Colorimetric Determination of Glutathione (GSH) Using Metal-Organic Framework (MOF) NiCo Layered Double Hydroxide (LDH) as a Peroxidase Nanozyme Mimic

Currently, the use of metal-organic framework (MOF)-based peroxidase (POD) mimics has been attempted for the development of colorimetric biothiol detection sensors. Furthermore, Ni/Co layered double hydroxides (NiCo-LDH), as sourced from MOF, have attracted increasing interest as enzyme mimics for colorimetric detection due to their low cost, adjustable layered structure, and composition. Herein, the hollow cubes of NiCo-LDH were synthesized with zeolitic imidazolate framework-67 (ZIF-67) as a sacrificial template. NiCo-LDH nanosheets were used to construct the hollow cubes with additional active sites exposed by the hollow structure. A series of experiments were conducted to confirm the superior catalytic activities of NiCo-LDH nanozymes as peroxidase (POD)-like inhibitors to horseradish peroxidase. The enzymatic kinetic constant Km values for NiCo-LDH nanozyme were 0.70 mM (H2O2) and 0.16 mM (TMB). Glutathione (GSH) was determined with a detection limit of 0.263 μM and a detection range from 5 to 60 μM. Meanwhile, the platform exhibited exceptional selectivity and stability. The mechanism and application of NiCo-LDH nanozymes were explored to promote the development of nanozymes with multi-metal active sites.