Earth sand alginate gel (30% 150µm earth sand, 9% CMC, 3% alginate solution, made on 250610)
Spatula
1 mL syringe
microscope slide + cover slip
light microscope
Methods
To prepare the microscope slide, place 200 μl of the bio-ink (using a 1mL syringe) onto a glass slide and press it with a coverslip. Make sure there are no air bubbles.
Repeat step 1 but use pure alginate with no CMC or earth sand
Mount the slide onto a black surface and below the microscope
Start the video recording on your camera.
Pipette 200 μl of an aqueous solution of 100 mM calcium chloride. Make sure to do this on ONE side of the coverslip border. Don’t cover the entire sample. The Ca2+ ions will diffuse as a flat front along the hydrogel
Let the slide sit and record for 30 minutes.
Save the video. It will be used to measure the diffusion distance pixel by pixel.
Results
Figure 3. ~200 μl alginate solution with ~100 μl of calcium chloride added on slide with cover slip (prominent line down the middle). Green arrow indicates the diffusion direction.
Observations
100 μl calcium chloride solution was used for 200 μl alginate solution on the coverslip. It seems the calcium chloride solution started to diffuse through the alginate solution under microscope, but we need to wait a longer time to verify
40 μl calcium chloride solution was used for 200 μl earth sand alginate gel (30wt% 150 μm sieved sand, 9%CMC, 3% alginate solution) on the coverslip. The earth sand alginate gel did not show any calcium chloride diffusion under the microscope.
Summary
Calcium chloride diffusion was not observed with 30wt% 150 μm sieved sand, 9%CMC, 3% alginate solution on coverslip
calcium chloride diffusion observed in alginate control sample, indicating possible issue where earth sand composition is interfering with calcium diffusion ability
