assess suspension behavior and interactions.
• Scanning Electron Microscopy (SEM) for powder morphology analysis.
• Electron Spectroscopy for Chemical Analysis (ESCA) for surface composition investigation.

Main Results:

• Formulation parameters, including mixing protocols and concentrations of nanocapsules (NC) and silica, significantly influence feed behavior and spray-dried particle characteristics.
• Rheological studies indicated hydrogen bonds direct interactions, with sensitivity to silica concentration.
• Adequate silica concentrations resulted in spherical, separated microparticles where NC are entrapped within a solid silica matrix.
• Insufficient silica led to fused, irregular agglomerated particles with poor handling properties.

Conclusions:

• Spray-drying with colloidal silicon dioxide is an effective method for obtaining stable, solid nanocapsule forms.
• Optimizing the concentration of colloidal silicon dioxide is critical for controlling particle morphology and achieving desirable powder characteristics.
• The developed method yields powders with nanocapsules excluded from the surface, enhancing suitability for handling and further processing.