Novel MOF/aerogel composites ((MOFACs) for drug delivery purposes

Composites of MOFs and aerogels (MOFACs) are a new class of nanostructured materials attracting increasing attention due to their favorable properties. The combination of micro-/mesoporosities of MOFs with meso-/macroporosities of aerogels makes MOFACs hierarchically multimodal porous materials. MOFACs with their high surface areas, combined morphological, mechanical, physicochemical and functional properties of both MOFs and aerogels have demonstrated outstanding performances in various applications. In the field of drug delivery, MOFs and aerogels have both been investigated extensively. Combining bimodal porosity and functionality of both MOFs and aerogels is a promising area for drug delivery applications. In this study, novel Metal-Organic Frameworks/Aerogel composites (MOFACs) comprised of different types of MOFs (Fe-BTC, ZIF-8 or UiO-66) and calcium alginate were synthesized. Spherical bead shaped composites were obtained by incorporating microporous MOFs into meso- and macroporous aerogel matrix by simple mixing combined with dripping technique. The composites were characterized with nitrogen sorption, XRD, SEM and FTIR. The nitrogen adsorption study showed that the MOFACs synthesized had achieved hierarchically macro-, meso- and micro porosities and MOFs micropores were open and accessible. XRD analysis revealed that the MOFs were intact and in crystalline form. FTIR study showed that the MOF and alginate matrix formed a physical mixture in the composite. The synthesized composites were further loaded with two different drugs paracetamol (acetaminophen) or ibuprofen. Paracetamol was loaded from ethanolic solutions via SAS (supercritical antisolvent precipitation) inside the pores whereas ibuprofen was loaded from supercritical CO2 solutions. The factors that affect the loading amount and distribution of the drug inside the composite matrix were investigated. Paracetamol loadings were found to be highly dependent on and limited by the drug concentration in ethanolic loading solutions as well as having excess solutions in the extraction vessel prior to supercritical drying. Almost 70 wt% paracetamol loadings were achieved with 1.2 M loading solutions and having excess solutions. Around 20 wt% ibuprofen loadings were achieved from supercritical CO2 solutions. The release behavior of the drugs from the composite matrices to PBS buffer or distilled water were investigated. It was shown that the Fe-BTC/Alginate composites were promising for paracetamol delivery and ZIF-8/Alginate composites were found to be promising for ibuprofen delivery as both systems achieved delayed drug delivery with increasing amounts of MOF content in the composites. Lastly, all release kinetics were fitted into Korsmeyer-Peppas model. It was found that Fickian diffusion is the main transport mechanism while some PBS systems with excess solutions also showed swelling behavior.