Ice templating water-stable macroporous polysaccharide hydrogels to mimic plant stems

Area of Science:

• Materials Science
• Biomaterials Engineering
• Soft Matter Physics

Background:

• Plant stems exhibit efficient passive liquid transport due to their unique macroporous structure.
• Developing synthetic materials that mimic this functionality, particularly hydrogels, faces challenges in controlling pore size and ensuring water stability.
• Existing methods for creating porous hydrogels are often complex and energy-intensive.

Purpose of the Study:

• To develop water-stable macroporous hydrogels inspired by plant stem xylem for passive liquid transport.
• To establish a novel fabrication method that allows for tunable pore sizes and avoids energy-intensive processes.
• To investigate the relationship between material composition, fabrication parameters, and liquid transport properties.

Main Methods:

• Fabrication of composite hydrogels using alginate and TEMPO-oxidized cellulose.
• Employing ice templating to create macroporous structures.
• Utilizing topotactic ion-crosslinking with Ca2+ for water stability.
• Controlling pore size by adjusting ice growth velocities and polymer ratios.

Main Results:

• Successfully fabricated water-stable macroporous hydrogels with pore sizes comparable to celery xylem.
• Demonstrated tunable pore size by controlling ice growth velocity and alginate-to-cellulose ratio.
• Achieved liquid transport speeds in hydrogels comparable to natural plant stems.
• Observed that mechanical properties (compression stress, toughness) increase with higher alginate content.
• Hydrogel wettability and viscoelasticity are dependent on the alginate and oxidized cellulose ratios.

Conclusions:

• The developed ice templating and topotactic ion-crosslinking method is effective for creating plant stem-inspired hydrogels.
• These polysaccharide-based hydrogels exhibit excellent water stability and tunable liquid transport capabilities.
• The biocompatibility of these materials suggests significant potential for soft liquid transport systems in biological and environmental applications.