Air-filled polymeric microcapsules from emulsions containing different organic phases

Area of Science:

• Materials Science
• Biomedical Engineering
• Acoustics

Background:

• Ultrasonography requires effective contrast agents for enhanced imaging.
• Air-filled polymeric microcapsules offer potential as ultrasound contrast agents.
• Current methods for microcapsule production face challenges in scalability and efficiency.

Purpose of the Study:

• To develop air-filled polymeric microcapsules for ultrasound contrast imaging.
• To investigate the use of freeze-drying for microcapsule preparation.
• To evaluate different organic solvents for their impact on microcapsule properties and yield.

Main Methods:

• Preparation of oil-in-water emulsions with a biodegradable polyester in organic solvents and a block copolymer in water.
• Utilizing freeze-drying to precipitate a polymeric wall and create air-filled microcapsules.
• Characterization of microcapsule size, morphology, and acoustic properties using microscopy and acoustic attenuation measurements.

Main Results:

• Successfully produced air-filled polymeric microcapsules with a mean diameter of 5-7 micrometers.
• Microcapsules were spherical, hollow, and echogenic.
• Cyclooctane and cyclohexane solvents resulted in improved yields and acoustic attenuation compared to (-)-camphene and tricyclene.
• (-)-Camphene and tricyclene were deemed unsuitable for industrial production due to their high melting points.

Conclusions:

• Freeze-drying is a viable method for producing air-filled polymeric microcapsules for ultrasound contrast.
• Cyclooctane and cyclohexane are promising solvents for scalable industrial production of these microcapsules.
• Further optimization of the freeze-drying process could enhance microcapsule performance.