Peroxidase-like Activity Of Fe(Ⅲ)-contained Nanomaterials And Their Analytical Applications

Enzymes have high catalytic activity and substrate specificity,but the difficulty in extraction and purification,poor stability and mild reaction condition restrict the widely use of enzymes.Therefore,since the special physical and chemical properties,as well as the size,shape and the catalytical activity of nanomaterials similar to natural enzyme,the study of enzymatic activity of nanomaterials have attained more and more attention.For example,carbon nanomaterials,metal nanoparticals and metallic oxide nanoparticals.Moreover,MOFs and LDHs both possess the property of adjustable metal ion,and changeable organic ligand（or anion）.In addition,unsaturated metal ions are usually the active sites of catalytic reactions,especially the catalytic activity of Fe（Ⅲ）.Therefore,in this paper,the nanozymes that researched widely and the methods for enhanceing catalytic activity of nanozymes were summarized,the catalytic activity of MOFs and LDHs were studied.Based on that,the chemiluminescence method and colormetric method to detect H₂O₂ and glucose were developed.Firstly,the MIL-53（Fe）was discovererd with great enhancement for the chemiluminescence of luminol-H₂O₂ system in alkaline condition.The chemiluminesence intensity of MIL-53（Fe）-luminol-H₂O₂ was 20 times higher than that of luminol-H₂O₂ system.Besides,the XRD pattern of MIL-53（Fe）after the reaction of chemiluminescence has not changed,confirming that MIL-53（Fe）plays an important role in the MIL-53（Fe）-luminol-H₂O₂ system and has good stability.The possible reaction mechanism of the system was proposed based on chemiluminescence analysis,fluorescence spectroscopy analysis and capture experiment of the active oxygen free radicals.In addition,combined with glucose oxidase,a sensitive and selective method for the detection of glucose was established.There was a good linear relationship between the logarithm of chemiluminescence intensity and the logarithm of glucose concentration,with a linear range of 0.1-10 μM and a detection limit of 0.05 μM.This method results in satisfactory results in the detection of glucose concentrations in serum.Seconedly,flower-like CoFe LDH was prapared successfully by a simple method.It was found that CoFe LDH performed the high activity for luminol-H₂O₂ system as well as luminol system based on the peroxidase-like and oxidase-like acticity of CoFe LDH.A lot of experiments suggested that abundant O₂?-were generated in luminol-H₂O₂-CoFe LDH and luminol-CoFe LDH systems.The results indicated the O₂?-played an important role in the reaction with lunimol to produce CL.Based on the enhancement of CoFe LDH for luminol-H₂O₂ system,the detection methods for H₂O₂ and glucose have been established.The detection limit for H₂O₂ and glucose was 5 nM and 70 nM,respectively.We also set up a mensuration for ascorbic acid（AA）rely on the inhabition on luminol-CoFe LDH system.Lastly,due to the peroxidase-like activity,LDHs have attracted a lot of attentions in the past few years.Moreover,the morphology of nanomaterials will affect the catalytic activity greatly.Therefore,we fabricated three kinds of NiFe-LDH with different morphologies.Among them,the flower-like LDHs intercalated with sodium citrate display greatest catalytic activity.We have optimized the content of sodium citrate and chose t-NiFe-LDH-SC（0.4）as the optimal meterials.XRD pattern,IR spectra and TGA results suggested that sodium citrate intercalated in flower-like LDHs successfully.The flower-like LDHs possess highest affinity for H₂O₂ and reaction rate among three LDHs.The reaction kinetics conformed to Michelid-Menten kinetic and the mechanism agreed with ping-pang mechanism.Flower-like LDHs-based colorimetric assay have been set up to detect H₂O₂ and glucose at the end of this part.