Performance of MIL-101(Cr) and MIL-101(Cr)-Pore Expanded as Drug Carriers for Ibuprofen and 5-Fluorouracil Delivery

Metal-organic frameworks (MOFs) have been extensively investigated as nanocarriers for drug delivery applications owing to their remarkable surface area and porosity, which allow for impregnation of large quantities of drugs with fast pharmacokinetics. In this work, we developed a pore-expanded version of MIL-101(Cr), MIL-101(Cr)-P, and assessed its potential as a carrier for ibuprofen and 5-fluorouracil drugs along with its regular MIL-101(Cr) analogue. The pore expansion strategy gave rise to a higher surface area and mesopore volume for MIL-101(Cr)-P relative to regular MIL-101(Cr). The characterization results revealed successful incorporation of 30, 50, and 80 wt % of both drugs within the MOF structure. Upon incorporation of species, the surface area and porosity of the two MOF carriers decreased drastically; however, the drug-loaded MOFs still retained some degree of porosity, even at high drug loadings. For both drugs, the delivery experiments conducted in phosphate-buffered saline (PBS) showed that MIL-101(Cr)-P possessed better pharmacokinetic behavior than MIL-101(Cr) by delivering higher amounts of drug at all three loadings and exhibiting much faster release rates. Such behavior was originated from large mesopores that were created during pore expansion, providing diffusional pathways for efficient delivery of the drugs. The highest rate constant obtained by fitting the release kinetics to the Higuchi model was found to be 0.44 h^-1/2 for the release of 30 wt % 5-fluorouracil from MIL-101(Cr)-P. The findings of this study highlight the role of tuning physiochemical properties of MOFs in improving their pharmacokinetic behavior as drug carriers.