One-pot synthesis of hierarchical-pore metal-organic frameworks for drug delivery and fluorescent imaging

Metal-organic frameworks (MOFs) have attracted significant interest for drug delivery. However, MOFs usually have micropores smaller than 2 nm, restraining larger drug molecules from entering into the pores of MOFs, restricting their practical application as drug carriers. Here we demonstrate a novel one-step approach to synthesize a fluorescent hierarchical-pore metal-organic framework (H-MOF), which is realized by assembling a MOF in an aqueous solution containing rhodamine b (RhB) as a modulator and a fluorescent imaging reagent. The as-synthesized fluorescent H-MOF can not only serve as a substrate to in situ load micromolecule and macromolecular drugs simultaneously, but can also efficiently deliver the drugs into cells. The red fluorescence of RhB remains in the H-MOF, avoiding the interference of auto-fluorescence in vivo imaging and realizing high quantum yield and low-background imaging. The low cytotoxicity, good biocompatibility and high imaging efficiency of the fluorescence H-MOF are confirmed using murine gastric cancer 803 (MGC-803) cells and human airway smooth muscle cell (HASMC) as modes. Good stability and distribution in vivo are confirmed using naked mouse as modes. Taken together, we demonstrate the possibility of using one-step method to obtain fluorescent H-MOF, aiming for loading various drug molecules and bioimaging, which probably is useful for some specific requirements of pharmaceuticals.