Mechanical characterization of biocompatible microspheres and microcapsules by direct compression

Area of Science:

• Biomaterials Science
• Materials Engineering
• Biophysics

Background:

• Biocompatible microparticles are crucial in drug delivery and tissue engineering.
• Understanding their mechanical properties is essential for optimizing their performance and predicting their behavior in biological environments.
• Alginate and chitosan are widely used biopolymers for microparticle fabrication due to their biocompatibility and tunable properties.

Purpose of the Study:

• To characterize and compare the mechanical properties of alginate microspheres and alginate-chitosan microcapsules.
• To investigate the influence of compression speed, holding time, and wall thickness on the mechanical response of these microparticles.
• To determine the rupture force and deformation characteristics of the microparticles under mechanical stress.

Main Methods:

• Utilized a micromanipulation technique to compress individual microparticles (20-60 micrometers in diameter).
• Measured the force response using a force transducer during compression to a specific deformation and during compression to rupture.
• Varied compression speeds and wall thickness (for microcapsules) to assess their impact on mechanical behavior.

Main Results:

• Force increased upon compression, with significant relaxation when held; alginate microspheres showed greater relaxation than alginate-chitosan microcapsules.
• Higher compression speeds resulted in greater force for alginate microspheres at a given deformation.
• Alginate-chitosan microcapsules exhibited less force relaxation with thicker walls; rupture force was generally higher for microcapsules, independent of compression speed for deformation at rupture.

Conclusions:

• Alginate-chitosan microcapsules offer improved mechanical stability and higher rupture strength compared to alginate microspheres, making them potentially superior for applications requiring mechanical resilience.
• Wall thickness significantly influences the force relaxation behavior of alginate-chitosan microcapsules.
• The mechanical properties, particularly rupture force and relaxation, are dependent on material composition and structural parameters like wall thickness.