Construction And Application Of Ceria-based Nanoenzyme

Enzymes are powerful biocatalysts,However,the low physical/chemical stability,high preparation and storage cost,associated with their low content in organisms,difficulty of separation and purification have limited their practical application.Therefore,researchers began to focus on the study of artificial enzymes and gradually shifted from the early macromolecules such as porphyrins to nanoenzymes.Among all kinds of nanoenzyme,ceria-based materials are ideal because of its unique redox properties,which has been widely used in many fields such as catalytic oxidation.In addition,it possesses good biocompatibility.Summing up the above,it is an ideal enzyme-mimic material.For the moment,on the one hand,ceria-based materials have been reported many times to mimic oxidase,superoxide dismutase,catalase and phosphatase,researches focus on its peroxidase-mimic properties is still relatively moderate.On the other hand,the improvement of catalytic performance plays a great roles.Therefore,various construction strategies,such as doping new species or controlling the nanomaterials'morphology have been developed.Based on the above two aspects,this paper mainly carried out three research work as follows:1.Controlled preparation and peroxidase-like properties of Co doped two-dimensional ultrathin CeO2 nanoplatelets.In order to investigate the peroxidase-like activity of ultrathin body-centered tetragonal(bct)phase CeO2 nanoplatelets and improve the stability of this metastable material.Here a simple solvothermal method is used to prepare the Co doped ultrathin CeO2 nanoplatelets.This material is only about 2 nm thick,and it exposes more surface ceria atoms compared with the traditional face-centered cubic(fcc)phase cerium oxide materials,therefore it has abundant reaction sites,and is considered to be promising catalytic material.However,the nanoplatelets synthesized by this method tend to ?-?stacking.For the better application in aqueous phase catalytic reaction and improve the dispersivity,3,4-DHCA ligands were used to functionalize the material to obtain Co1Cex(x=3,5,10,20,30)nanoplatelets with-COOH on the surface,after NaOH was added to ionize the carboxyl group,we got stable and well-dispersed catalyst in aqueous phase,and the original morphology and structure of the nanoplatelets could be well maintained.The as-prepared Co1Ce5 catalyst exhibited excellent peroxidase-like catalytic activity.2.A novel coordination chemistry strategy to construct ceria-based mimetic enzyme and its application in colorimetric detection.In this work,we developed a novel nanoenzyme construction strategy.CeO2 nanorods alone have no obvious peroxidase activity,and the traditional hydrothermal synthesis of nanorods have serious problems of aggregation,therefore,3,4-dihydroxyhydro cinnamic acid(3,4-DHCA)was introduced to achieve surface modification of CeO2 nanorods.One end of the 3,4-DHCA molecule has a phenolic hydroxyl group,which strongly interacts with the surface cerium atom,and the other end has-COOH,thus the carboxyl group is successfully modified on the surface of ceria nanorods.After the introduction of transition metal ions,by chelating the carboxyl group with the transition metal ions,we have successfully constructed M/CeO2 nanorods nanocomposites which have significantly enhanced peroxidase-like activities.What's more,there are still abundant uncoordinated carboxyl groups,their excellent negative charge will promote the converge of 3,3 ',5,5 '-tetramethylbenzidine(TMB)on the interface of nanoceria.Thus our ceria catalyst showed well affinity to TMB.Based on its peroxidase mimic properties,a colorimetric sensing platform of H2O2 and glucose had been successfully built.3.Application of H2O2 and glucose colorimetric detection with Mn(?)/CeO2 Mn(?)/CeO2 showed the best enzyme-like properties in the nanocomposites prepared by surface coordination chemistry.Its' easy to prepare in large quantities and well long-term stability make it have a good application potential in the colorimetric detection of H2O2 and glucose.Through experimental investigation,we have successfully built a Mn(?)/CeO2 analytical detection platform with good selectivity and sensitivity.Used to glucose detection of simulated urine samples,the results measured also agree well with the theoretical value.