Synthesis, Characterization and Application of Zeolitic Imidazole Framework-Mesoporous Silica Nanospheres Composite: A Hybrid Porous Composite for Drug Delivery

Abstract

Drug delivery system composed of mesoporous silica nanoparticles suffers from many drawbacks. Out of many challenges, two major challenges in drug delivery through mesoporous silica nanoparticles, are premature leakage and fast release of the drug molecules. Because of these, most of the time, efficiency of the drug delivery system become very low. In this work, mesoporous silica nanoparticles (MSN) have been modified using zeolitic imidazole framework through formation of a hybrid system. An anticancer drug Doxorubicin was encapsulated in mesoporous silica nanoparticles. Two zeolitic imidazole frameworks, ZIF-7 and ZIF-8 were prepared and used to form composite with mesoporous silica nanoparticles. The composites were characterized using scanning electron microscope, confocal laser scanning microscope, bright field imaging, powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis. BET surface analysis was conducted to understand the pore size, pore volume and surface area of the composite materials. The drug delivery study was conducted under pH stimuli as well as in present of liposome. The bare MSN were found to release the drug within 2-3 hours at pH∼4 and in presence of liposome. But both the composites were found to control the drug release over a period of 12 hours at pH∼4 and over a period of 7 hours in presence of liposome, which are almost 4 times slower release than bare mesoporous silica nanoparticles. This indicates that composite system has enough control on the drug release over the conventional drug delivery through bare mesoporous silica nanoparticles. This phenomenon was explained based on that, the ZIF frameworks act as a shield against the external stimuli and protects the bare silica from contact with the external agent and results in slower drug release. But in case of bare silica due to the absence of this kind of protection, drug release becomes very fast under acidic conditions.