David Fairén-Jiménez, Royal Society University Research Fellow, University of Cambridge
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The building-block approach to the synthesis of metal-organic frameworks (MOFs) has opened the possibility to synthesise a virtually infinite number of these materials. This creates exciting opportunities, but also raise the question of how to identify and classify MOFs among the plethora of existing crystal structures. At the same time, experimental trial-and-error discovery of MOFs is not fast enough and therefore new methods accessible not only to computational researchers but mainly to experimentalists need to be developed.
To solve this problem, we have developed a curated database containing all the MOFs deposited in the Cambridge Structural Database (CSD). This initiative provides the MOF community with tools to extract their desired structures from the pool of crystalline structures in the CSD and to visualise their data of interest. We also developed new capabilities to enable researchers to browse and look for MOF families based on metal-clusters, chirality, surface chemistry (functional groups) and pore and network dimensionality. This has resulted in a regularly updated CSD-MOF subset of ca. 90,000 structures to date. With this tool, we have also demonstrated the power of the MOF subset for computational high-throughput screening (HTS), where we analyse their performance in different applications.
We have completed the full cycle from the screening of MOFs to the identification and synthesis of optimal materials. To move it further, we have advanced on the molecular engineering of these systems in the energy and healthcare sectors. For energy related applications, we have developed new ways of shaping MOF materials as monolithic structures based on a sol-gel process without requiring binders and/or high pressures. The monolithic materials are able to retain the characteristic structure and porosity of the powders while showing a three times higher density and therefore three times higher volumetric adsorption capacity. This has represented a significant step forward in the shaping and densification of MOFs, opening the gate towards their use in real-world industrial applications where high volumetric adsorption capacities and resilient mechanical properties are critical.
In terms of healthcare applications, we have translated our holistic approach into the use of MOFs as drug delivery vehicles. In particular, we have used MOFs for cancer therapy, transporting and protecting siRNA formulations to knockdown gene expression. Like in the case of small molecules, we first perform molecular simulations to select a MOF that favoured internalisation of the siRNA. We then confirmed the protection of MOF-internalised siRNA from enzymatic degradation. This is combined with a fundamental understanding about how cells endocyte MOF nanoparticles, using super-resolution microscopy and proteomics. Our recent work demonstrates the potential of these highly porous and biodegradable materials to improve both the efficacy and efficiency of future chemo and gene therapies.
Dr David Fairen-Jimenez is a Royal Society University Research Fellow (URF) and Reader in Molecular Engineering in the Department of Chemical Engineering & Biotechnology at the University of Cambridge, where he leads the Adsorption & Advanced Material Laboratory (AAML). His research into the application of metal-organic frameworks (MOFs) in energy applications and nanoscale drug delivery is underpinned by fundamental studies into molecular recognition and adsorption processes in nanoporous materials. His expertise has been built through integrated research which combines 1) synthesis and engineering of novel nanomaterials, 2) molecular modelling, 3) drug delivery processes for cancer treatment, and 4) sustainable industrial applications. He leads a multidisciplinary team of chemists, chemical engineers and biotechnologists.
Topics in Bioengineering