Prepare a 2.5% solution of sodium alginate in water
Autoclave solution or heat in oven to dissolve alginate (should be yellow and clear)
Mix 20.6 mg calcium carbonate and 74 mg D-glucono-δ-lactone in 1 ml of distilled water (will not dissolve)
Add 1 ml of calcium carbonate/GDL solution to 4 ml of alginate solution in a plastic scintillation vial
Cap the vial and let solution polymerize overnight
After polymerizing overnight, scrap solution into a mortar (largest one available).
Flash-freeze the polymer with liquid nitrogen and use the pestle to crush up the polymer
Add the resulting fine particles to an eppendorf tube and immediately place in the -80 ºC freezer
Freeze-dry