Colorimetric Detection Of H₂O₂ Based On Peroxidase-like Activity Of Bimetallic Co/Mn-MOFs

Hydrogen peroxide?H₂O₂?has been widely used in the fields of industry,medical,food processing and so on owing to the bleaching,oxidation and sterilization.However,excessive or illegal addition of H₂O₂ is very serious.Excessive H₂O₂ is toxic to the human body,it can cause great irritation to the skin and respiratory tract.And H₂O₂ which gets into the human body would generate hydroxyl radical?·OH?which causes the oxidative damage of macromolecular substances.Then,because of the cells necrosis or mutation,a series of diseases would occur including malignant tumors.Therefore,it has great realistic significance to detect hydrogen peroxide.The colorimetric sensing has aroused great attention in the fields of analytical chemistry and environmental monitoring,owing to its simple operation,rapid reaction,low cost and direct visual readout.In recent years,the researches on improving the performance of colorimetric sensors are mainly focused on the development of new nanomaterials,in which metal organic frame material?MOFs?emerging as an artificial mimic enzyme has been applied to the colorimetric sensing and made continuously achievements.However,most of previous works focus on employing the Fe-based MOFs as enzyme mimic,and few studies are reported about the bimetallic MOFs-based enzyme mimic,which limit their research to some extent.In view of the above problems,a two-dimensional sheet-like bimetallic Co/Mn-based MOF?Co/Mn-MOFs-1-1-150?was synthesized via an one-step hydrothermal method.Due to the peroxidase-like catalytic activity,Co/Mn-MOF-1-1-150 could catalyze the decomposition of H₂O₂ with generating·OH,which further oxidized chromogenic substrate 3,3',5,5'-tetramethylbenzidine?TMB?into oxTMB accompanied with a colorless-to-blue change of reaction solution.And the quantitative detection of H2O2 can be realized,due to the positive correlation between the concentration of the target and the color difference.The Michaelis-Menten constants?K_m?and maximum initial velocities(V_max)of the catalyst were found to be 0.27 mM and 1.64×10^-7 M s^-1 for TMB respectively,and 0.24 mM and 5.80×10^-7 M s^-11 for H₂O₂ respectively.Compared with the HRP,our material possesses better affinities with substrates.The favorable peroxidase-like activity of this material could ascribed to the synergistic catalytic effect of two metals and the two-dimensional structure with small diffusion barrier of the substrate molecules and large exposed surface area.Accordingly,we successfully utilized Co/Mn-MOF-1-1-150 to establish a platform for colorimetric detection of H₂O₂.A linear absorbance response ranging from 1 to100?M with the limit of detection of 0.85?M?3?/s?was obtained under the optimized conditions.More importantly,in order to explore the feasibility of the fabricated sensing method based on this material to detect H₂O₂ in practical samples,we determinate the H₂O₂ in human breast cancer cells?MCF-7?and spiked water samples?tap water and lake water?.The results revealed that the as-prepared bimetallic Co/Mn-MOF-1-1-150 would be a promising candidate as peroxidase for monitoring H₂O₂ levels in environment and organisms.