Final Report Summary - BIOMOF (Biomineral-inspired growth and processing of metal-organic frameworks) The BIOMOF project outlines a strategy for the growth and processing of porous metal-organic framework (MOF) materials inspired by the interfacial interactions that are typical of highly controlled natural biomineralisation processes. MOFs are hybrid network structures formed by the self-assembly of metal ions and multifunctional organic linking groups and have myriad applications in catalysis, drug delivery, molecular separation and storage which is readily enhanced by processing into composites and other application-specific configurations. The BIOMOF project involves the development of new synthetic growth and processing protocols using well known MOFs and we have successfully demonstrated that the concepts of biomineralisation can be readily applied for the formation of MOF@polymer, MOF@oxide and MOF@biopolymer composites using both soft and hard functional interfaces and colloidal assembly strategies. The composite materials prepared have enhanced properties over their individual components for use in challenging separations, controlled delivery and catalysis. For example, we have demonstrated that the deposition of MOFs onto hierarchically structured silica particles results in a novel separation media for enhanced xylene separation, and the promotion of MOF surface etching resulting from our supramolecular templating strategy can further reduce column back pressures. A major outcome of the work has been the colloidal assembly of preformed MOF particles around emulsion droplets to prepare new classes of MOF and MOF-polymer composite microcapsules displaying size-selective and on demand release of encapsulated molecules. By loading magnetic MOF microcapsules with enzymes, a recyclable size-selective biocatalyst with enhanced activity was also successfully prepared.Using a soft biopolymer interface such as non-toxic gelatin, we can successfully grow MOFs within a hydrogel matrix. This allows us to tune MOF particle size and prepare highly stable colloidal dispersions in water, which are vital if MOFs are to be used for biomedical applications. While the gelatin undoubtedly increases MOF biocompatibility, it also allows us to form the MOF particles using otherwise incompatible reaction conditions and with unexpected crystal shapes. This is directly analogous to matrix-mediated biomineralisation processes where soft organic boundaries seal off mineralisation compartments from the external environment and regulate the chemistry within to promote deposition and control particle size and shape demonstrating that biomineralisation strategies are applicable to MOF networks.The controlled and selective deposition of MOFs to form thin films is well developed, but it remains challenging to do this on 3-dimensional objects. To address this issue we have employed bipolar electrochemical deposition techniques to MOFs, where conducting metal substrates can be selectively coated by MOF crystals. This is a simple and scalable technique relevant to a large number of MOFs, allowing the facile preparation of metal@MOF composites.Finally, as part of our studies at the MOF-biology interface, we have recently demonstrated that monodisperse amorphous MOF nanospheres prepared under dilute aqueous conditions can be internalised by brain endothelial cells and efficiently release their cargo to these cells. This is significant as brain disorders continue to exert a major societal and economic strain as ageing populations continue to grow. New nano-delivery systems thus have enormous potential to enhance treatment of neurological disorders and it is clear from our work that MOFs have a role to play in this.Overall, BIOMOF was very successful and provides a clear indication that MOF properties can be enhanced by appropriate configuration or through composite formation. This will continue to increase the relevance and extend the reach of these exciting microporous materials into hitherto unexplored areas of materials science and applications.
