Nanoscale metal-organic frameworks for drug delivery: a conventional platform with new promise

Development of a controllable drug delivery system is imperative and important to reduce the side-effects and enhance the therapeutic efficacy of drugs. Metal-organic frameworks (MOFs) and nanoscale MOFs (NMOFs), as porous hybrids constructed by polydentate bridging ligands and metal-connecting nodes, have attracted significant attention from the scientific community due to their tailorable compositions and structures, excellent porosity, and easier surface modification. Significant progress has been achieved in the past decade, but most attempts still remain in the proof-of-concept stage. This review highlights the latest advances in NMOFs for drug delivery systems and classifies the current drug-loading method into three strategies according to the location of the cargos and cargo-carrier interactions: encapsulation strategy, direct assembly strategy, and post-synthesis strategy. Each feature and the latest advances in these strategies are highlighted. Finally, the challenges and future perspectives in this field have been discussed.