Metal-organic frameworks for drug delivery: Degradation mechanism and in vivo fate

Abstract Metal-organic frameworks (MOFs) are a novel class of hybrid materials formed by the self-assembly of metal centers and bridging organic ligands. They attract growing interest for drug delivery in reason of their versatile structures, biodegradability, and lack of toxicity. Nowadays, MOFs are used in a variety of biomedical applications as drug carriers and contrast agents. They are also suitable for theranostics, the personalized treatment combining drug targeting and imaging. One major prerequisite for the use of MOFs in biomedicine is their biodegradability and biocompatibility after administration in the living organism. For this reason, it is of outmost importance to have a deep understanding of both the stability and the degradation patterns of the porous MOF materials, as well as of their fate after degradation (nature of the degradation products and their excretion). For in vivo applications, engineered core-shell MOFs are produced and it was demonstrated that both the cores hosting the drugs and the shells influenced degradation and drug release. This chapter overviews the degradation mechanism of biodegradable MOFs, based on recent in vitro, and more importantly, in vivo studies, in different media and animal models.