Biocompatibility and physicochemical characteristics of alginate-polycation microcapsules

Area of Science:

• Biomaterials Science
• Immunology
• Chemical Engineering

Background:

• Alginate-polycation microcapsules are promising for various applications.
• Understanding their biocompatibility is crucial for effective use.
• Physicochemical properties significantly influence biological interactions.

Purpose of the Study:

• To investigate how physicochemical characteristics of alginate-polycation microcapsules affect their biocompatibility.
• To compare the performance of microcapsules with different alginate compositions, gelling agents, and polycation coatings.
• To elucidate the role of alginate-polycation interactions in microcapsule membrane formation and immune response.

Main Methods:

• Fabrication of alginate microcapsules with varying guluronate content (IntG, HiG), gelling ions (Ca, Ba), and polycations (PLL, PLO).
• Assessment of immune cell adhesion in vivo (C57BL/6J mice).
• Evaluation of hydrophilicity, swelling resistance, and membrane integrity under osmotic stress.
• Surface and bulk analysis using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS).

Main Results:

• Poly-L-ornithine (PLO) coated microcapsules showed reduced immune cell adhesion and improved osmotic resistance compared to poly-L-lysine (PLL) coated ones.
• PLL membrane integrity was compromised by poor penetration into IntG(Ca) gel cores, leading to increased immune response when using IntG(Ba) or HiG(Ca) gels.
• Surface polycation concentration was similar across all tested microcapsules, and alginate coatings had minimal impact on biocompatibility and properties.

Conclusions:

• Alginate-polycation interactions during membrane formation are critical determinants of microcapsule biocompatibility.
• The choice of polycation (PLO vs. PLL) significantly impacts microcapsule performance and immune response.
• Microcapsule physicochemical properties, particularly membrane integrity and hydrophilicity, are key to minimizing adverse biological reactions.