Biomineral-inspired growth of metal-organic frameworks in gelatin hydrogel matrices

In this work we employ a biomineral-inspired growth approach to the prototypical metal-organic frameworks (MOFs) ZIF-8 and HKUST-1 using cheap abundant non-toxic gelatin hydrogels as both a matrix and macromolecular additive for crystal growth. Both MOFs are readily prepared within the hydrogel, and while ZIF-8@gelatin composites are readily dispersed in water to form colloidal solutions stable for several months, the matrix has a significantly more pronounced effect on the crystal growth and morphology of HKUST-1 directly mirroring natural matrix-mediated biomineralisation processes. Addition of small amounts of gelatin (<1 wt%) to solvothermal syntheses of the frameworks indicates that the biomacromolecule can influence particle size, and in the case of HKUST-1 leads to mesostructured aggregates of particles that can be tuned across multiple length scales.