(602f) A Generalizable Approach to Synthesize Polymer-Metal-Organic Framework Gels for Drug Delivery

Biomaterials that extend and control the release of drug molecules are useful for therapeutic applications such as wound healing. Hydrogels are a class of biomaterials that can serve as drug delivery depots for biologics like peptides and proteins. However, hydrogels suffer from poor loading capacity (10-200 mg/g) and fast release times (a few hours to a day). On the other hand, metal-organic frameworks (MOFs), composed of inorganic metal clusters and organic linkers, have demonstrated exceptionally high drug loading capacity (0.15-1.0 g/g) and extended-release (a few days to a week) due to their large specific surface area (1000-6000 m²/g) and tunable pore sizes (5 Ã… – 40 Ã…). Nonetheless, the minimal hydrophilicity of MOFs results in the poor solubility of MOFs in an aqueous medium thus limiting their biomedical applications. Combining MOFs and polymers to create polymer-MOF gels may overcome the limitations of both polymers and MOFs. To date, limited research has been done on the synthesis and properties of polymer-MOF gels and a generalizable way to prepare polymer-MOF gels is still unknown. We approach this problem by understanding the formation mechanism of polymer-MOF gels. We hypothesize that introduction of chemical interactions between MOF and polymer would result in polymer chains cross-linked by MOF particles thus rendering gel structures. We test this hypothesis using poly(vinyl alcohol) (PVA) which interacts with metal clusters through hydrogen bonding. We prepare a solution of PVA and organic linker followed by the addition of metal cluster solution which results in a self-standing gel at room temperature after 24 h. We confirm the formation of MOF particles in gel using X-ray diffraction and transmission electron microscopy. Additionally, we synthesize polymer-MOF gels using PVA and 4 different MOFs thus demonstrating the generalizability of the synthesis process. To demonstrate the utility of gels for drug delivery in an aqueous medium, we show the release of small drug molecules for up to 2 weeks from polymer-MOF gels. The synthesis protocol developed here can be extended to a variety of polymers and MOFs to create a library of polymer-MOF gels for studying the release of peptides and proteins.