Two biocompatible iron-based CPMs for high-capacity adsorption and pH-responsive sustained release of diclofenac sodium

The development of a pharmaceutical drug delivery system (DDS) faces two problems: low drug capacity and poor biodegradability. This study focused on synthesizing two iron-based crystalline porous materials (CPMs) with a cationic framework and their loading capacities and sustained release behavior for diclofenac sodium (DS), an anionic drug. The moderate hierarchical structures and the positively charged frameworks confer upon the two compounds an exceptionally high adsorption capacity for DS under electrostatic attraction, with drug loadings reaching 36.92 and 68.55 wt%, respectively. As for the DS sustained release behavior, the whole process lasted up to 96 hours in both of the two CPM drug carriers, considerably prolonging the release time of DS, which helped reduce blood drug concentration and drug toxicity. In addition, the drug delivery system DS@Fe-CPM-1 in the gastric juice (pH = 1.5) exhibited a more effective release, while DS@Fe-CPM-2 showed excellent delivery in normal tissues (pH = 7.4), indicating that they can be used in different physiological surroundings according to intrinsic pH-responsive behavior. The cytotoxicity test demonstrated that both the iron-based crystalline materials were biocompatible, which is critical to developing new drug delivery systems in the future.