Synthesis of Biocompatible Metal-Organic Frameworks and their immobilization on surfaces

Abstract

Metal-Organic Frameworks (MOFs) are porous materials composed of metal ions or clusters linked to organic ligands by coordination bonds, leading to the formation of structures with two or more dimensions built from repeatable units. The biological application of MOFs has been studied over the past few decades, leading to the synthesis of Biological MOFs (Bio-MOFs). These biologic compatible structures are mainly employed for the delivery of active ingredients and for therapeutic and diagnostic applications. On the other hand, the integration of MOFs in devices has involved the necessity to prepare films of MOFs and their growth on functionalized surfaces, in order to obtain surface-coordinated metal-organic frameworks (SURMOFs). Therefore, in this work the preparation of the [Zn3(CCM)2] Bio-MOF based on Zn(ll) and curcumin (CCM), and its corresponding SURMOF have been studied. First, two different methodologies were developed for its synthesis: solvothermal and microwave-assisted synthesis. Consequently, the obtained products were analysed via X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy, in order to corroborate the formation and crystallinity of the Bio-MOF. On the other hand, the preparation of the corresponding [Zn3(CCM)2] SURMOF has also been studied using two different monolayers as nucleation points: curcumin SAM and eugenol derivative SAM. For the curcumin SAMs, the localized attachment of curcumin on the surfaces was carried out by the reaction of the curcumin with terminal imidazole monolayer. For the eugenol-based SAM, first a derivative of the eugenol with reactive –Si(OEt)3 groups was synthesized. Both strategies lead to the formation of patterned curcumin monolayers, obtained via micro-contact printing. Finally, the growth of the of the [Zn3(CCM)2] SURMOF on the active monolayers was performed via drop casting, layer-by-layer and solvothermal methodologies, optimizing parameters such as solvents, times and blocking of the non-patterned areas. The surfaces were characterized using fluorescence microscopy, contact angle measurements, X-ray Photoelectron Spectroscopy, Scanning Electron Microscopy and Energy-dispersive X-ray spectroscopy