Optimizing ibuprofen concentration for rapid pharmacokinetics on biocompatible zinc-based MOF-74 and UTSA-74.

Abstract

Metal-organic frameworks (MOFs) have potential as drug carriers on the basis of their surface areas and pore volumes that allow for high loading and fast release. This study investigated two biocompatible MOFs - Zn MOF-74 and UTSA-74 - for ibuprofen delivery. The effect of drug loading was studied by impregnating the MOFs with 30, 50, and 80wt% ibuprofen. The samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and N2 physisorption. From SEM, the MOF structures were maintained at 30wt% ibuprofen, however, became agglomerated at 50-80wt% loading, as the drug deposited on the surface and adhered the particles to one another. In the physisorption measurements, the Zn MOF-74 samples decreased in surface area with ibuprofen loading, until they became zero at 80wt%. In UTSA-74, the drug impregnation was less effective, as 35% of the original surface area was retained in the 80wt% sample. On the basis of our drug release measurements, 50wt% ibuprofen loading was found to be optimal on Zn MOF-74, as it gave rise to fast kinetics (k=0.27h-1/2) and high drug concentrations within the first 10h. In UTSA-74, the fastest release rate was observed at 30wt% loading (k=0.22h-1/2), as the poor impregnation efficiency blocked diffusion through the MOF pores at higher loading. Color changes of phosphate buffer saline (PBS) solutions at different time intervals also suggested that Zn MOF-74 decomposed during drug release, as it produced yellowing of the PBS solution. On the other hand, UTSA-74 did not discolor the PBS solution, and was concluded to not have dissolved during drug release. From these results, it was concluded that Zn MOF-74 was the superior drug carrier, as it could effectively deliver higher ibuprofen loadings and would dissolve in the process of drug release, thereby reducing its invasiveness in the human body.