pH响应性PAA/毒死蜱/氨基化介孔硅缓释体系的制备与性能

以共缩聚法合成氨基化介孔硅，采用浸渍法制备毒死蜱/氨基化介孔硅，并以带负电荷的聚丙烯酸（PAA）为功能分子，通过静电吸附作用制备了具有pH响应的PAA/毒死蜱/氨基化介孔硅缓释体系。利用XRD、N₂吸附-脱附、TEM、SEM、TG、Zeta电位和FTIR对PAA/毒死蜱/氨基化介孔硅的结构进行了表征，并探究了其在不同pH和温度下的释药行为。结果表明，PAA通过静电作用包覆于毒死蜱/氨基化介孔硅的表面。缓释体系的药物释放主要受到PAA的阻碍作用，PAA修饰载药氨基化介孔硅显示出明显的pH响应性，当pH≤7时，其药物释放速率随pH减小而增大，而在偏碱性条件下的释药速率稍大于中性环境。同时，载药体系的释药速率还受到温度的影响。其释药行为可用Korsmeryer-Pappas动力学模型来描述。

Preparation and properties of pH-responsive control release system of PAA/chlorpyrifos/amino functionalized mesoporous silica

A pH-responsive control release system of PAA/chlorpyrifos/mesoporous silica was prepared by using negative charged polyacrylic acid (PAA) to encapsulate amino functionalized mesoporous silica (NH₂-MCM-41) with chlorpyrifos loaded in the pores. The PAA/chlorpyrifos/NH₂-MCM-41 system were systematically characterized using X-ray diffraction (XRD), N₂ adsorption-desorption, transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Zeta potential and Fourier transform infrared spectroscopy (FTIR). The release behavior of chlorpyrifos was studied at various pH and temperature conditions. The experimental results showed that PAA was coated on the surface of chlorpyrifos/amino functionalized mesoporous silica as a result of electrostatic interaction. The chlorpyrifos release from the PAA/chlorpyrifos/NH₂-MCM-41 system was inhibited mainly by PAA blockage with significant pH sensitivity, which increased with pH decrease at pH ≤ 7 and was slightly higher in weak base condition than that in neutral condition. The release also exhibited some temperature dependence and generally followed the Korsmeyer-Peppas kinetic model.