CTAB-Assisted Formation of Hierarchical Porosity in Cu-BDC-NH₂ Metal–Organic Frameworks and Its Enhanced Peroxidase-like Catalysis for Xanthine Sensing

A novel porous metal-organic framework (MOF), pCu-BDC-NH₂, with hierarchical porosity was synthesized using cetyltrimethylammonium bromide (CTAB) as a pore-generation agent. In addition to its common functions including structure-directing ligands or soft micelle templates, the judicious use of CTAB effectively modulated pore architecture in Cu-BDC-NH₂ MOFs. With additional mesopores generated during the synthesis process, the intrinsic MOF scaffolds further obtained pore hierarchies and interconnectivity, enabling efficient substrate access to the active metal centers, and thus significantly facilitated catalytic performance. As a proof of concept, we applied the finely engineered porous MOF pCu-BDC-NH₂ in a cascaded enzymatic system for xanthine sensing. This colorimetric biosensor exhibited a low detection limit of 0.11 μM, and a wide linear range of 1–120 μM. Furthermore, the sensor demonstrated exceptional stability, reproducibility, and was independent of interferences. Our simple yet effective method may find broader applications in tailoring pore architecture, enabling finer engineered structures to improve catalytic activities of nanomaterials.