Quantification of microparticle coating quality by confocal laser scanning microscopy (CLSM)

Area of Science:

• Materials Science
• Pharmaceutical Technology
• Analytical Chemistry

Background:

• Accurate characterization of microparticle coatings is essential for drug delivery and product performance.
• Traditional methods for assessing coating thickness and quality can be destructive or lack precision for individual particles.

Purpose of the Study:

• To develop and validate a novel protocol using confocal laser scanning microscopy (CLSM) for non-destructive determination of film coating thickness and quality on microparticles.
• To assess the influence of process parameters on microparticle coating quality using the developed CLSM method.

Main Methods:

• Development of a CLSM-based protocol for imaging and quantifying coating thickness on individual microparticles.
• Application of image analysis techniques to determine coating thickness distribution.
• Validation of CLSM results against chemical analysis for coating thickness.
• Investigation of protein-coated microparticles produced via fluidized bed coating.

Main Results:

• CLSM proved to be an adequate non-destructive technique for quantifying coating thickness and quality of thin-coated microparticles.
• High accuracy in determining coating thickness distribution was achieved when combined with image analysis.
• CLSM data showed good agreement with chemical analysis for coating thicknesses down to 1-1.5 micrometers.
• Coating quality decreased with increased distance between the coating nozzle and powder bed, and with increased coating droplet viscosity.

Conclusions:

• The developed CLSM protocol is a reliable and accurate method for characterizing microparticle coatings.
• CLSM provides valuable insights into process-parameter optimization for fluidized bed coating.
• Understanding the impact of nozzle distance and droplet viscosity is critical for achieving high-quality microparticle coatings.