Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale, Università di Napoli Federico II, Piazzale V. Tecchio 80, 80125 Napoli, Italy.
DiSTAR, Università di Napoli Federico II, Via Mezzocannone 8, 80134 Naples, Italy.
Colloids Surf B Biointerfaces. 2015 Jun 1;130:101-9. doi: 10.1016/j.colsurfb.2015.03.052. Epub 2015 Apr 3.
In view of zeolite potentiality as a carrier for sustained drug release, a clinoptilolite-rich rock from California (CLI_CA) was superficially modified with cetylpyridinium chloride and loaded with diclofenac sodium (DS). The obtained surface modified natural zeolites (SMNZ) were characterized by confocal scanning laser microscopy (CLSM), powder X-ray diffraction (XRPD) and laser light scattering (LS). Their flowability properties, drug adsorption and in vitro release kinetics in simulated intestinal fluid (SIF) were also investigated. CLI_CA is a Na- and K-rich clinoptilolite with a cationic exchange ability that fits well with its zeolite content (clinoptilolite=80 wt%); the external cationic exchange capacity is independent of the cationic surfactant used. LS and CLSM analyses have shown a wide distribution of volume diameters of SMNZ particles that, along with their irregular shape, make them cohesive with scarce flow properties. CLSM observation has revealed the localization of different molecules in/on SMNZ by virtue of their chemical nature. In particular, cationic and polar probes prevalently localize in SMNZ bulk, whereas anionic probes preferentially arrange themselves on SMNZ surface and the loading of a nonpolar molecule in/on SMNZ is discouraged. The adsorption rate of DS onto SMNZ was shown by different kinetic models highlighting the fact that DS adsorption is a pseudo-second order reaction and that the diffusion through the boundary layer is the rate-controlling step of the process. DS release in an ionic medium, such as SIF, can be sustained for about 5h through a mechanism prevalently governed by anionic exchange with a rapid final phase.
鉴于沸石作为缓释药物载体的潜力，对来自加利福尼亚的富含斜发沸石的岩石（CLI_CA）进行了十六烷基氯化吡啶的表面改性，并负载了双氯芬酸钠（DS）。通过共焦扫描激光显微镜（CLSM）、粉末 X 射线衍射（XRPD）和激光光散射（LS）对所得的表面改性天然沸石（SMNZ）进行了表征。还研究了它们在模拟肠液（SIF）中的流动性、药物吸附和体外释放动力学。CLI_CA 是一种富含 Na 和 K 的斜发沸石，具有与其沸石含量（斜发沸石=80wt%）相匹配的阳离子交换能力；外部阳离子交换能力与所用阳离子表面活性剂无关。LS 和 CLSM 分析表明 SMNZ 颗粒的体积直径分布很广，其不规则的形状使得它们具有粘性，流动性较差。CLSM 观察表明，不同分子根据其化学性质在 SMNZ 中/上定位。特别是，阳离子和极性探针优先定位在 SMNZ 体相中，而阴离子探针则优先排列在 SMNZ 表面上，并且不鼓励非极性分子在 SMNZ 中/上的装载。通过不同的动力学模型显示了 DS 对 SMNZ 的吸附速率，突出表明 DS 吸附是一个准二级反应，并且通过边界层的扩散是该过程的速率控制步骤。在离子介质（如 SIF）中，DS 的释放可以通过阴离子交换机制持续约 5 小时，该机制主要由阴离子交换控制，最后阶段迅速进行。
