Porous metal–organic framework nanoscale carriers as a potential platform for drug delivery

Metal–organic framework (MOF) is a class of well-ordered and crystalline porous coordination polymers. Research on advanced MOFs such as polymer-based MOFs and nanoparticle-based MOFs have been explored to a great extent in biomedical applications, especially in drug delivery systems. Nano-MOFs have been investigated and proved to be very effective for in vivo and in vitro drug delivery. Because nano-MOFs have a larger surface area, porous nature, tunable structure, and composition, they are intensely desirable in drug delivery. MOFs are classified according to their metals (Cu, Fe, Zr, Zn, and K) and organic frameworks. The functionalization of MOFs is accomplished through surface adsorption, covalent binding, and pore encapsulation. The efficiency of nano-MOFs in drug delivery is evaluated by their pharmacokinetic characteristics, including toxicity level, biosafety, ease of removal after drug delivery, and their bioavailability. The bioavailability of drug-loaded MOFs depends on mucosal penetration, gastric pH, metabolic enzymes, and physicochemical properties.