Preparation of Sodium Alginate Hydrogel and Its Application in Drug Release

In recent years, due to an attractive application prospect of intelligent hydrogel in drug controlled release, gene transfer, tissue engineering and other fields, the research about intelligent hydrogel is very active. The synthetic hydrogels are mainly prepared by acrylic acid and its derivatives, acrylamide and its derivatives. Synthetic hydrogel has good stability, but its biodegradability and biocompatibility are poor. The raw materials of natural hydrogel include chitosan, sodium alginate, cellulose, starch, etc. These polysaccharides have good biocompatibility and biodegradability, and at the same time, they are cheaper and easier to manufacture. As a result, the natural hydrogels are superior to synthetic hydrogels for drug controlled release. Sodium alginate is an anionic linear polysaccharide composed of (1 -> 4)-beta-D-mannuronic acid (M) and (1 -> 4)-alpha-L-guluronic acid (G). Each uronic acid unit contains a carboxyl group, under neutral or basic conditions, sodium alginate shows the properties of the polyanion electrolyte. In this review, the preparation methods of sodium alginate hydrogel are introduced in detail, including physical crosslinking, chemical crosslinking, enzymatic crosslinking, interpenetrating polymer network. The application of sodium alginate hydrogel in drug release is also introduced, including oral administration, subcutaneous administration, mucosal administration, pulmonary administration, transdermal administration. Finally, the problems in research and prospect of sodium alginate hydrogels are discussed.