A novel indicator-based visualisation method to investigate diffusion behaviour of dissolved CO₂ in hydrogels

Area of Science:

• Biotechnology
• Materials Science
• Chemical Engineering

Background:

• Biocompatible hydrogels are crucial for cell encapsulation in biotechnology.
• Efficient dissolved carbon dioxide (dCO2) diffusion is vital for immobilised photosynthetic cells.
• Existing non-invasive methods for measuring dCO2 diffusion in hydrogels are limited.

Purpose of the Study:

• To develop and validate an indirect, non-invasive method for measuring dCO2 diffusion rates in hydrogels.
• To provide insights into dCO2 diffusion dynamics within different hydrogel matrices.
• To facilitate the design of improved immobilization matrices for photosynthetic microorganisms.

Main Methods:

• Utilized pH indicator-doped hydrogel monoliths to visualize dCO2 diffusion.
• Tracked the interface position along the axial direction over time.
• Calculated interface velocity and pseudo diffusion coefficients (Dpseudo).

Main Results:

• The developed method provides non-invasive and rapid estimation of dCO2 diffusion.
• Automatic analysis of color interface formation due to hydrogel acidification by dCO2.
• Agarose hydrogels demonstrated approximately 30x higher pseudo dCO2 diffusion coefficients compared to silica gel.

Conclusions:

• The novel method offers valuable insights into dCO2 diffusion dynamics in hydrogels.
• This technique can significantly aid in optimizing hydrogel-based immobilization matrices.
• The findings support the advancement of biotechnological applications involving photosynthetic cells.