Enhancing the Stability of Cu-BTC Metal-Organic Framework via the Formation of Cu-BTC@Cu₃(PO₄)₂ MOF Core-Shell Nanoflower Hierarchical Hybrid Composites

Hybrid organic-inorganic nanoflowers (NFs) have recently emerged as a critical tool in enhancing the stability and activity of biomolecules due to their expansive surface area and porosity. The delicate petal-like features of NFs offer innumerable sites for biomolecule adsorption, including but not limited to proteins, amino acids, and enzymes. Cu-BTC, a copper-based Metal-Organic Framework (MOF) has been hindered in its potential for diverse applications by its instability in humid and aqueous conditions. To overcome this limitation, this study explores the stabilization of Cu-BTC via the mineralization of its surface with the formation of copper phosphate nanoflowers (NFs). To initiate the mineralization process and provide a template for the growth of the NFs, a physiologically rich amino acid medium is employed. The inclusion of amino acids in the RPMI medium played a crucial role in the preservation of the Cu-BTC hierarchical structure by facilitating the self-assembly of copper phosphate nanoflowers on its surface, thereby producing a Cu-BTC@Cu₃(PO₄)₂ core-shell structure. The innovative mechanism behind the formation of copper phosphate nanoflowers in this study and its consequential stabilization of the Cu-BTC MOF structure underscore its novel nature.