As a result of their extraordinarily large surfaces and well-defined pores, the design of a multifunctional metal-organic framework (MOF) is crucial for drug delivery but has rarely been reported. In this paper, a novel drug delivery system (DDS) based on nanoscale MOF was developed for use in cancer diagnosis and therapy. This MOF-based tumor targeting DDS was fabricated by a simple postsynthetic surface modification process. First, magnetic mesoporous nanomaterial Fe-MIL-53-NH was used for encapsulating the drug and served as a magnetic resonance contrast agent. Moreover, the Fe-MIL-53-NH nanomaterial exhibited a high loading capacity for the model anticancer drug 5-fluorouracil (5-FU). Subsequently, the fluorescence imaging agent 5-carboxyfluorescein (5-FAM) and the targeting reagent folic acid (FA) were conjugated to the 5-FU-loaded Fe-MIL-53-NH, resulting in the advanced DDS Fe-MIL-53-NH-FA-5-FAM/5-FU. Owing to the multifunctional surface modification, the obtained DDS Fe-MIL-53-NH-FA-5-FAM/5-FU shows good biocompatibility, tumor enhanced cellular uptake, strong cancer cell growth inhibitory effect, excellent fluorescence imaging, and outstanding magnetic resonance imaging capability. Taken together, this study integrates diagnostic and treatment aspects into a single platform by a simple and efficient strategy, aiming for facilitating new possibilities for MOF use for multifunctional drug delivery.

An amazing millimeter-sized lanthanide metal–organic framework, Tb-MOF, was synthesized. Due to the larger volume, Pb2+ ions can be sensitively and selectively detected by visible fluorescence quenching of Tb-MOF. Additionally, a Tb-MOF crystal film with an ultra-high recognition ability of Pb2+ ions has been fabricated successfully.

An advanced multifunctional, hollow metal-organic framework (MOF) drug delivery system with a high drug loading level and targeted delivery was designed and fabricated for the first time and applied to inhibit tumour cell growth. This hollow MOF targeting drug delivery system was prepared via a simple post-synthetic surface modification procedure, starting from hollow ZIF-8 successfully obtained for the first time via a mild phase transformation under solvothermal conditions. As a result, the hollow ZIF-8 exhibits a higher loading capacity for the model anticancer drug 5-fluorouracil (5-FU). Subsequently, 5-FU-loaded ZIF-8 was encapsulated into polymer layers (FA-CHI-5-FAM) with three components: a chitosan (CHI) backbone, the imaging agent 5-carboxyfluorescein (5-FAM), and the targeting reagent folic acid (FA). Thus, an advanced drug delivery system, ZIF-8/5-FU@FA-CHI-5-FAM, was fabricated. A cell imaging assay demonstrated that ZIF-8/5-FU@FA-CHI-5-FAM could target and be taken up by MGC-803 cells. Furthermore, the as-prepared ZIF-8/5-FU@FA-CHI-5-FAM exhibited stronger cell growth inhibitory effects on MGC-803 cells because of the release of 5-FU, as confirmed by a cell viability assay. In addition, a drug release experiment in vitro indicated that ZIF-8/5-FU@FA-CHI-5-FAM exhibited high loading capacity (51%) and a sustained drug release behaviour. Therefore, ZIF-8/5-FU@FA-CHI-5-FAM could provide targeted drug transportation, imaging tracking and localized sustained release.

Benefiting from their porous structures, metal-organic frameworks (MOFs) have attracted intensive attention for use in drug release. However, the controllable synthesis of MOFs with proper particle sizes is still very challenging, which largely limits its applications. Here, UIO-66-NH2 with controlled particle sizes in the range of 20-200 nm has been achieved successfully. The amine on UIO-66-NH2 is demonstrated for the feasible post-modifying of UIO-66-NH2 to obtain multifunctional MOFs, overcoming the limitations of functional simplicity and broadening the range of applications. After covalent grafting the targeting reagent folic acid (FA) and the fluorescence imaging agent 5-carboxyfluorescein (5-FAM), UIO-66-NH2-FA-5-FAM/5-FU can target the cancer cells HePG-2 and display excellent fluorescence imaging in vitro. Moreover, the in vivo biodistribution and antitumor assays indicate that UIO-66-NH2-FA-5-FAM/5-FU can accumulate in the tumor and display stronger antitumor efficiency due to the long-time drug release. Taken together, this study integrates the imaging section and the treated section in a single platform successfully and the present approach can be a good use of therapeutic MOFs to achieve the desired objective, a better treatment.

A one-pot process has been developed for the synthesis of hierarchical-pore metal–organic frameworks, aimed at loading large and small drug molecules simultaneously.