Synthesis and characterization of MFI-type borosilicate zeolites and evaluation of their efficiency as drug delivery systems.

MFI-type borosilicate zeolites with different Si/B ratio were synthesized by hydrothermal method using silicic acid and sodium tetraborate decahydrate as starting materials. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry analysis (TGA/DTG) and Fourier transform infrared spectroscopy (FT-IR). Different characterization techniques confirmed the incorporation of boron atoms into the zeolite framework. SEM images revealed that the particle size of zeolites and their morphology can be controlled by different synthesis parameters. The effect of different parameters such as crystallization time and temperature, pH value of initial gel and Si/B ratio on the crystallinity, morphology and incorporation of boron atoms into final products was investigated and discussed in detail. The efficiency of synthesized borosilicate zeolites as drug delivery systems was examined by loading and in vitro release of anticancer drug doxorubicin (DOX). The results demonstrated that DOX-loaded borosilicate samples show a pH-sensitive drug release feature with higher drug release rate in relatively lower pH values. In vitro cytotoxicity of DOX- loaded borosilicate was evaluated by MTT assay.