Light Yellow Powder Alginate In Food 9005-38-3 Alginic Acid Sodium

Above 99% Alginate Sodium With Light Yellow Powder

Sodium alginate is a naturally occurring anionic polymer typically obtained from brown seaweed, it consists of mannuronic (M) and guluronic (G) acids arranged in different combinations (fig. 1) such as blocks rich in either M or G units, or blocks of alternating G and M units. In the presence of divalent Ca²⁺ cations, the guluronic acids from nearby chains form ionic crosslinks resulting in alginate hydrogel. The ratio of M and G units defines the physicochemical properties of the hydrogel..

Sodium alginate gelation process

Alginate hydrogels can be prepared by various cross-linking methods, and their structural similarity to extracellular matrices of living tissues allows wide applications. The most common method to prepare hydrogels from an aqueous alginate solution is to combine the solution with ionic cross-linking agents, such as divalent cations (i.e., Ca2+).

Calcium chloride (CaCl2) is one of the most frequently used agents to ionically cross-link alginate. However, it typically leads to rapid and poorly controlled gelation due to its high solubility in aqueous solutions. One approach to slow and control gelation is to utilize a buffer containing phosphate (e.g., sodium hexametaphosphate), as phosphate groups in the buffer compete with carboxylate groups of alginate in the reaction with calcium ions, and delay gelation. Calcium sulfate (CaSO4) and calcium carbonate (CaCO3), due to their lower solubilities, can also slow the gelation rate and widen the working time for alginate gels. The gelation rate is a critical factor in controlling gel uniformity and strength when using divalent cations, and slower gelation produces more uniform structures and greater mechanical integrity. Finally, thermo-sensitive hydrogels have been widely investigated to date in many drug delivery applications, due to their adjustable swelling properties in response to temperature changes, leading to on-demand modulation of drug release from the gels.