Polysaccharide templated biomimetic growth of hierarchically porous metal-organic frameworks

Metal-organic frameworks (MOFs) are versatile nanostructured materials that find applications in different fields, spanning from separation, adsorption, sensing and catalysis to health care and nanomedicine. Their association with (bio)polymers has been recognized as a milestone for their processing into scalable devices, well-suitable for applied technologies. Herein, we investigated the templating growth of HKUST-1 and ZIF-8 in a colloidal solution of different molecular weight chitosan biopolymers under various reaction conditions. Besides isolating nanostructured polysaccharide-MOF hybrids with hierarchical porosity, we also succeeded in shaping the material body as flexible films, porous monoliths and self-standing microspheres. This templating route was successfully expanded to binary chitosan-alginate and chitosan-starch colloidal solutions, which result in flexible films with enhanced molecular diversity. The preliminary assessment of Red Congo dye removal from contaminated water revealed that open-porous chitosan-MOF nanohybrids outperform microporous MOF and marginally porous chitosan. These findings open novel opportunities for the use of such functional carbohydrates as bio-based adsorbents and chemical scavengers.