Effect of a nano-sized natural clinoptilolite modified by the hexadecyltrimethyl ammonium surfactant on cephalexin drug delivery

The use of porous materials as host systems for medical applications has been considered in recent years. The aim of this work is to construct an efficient adsorbent for the adsorption and delivering of cephalexin. For this pupose, pretreated natural nano-sized clinoptilolite (NZ) was modified by the cationic hexadecyltrimethyl ammonium surfactant (HDTMA), and the obtained modified zeolite nanoparticles (SMZ) were used to design systems for storage and release of cephalexin (CPX). The adsorbed and released extents of the drug onto/from the modified zeolite were determined by UV–Vis spectroscopy. The results showed that both decreasing the particle size of clinoptilolite and modifying its surface significantly increase the adsorbed drug extent. All the compounds were characterized by SEM, TEM, FT–IR, TG/DTG, and XRD. TG/DTG and also FT–IR results showed sufficient loading amounts of HDTMA and CPX onto the raw and modified zeolite, respectively. It was proven by means of TG that the composites are more stable thermally when the admicelles contain cephalexin in their interior. IR spectroscopy studies indicated that the zeolite structure remained unchanged after the modification with the surfactant and after the cephalexin drug has been loaded. Due to the presence of hydroxyl and amine groups in the cephalexin structure, pH plays an important role on the adsorbed CPX extent, so that the maximum adsorbed CPX was observed at pH = 12. While the delivery of CPX was better at pH = 2, because at alkaline pHs, the anionic carboxylate form of CPX has higher attractive force with the positive head of the surfactant on the SMZ. Hence, the stomach's acidic pH is appropriate for drug delivery. The effects of some cations in the delivery extent confirm that the diet can significantly affect the delivery of the CPX from the proposed adsorbent.