A MOF-BIOMOLECULE BIOCOMPOSITE

Metal-organic frameworks (MOFs) are reticular compounds that feature permanent porosity and large surface areas. MOFs are characterized by unprecedented chemical versatility -they can be composed of different types of metals and ligands- enabling a wide variety of structures. This characteristic allows their properties, such as chemical composition, porosity, and surface area, to be tailored, making them attractive materials for a wide range of applications. Their development has enabled their miniaturization and large-scale preparation, making them attractive for the preparation of biocomposites with biomolecules. Infiltration of the cargo in the MOF structure has been one of the main procedures for the preparation of biocomposites with drugs and biomolecules for their delivery into cells. The materials' porous structure with high surface areas enables high loadings of cargo and typically confers optimal protection. This infiltration strategy has been also applied to obtain biocomposites of proteins and enzymes located in the pore cavities of MOFs by translocation. However, this approach is limited by the size of the pore apertures, as larger macromolecules cannot penetrate and diffuse through them. The biomolecule-pore size limitation can be overcome by employing in situ encapsulation strategy. It consists in the formation of the direct encapsulation of the desired cargo by mixing it with the metallic and organic MOF precursors and obtain a porous material that physically surrounds the cargo, thus leading to the formation of the cargo@MOF biocomposite. The main problem with this in situ approach comes from the incompatibility of the synthetic conditions required by many MOFs with the integrity of fragile cargos, such as biomolecules. Therefore, there is a gap between the synthetic parameters required for MOF formation and the conditions that preserve biomolecules to overcome for the wide use of MOF-based biocomposites. So, the development of synthetic protocols to obtain MOFs that are compatible with biomolecules -specifically employing aqueous media, ambient temperature, and moderate pH- is needed.