Mn Oxide Nanowire/ZIF-8 Composites with Multiple Enzyme-like Activities for Enantioselective Glutamate Sensing

A composite material of Mn oxide nanowires and ZIF-8 (Mn_xO_y NWs@ZIF-8-RD) with controllable sizes and morphologies (rhombic dodecahedron-shape) was successfully synthesized under mild reaction conditions. The systematic investigation into the effects of synthesis conditions of the material on their microstructure and crystalline morphology was conducted. The material function as "tandem enzymes", exhibiting multiple enzyme-like activities, such as peroxidase (POD)- and glutamate-oxidase (Glu OXD)-like activities. Kinetic studies reveal that the Mn_xO_y NWs@ZIF-8-RD has excellent enzyme-like catalytic activity, with high substrate affinity and a maximum reaction rate of (H₂O₂: 840.52 × 10^-8 M·S^-1). Mn_xO_y NWs@ZIF-8-RD shows remarkable enantioselectivity for Glu enantiomers based on its POD- and Glu OXD-like activities. By integrating theoretical and experimental approaches, the recognition mechanism was preliminarily elucidated. In short, this study offered valuable insights for developing sophisticated functional materials and provided methodological references for Glu enantiomer recognition and quantitative detection.