Degradation and Erosion of Metal–Organic Frameworks: Comparative Study of a NanoMIL-100 Drug Delivery System
Résumé
To make a drug work better, the active substance can be incorporated into a vehicle for optimal protection and control of drug delivery time and space. For making the drug carrier, the porous metal-organic framework (MOF) can offer high drug loading capacity, various designs for effective drug delivery performance, biocompatibility, and biodegradability. Nevertheless, its degradation process is complex and not easily predictable, and the toxicity concern related to the MOF degradation products remains a challenge for their clinical translation. Here, we describe an in-depth molecular and nanoscale degradation mechanism of aluminum- and iron-based nanoMIL-100 materials exposed to phosphate buffer saline (PBS). Using a combination of analytical tools, including X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR) spectroscopy, small-angle X-ray scattering (SAXS), and electron microscopy, we demonstrate qualitatively and quantitatively the formation of new coordination bond between metal(III) and phosphate, trimesate release, and correlation between these two processes. Moreover, the extent of material erosion, i.e., bulk or surface erosion, was examined from the transformation of nanoparticles' surface, morphology, and interaction with water. Similar analyses show the impact of drug loading and surface coating on nanoMIL-100 degradation and drug release as a function of metal-ligand binding strength. Our results indicate how the chemistry of nanoMIL-100(Al) and nanoMIL-100(Fe) drug carriers affect their degradation behaviors in a simulated physiological medium. This difference in behavior between the two nanoMIL-100s enables us to correlate better the nanoscale and atomic scale mechanisms of the observed phenomena, thus validating the presented multi-scale approach.
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