Our main goal was to evaluate release mechanism of microcapsules with different core status. First, flufiprole microcapsules were directly encapsulated with chitosan (CS) and sodium dodecyl sulfate (SDS) through layer-by-layer (LbL) self-assembly. The changes of process parameters on the microcapsules characteristics (zeta potential, and morphology) were investigated. Also the release trends of flufiprole were determined and fitted with mathematical models. It was revealed that releases of three types of microcapsules were all very similar, but microcapsule with solid particles and oil suspending agent reached their peak values at 36–42, 42–48 h respectively, microcapsule with solution droplets cannot reach a maximum value. In the stage of initial burst release, Higuchi model performed better with oil suspending agent and solid particles, which was in agreement with the Fick's law. Core status being solution, release curves of the pesticide corresponded to zero-order which was in agreement with dissolution mechanism. In the stage of slow release, the values of R2 for solution and solid particles were all above 0.98, betokened the release phenomenon were in line with the first-order. On the other hand, release of oil suspending agent conformed to Higuchi model.
In order to improve the water solubility and stability of curcumin (CUR) and achieve its sustained release, the ZEIN– N -(2-hydroxy) propyl-3-trimethylammonium chitosan chloride (HTCC) complexes were designed to encapsulate CUR using an antisolvent precipitation (ASP) method. The encapsulation efficiency ( EE ) and loading capacity ( LC ) of curcumin in ZEIN-HTCC complexes were 92.2% and 0.6%, respectively. After encapsulation, the resistance of curcumin to thermal, natural light and UV irradiation, as well as the antioxidative activity were improved significantly ( P < 0.05). ZEIN-HTCC-CUR complexes exhibited good redispersibility and enhanced the water solubility of curcumin. In vitro simulated digestion experiments clarified that the ZEIN-HTCC complexes can control the sustained release behavior of curcumin, and the release kinetics can be fitted by the Higuchi model. Results taken from fluorescence spectra and Fourier transform infrared spectroscopy (FTIR) indicated that hydrophobic interaction, hydrogen bonding and electrostatic interactions were the main driving forces to form the ZEIN-HTCC-CUR complexes. The X-ray diffraction (XRD) results revealed that the encapsulated curcumin was in an amorphous state. The information provided by this study should be of interest to food industry to fabricate robust nanoscale delivery systems with ZEIN-HTCC complexes for CUR and other hydrophobic bioactive compounds.
The porous rice starch (PS) and Xanthan gum (XG) are mixed at different ratios to embed the curcumin. The morphology and physicochemical properties of the microcapsules are characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC), and fourier transform infrared spectroscopy (FT-IR); the release of curcumin is evaluated with a simulated gastric-small intestine model. Results indicate that all the microcapsules present high encapsulation efficiency (>90%) with an average particle size of around 3.30 µm. The curcumin loaded in PS and PS/XG microcapsules forms inclusion complexes rather than simple physical mixtures. The release mechanism of curcumin from microcapsules fits first-order ( R 2 > 0.974) and Higuchi ( R 2 > 0.969) models well in gastric and intestinal models, respectively, indicating that encapsulation of curcumin within PS/XG enables controlled release of curcumin. PS/XG wall materials show great potential for encapsulation and delivery of curcumin.
危险品化学品经营许可证（带存储）