Zeolitic Imidazole Framework (ZIF) Nanospheres for Easy Encapsulation and Controlled Release of an Anticancer Drug Doxorubicin under Different External Stimuli: A Way toward Smart Drug Delivery System

The conventional drug delivery systems made from organic- or inorganic-based materials suffer from some problems associated with uncontrolled drug release, biocompatibility, cytotoxicity, and so forth. To overcome these problems, zeolitic imidazole framework (ZIF) hybrid materials can be one of the solutions. Here, we report a very easy and successful encapsulation of an anticancer drug doxorubicin inside two ZIFs, namely, ZIF-7 and ZIF-8, which are little explored as drug delivery systems, and we studied the controlled release of the drug from these two ZIFs under external stimuli such as change in pH and upon contact with biomimetic systems. Experimental results demonstrate that ZIF-7 remains intact when the pH changes from physiological condition to acidic condition, whereas ZIF-8 successfully releases drug under acidic condition. Interestingly, both the ZIFs are excellent for drug release when they come in contact with micelles or liposomes. In the case of ZIF-8, the drug delivery can be controlled for 3 h, whereas its analogue ZIF-7 delivers the drug for a time span of 10 h. We explained the reluctance of ZIF-7 toward drug release in terms of rigidity. This study highlights that by using different ZIFs and liposomes, the drug release rate can be easily modulated, which implies ample possibility for ZIFs as a good drug delivery system. The study shows a novel strategy for easy drug encapsulation and its release in a controlled manner, which will help future development of the drug delivery system.