In this paper, new porous pH-responsive microspheres based on functionalized halloysite nanotubes (HNTs) with poly-lactic-co-glycolic acid (PLGA) are investigated as the phenytoin sodium (PHT-Na) carrier. For this purpose, the surfaces of HNTs were modified by a silane coupling agent, (3-aminopropyl)triethoxysilane (APTES) and then the desired microsphere was synthesized through PLGA coating on modified HNTs. Formation of these hybrid particles are confirmed using various characterization methods like Fourier transform infrared (FT-IR), transmission electron microscope (TEM), scanning electron microscope (SEM), EDX, zeta-potential, and X-ray diffraction. The results of the FT-IR spectrum show the presence of APTES, PHT-Na and PLGA peaks, which supported the modification of HNTs and drug capsulation. TEM images confirm the presence of APTES on HNTs, due to the increase in outer diameter. SEM images displayed that by grafting PLGA polymer to modified HNTs, the shape of nanotubes has changed from rod-like to microsphere. Hence, the prospering connection of APTES and PLGA on HNTs was emphasized by zeta-potential results. Moreover, the profile of drug release is recorded via HPLC. In vitro drug release tests show that both the presence of polymer chains around drug containers and the pH value of the release medium play an important role in controlled release. Eventually, the kinetics of drug release was evaluated based on Korsmeyer–Peppas kinetic model.

中文翻译：

---

苯妥英钠控释的可生物降解pH响应性埃洛石聚乳酸-乙醇酸微球的制备与表征

在本文中，基于官能化高岭土纳米管（HNTS）用聚乳酸-新多孔pH响应性微球共研究了乙醇酸（PLGA）作为苯妥英钠（PHT-Na）的载体。为此，用硅烷偶联剂（3-氨基丙基）三乙氧基硅烷（APTES）对HNT的表面进行改性，然后通过PLGA涂覆在改性HNT上合成所需的微球。这些杂化粒子的形成使用多种表征方法来确认，例如傅立叶变换红外（FT-IR），透射电子显微镜（TEM），扫描电子显微镜（SEM），EDX，ζ电位和X射线衍射。FT-IR光谱结果显示APTES，PHT-Na和PLGA峰的存在，这支持了HNT的修饰和药物封壳。TEM图像确认HNT上存在APTES，这是由于外径增加所致。SEM图像显示，通过将PLGA聚合物接枝到改性的HNT上，纳米管的形状已从棒状变为微球状。因此，ζ电位结果强调了APTES和PLGA在HNT上的繁荣联系。此外，药物释放曲线通过HPLC记录。体外药物释放测试表明，药物容器周围的聚合物链的存在和释放介质的pH值在控制释放中均起着重要作用。最终，基于Korsmeyer-Peppas动力学模型评估了药物释放的动力学。体外药物释放测试表明，药物容器周围的聚合物链的存在和释放介质的pH值在控制释放中均起着重要作用。最终，基于Korsmeyer-Peppas动力学模型评估了药物释放的动力学。体外药物释放测试表明，药物容器周围的聚合物链的存在和释放介质的pH值在控制释放中均起着重要作用。最终，基于Korsmeyer-Peppas动力学模型评估了药物释放的动力学。