Hollow MnFeO oxide derived from MOF@MOF with multiple enzyme-like activities for multifunction colorimetric assay of biomolecules and Hg.

In this work, a new type of hollow MnFeO oxide derived obtained from the metal-organic framework (MOF)@MOF was designed and proposed, which has intrinsic activity of mimicking enzymes of oxidase and peroxidase by adjustment pH values. Based on the colorimetric reaction and the hindrance of the oxidase-like activity in the presence of L-cysteine (Cys), as well as the recovery of oxidase-like activity due to the specific complexation of Cys and mercury (II) ions (Hg), a new type of colorimetric transmission platform for Cys and Hg detection with wide linear ranges of 1-25 μM for Cys and 0.1-15 μM for Hg has been developed. Besides, a better colorimetric sensing platform for detecting HO was established with linear ranges of 1-60 μM and 60-300 μM based on generating hydroxyl radicals (·OH). Furthermore, the hollow MnFeO oxide has high stability, excellent selectivity with good activity over a long period of time. Surprisingly, the proposed method for Cys, Hg and HO estimation can also be used in actual samples. These characteristics lay a foundation for further investigation about the catalytic activity of the hollow MnFeO oxide nanomaterials and make it show broad prospects in the field of biosensing and catalysis.