谷氨酸插层水滑石组装、包裹及缓释性能研究

采用共沉淀法和离子交换法实现了谷氨酸与Zn/Al水滑石的插层组装,并采用X射线粉末衍射、差热分析、红外光谱表征了谷氨酸插层水滑石的结构,并在模拟胃液和肠液中测试了复合材料中谷氨酸的缓释性能。结果表明,合成的水滑石前躯体（LDHs-NO3）结构规整、晶相单一,层间距为0.879 nm;2种方法合成的谷氨酸插层水滑石,其层间距分别增加到1.251 nm和1.334 nm,可以推测谷氨酸以垂直方式分布于水滑石层间。插层后水滑石样品在1588 cm-1和1346 cm-1处出现了谷氨酸中羧酸根的不对称伸缩振动和对称伸缩振动峰,也佐证了氨基酸插层成功。谷氨酸插层水滑石后,其热稳定性大大提高,热分解温度由230℃升高至397～434℃。与物理混合法相比,谷氨酸与水滑石复合后增加了谷氨酸的耐酸性,使其具有较好的缓释性能。谷氨酸释放曲线符合Bhaskar方程,表明微粒间的扩散作用是谷氨酸分子释放的限速步骤。LDHs-Glu经海藻酸钠包裹后,在模拟肠液中缓慢释放而在模拟胃液中不释放,起到了肠液定向释放的效果。

Assembling,Coating and Slow-Release Properties of Glutamic Acid Intercalated Layered Double Hydroxide

Glutamic acid intercalated Zn/Al layered double hydroxides were realized with coprecipitation and ion-exchange method,and the structure was characterized by the X-ray powder diffraction,DTA,and FT-IR analysis.Slow-release performance of LDHs-Glu was tested in the simulated stomach and intestinal juice.The results show that the structure of synthetic hydrotalcite is regular,and crystal phase is single.When glutamic acid is intercalated into hydrotalcite,the interlayer spacing increases from 0.879 nm to 1.251-1.334 nm,so it is speculated that glutamic acid intercalated in the interlayer of hydrotalcite with the vertical form.The asymmetric vibration and symmetric vibrating peaks of carboxylic group of LDHs-Glu existed in 1588 and 1346 cm-1,which provided that glutamic acid is successfully intercalated.Thermal stability of amino acid has been greatly improved after intercalation,and thermo-decomposing temperature of glutamic acid rises from 230 to 397-434 ℃.Compared with physical mix method,the acidoresistant property of LDHs-Glu is promoted,and it has the obvious slow-release performance.Release curve accords with Bhaskar equation,which demonstrates that the diffusion of particles is the rate-determining step.After coating of sodium alginate,LDHs-Glu(coating) possesses the ability of a directional release effect,namely slow-release in the simulation of intestinal juice but not the release in the simulation gastric juice.