Preparation And Properties Of Natural Macromolecular Film And Gel Materials

Potato starch and sodium alginate are abundant natural polymers in nature and are widely used in food,medicine and other industries due to their convenience,renewable,biodegradable and biocompatible characteristics.Potato starch has excellent gelation,film formation and other properties,so it is suitable for preparing edible and packaging films.Sodium alginate molecule contains a large amount of hydroxyl groups and carboxyl groups so that it can be crosslinked with metal ions such as Ag⁺to form gel that can be used as a drug-loading carrier.This paper will focus on the above two aspects that will be described as follows:（1）A series of potato starch composite films were prepared by physical mixing,and their amorphous structure and properties were studied.The interaction between the two-dimensional sheet-like g-C₃N₄ nanosheets and potato starch matrix through intermolecular hydrogen bonding improved the thermal stability and mechanical properties of the films.The tensile strength of the film was increased by 214%when the g-C₃N₄ nanosheets content was 8 wt%.UV light and synchronous fluorescence spectroscopy analyses show that the composite films have UV absorption capacity as the content of g-C₃N₄ nanosheets is high（>4 wt%）,so it can be used as an ultraviolet shielding material to protect edible oil or other oily foods.（2）Sodium alginate gel spheres loaded with drug were prepared by drop different amounts of sodium alginate solution into Ag⁺solution which was used as a crosslinking agent.The preparation condition,sphere morphology and in vitro drug release behavior of sodium alginate gel spheres were investigated.A good shape alginate gel sphere can be formed as the sodium alginate solution is higher than 1 wt%and the Ag⁺solution is higher than 1.5 wt%.The results of in vitro simulated drug release of gel spheres indicate that the drug release was affected by some factors:the release rate of the drug in simulated intestinal fluid was lowered along with the increase of sodium alginate content,when the solubility of the drug changes,the release rate will change accordingly.（3）SA/G gel spheres with interpenetrating network structure were prepared by a stepwise cross-linking method with Ag⁺and glutaraldehyde as cross-linking agents.The gel sphere with IPN structure could stably stay in PBS with p H=7.4,which meets the requirement of sustained release of drug in p H 7.4 condition.The swelling degree of gel spheres reached the maximum when gelatin was 0.1 wt%,and the nimesulide loaded in the gel spheres could be continuously released for 12to reach a drug release amount of 83.6%.