Enhancing the Diffusion Channels of Silica-Alginate Capsules for Microbial Encapsulation

Area of Science:

• Biomaterials Engineering
• Chemical Engineering
• Biotechnology

Background:

• Silica-alginate capsules are utilized in fermentation for cell encapsulation, aiding continuous processes and cell recovery.
• Conventional capsules exhibit poor diffusion, hindering substrate and product transport.
• Improved diffusion is crucial for efficient microbial cell immobilization in bioprocesses.

Purpose of the Study:

• To develop novel silica-coated alginate capsules with enhanced diffusion channels.
• To investigate the effect of a pore-forming agent on capsule diffusion properties.
• To optimize capsule design for improved mass transfer in fermentation.

Main Methods:

• Fabrication of calcium-alginate capsules using a dripping method with CaCl2 and CMC.
• Application of traditional silica coating (G-0) using hydrolyzed 3-aminopropyl triethoxysilane.
• Introduction of glucose as a pore-forming agent (PFA) in varying amounts (0.75, 1.5, 3 g) to create modified capsules (G-0.75, G-1.5, G-3).

Main Results:

• The G-3 capsule, incorporating PFA, exhibited the highest diffusion coefficient ($\left(7.77\pm 0.57\right)\times {10}^{-3}m{m}^2/\min$ at 313.15 K).
• This represents a significant improvement compared to the conventional G-0 capsule ($\left(3.04\pm 0.09\right)\times {10}^{-3}m{m}^2/\min$).
• PFA effectively enhanced membrane porosity and diffusivity.

Conclusions:

• The developed silica-alginate capsules with PFA demonstrate significantly improved diffusion properties.
• This enhancement is crucial for efficient mass transfer in microbial cell immobilization.
• The novel capsules hold promise for advancing fermentation processes and other bioconversion applications.