Preparation Of Acetylated Starch Microspheres

Starch and starch derivatives nanospheres have been widely used in the release of drug, the adsorption of heavy metals and the treatment of sewage, owing to their significant advantages, such as biocompatible, biodegradable, non-toxic, storage stability, extensive source, low cost. We synthesized shortest carbon chain hydrophobic acetylated starch and fabricated acetylated starch nanospheres by dialysis and nanoprecipitation. The method was based on the hydrophobic starch derivatives nanospheres prepared. The paper gave a detail study on the effects of particle morphology, monodisperse and size.With glacial acetic acid as the solvent, methanesulphonic as the catalyst, acetylated corn starches were synthesized with starch and acetic anhydride. When the molar ratio of the starch saccharide units to acetic anhydride to methyl sulfonic acid was1:5.3:0.06, the temperature was75℃for3h, the degree of substitution reached2.89. The products were characterized by FTIR spectroscopy and1H-NMR.Taking acetylated starch of variant DS as raw materials, acetylated starch nanospheres were fabricated by dialysis and nanoprecipitation. The two methods maked use of the different solubility of acetylated starch in the two miscible solvents which were named the solvent and non-solvents. When they encountered, the natural mixing of the interface between the two non-equilibrium phase, including flow, diffusion and interface action, the precipitation occured followed by the forming of the acetylated starch microspheres. Without the surfactants and crosslinkers, the morphology, size and monodisperse of the microspheres obtained could be easily controlled by a number of simple and efficient modifications.When we prepared acetylated starch microspheres by dialysis, we studied the influencing factors of morphology, size and monodiepersity of the microspheres, which included the DS of the starch esters, the type of solvent, the concentration of acetylated starch in solvent and its molecular weight. The results showed that the morphology of the product was close to spherical with increasing DS, when the DS was2.89, we could obtain the best spherical morphology microspheres. The morphology of the microsphere was better and the size was larger acetone as good solvent than DMSO. The size of the microspheres increased with increasing concentration, and decreased with increasing molecular weight. The particle size and polydispersity of nanospheres in aqueous solution were measured by dynamic light scattering, The appearance of nanospheres was characterized by scanning electron microscopy (SEM). When preparing acetylated starch microspheres by nanoprecipitation, we studied the influencing factors of morphology, size and monodiepersity of the microspheres, including the ratio of deionized water, the preparation temperature, molecular weight, and the concentration of acetylated starch. The results showed that the proportion of water had significant effect on microsphere morphology and monodispersity. When the Vwatei:Vacetone was1:2, monodisperse acetylated starch nanospheres could be prepared. The size of the microspheres increased with increasing concentration, and decreased with increasing molecular weight. The molecular weight was higher by two orders of magnitude, the size of microspheres decreased by about100nm. The particle size and polydispersity of nanospheres in aqueous solution were measured by dynamic light scattering, The appearance of nanospheres was characterized by scanning electron microscopy (SEM).