Magnetic ZIF-8 as a stable support for biomolecules via adsorption in aqueous buffered solutions at pH=7

Metal-organic frameworks (MOFs) have been recently proposed as supports for biomolecules immobilization, particularly for enzymes. However, their stability under the high ionic strength aqueous solutions required for practical applications of these biocatalysts have not been evaluated. Here, it is shown that surface modifications and a careful analysis and selection of the buffer components must be accomplished to ensure the resistance of the MOF to hydrolysis, even for the previously assumed robust Zeolitic Imidazole Frameworks (ZIFs). By taking into account these considerations, and introducing polyvinylpyrrolidone (PVP) as a surfactant in the synthetic process, a resistant and stable magnetic MOF (Fe3O4@7IF-8/PVP) was obtained. Further, the loading capacity of the stabilized synthetized structures for the immobilization of a model protein, such as bovine serum albumin (BSA), was analyzed. It was found that physical interaction provides an efficient and suitable method to immobilize this biomolecule without evidence of leaching.