Preparation Of CuS Based Peroxidase-mimicking Materials For Colorimetric Detection Of Biomolecules

Nanozymes are a class of nanomaterials with enzyme-mimicking properties.Compared with natural enzymes,nano-enzymes have the unique advantages of controllable synthesis,low cost,high stability and easy large-scale preparation,and are widely used in biomedicine and the detection and prevention of the environment.Cu S nanoparticles,as a narrow bandgap p-type semiconductor nanomaterial,have potential application prospects in the fields of nanozyme catalysis and photothermal therapy due to their tunable band structure,high carrier mobility and near-infrared absorption characteristics generated by the d-d transition of Cu²⁺.However,the lower catalytic activity and weaker affinity to substrates limit the production and application of Cu S nanomaterials.In the process of solving the above problems,researchers found that metal cations doping can increase the number of hole-electron pairs in Cu S nanomaterials,enhance the transport rate of carriers,and thus enhance their peroxidase-mimicking activities.In addition,the introduction of metal-organic framework materials as enzyme immobilization carriers can enhance catalytic activity of the enzyme and broaden its application range.The carrier material ZIF-8,as a new porous MOFs material widely used in the field of enzyme immobilization,cprovides more active sites and stronger adsorption capacity and effectively improves the affinity of enzymes to substrates.In this thesis,undoped Cu S nanoparticles and Cu S nanoparticles doped with different proportions of Ni²⁺which are coated with sodium citrate were first synthesized,and the optimal doping concentration of Ni²⁺was explored.Compared with undoped Cu S nanoparticles,Cu_0.8Ni_0.2S nanoparticles show the enhanced peroxidase-mimicking activity,and the photothermal performance is also improved to a certain extent.Then the effect of photothermal effect on the enhancement of peroxidase-mimicking activity is studied.In the further research,ZIF-8 was selected as the embedding material of Cu_1-xNi_xS nanoparticles,and Cu_0.8Ni_0.2S nanocomposites prepared with ZIF-8 as the embedding material exhibited more excellent catalytic performance.The specific research contents are as follows:（1）Cu_1-xNi_xS nanoparticles were synthesized from copper nitrate,nickel nitrate and sodium citrate.The carrier transport rate inside the copper sulfide nanoparticles was accelerated by the doping of Ni²⁺,and the catalytic efficiency of peroxidase was enhanced.Based on this,the sensitive colorimetric detection of GSH was carried out,and the lowest detection limit reached 0.53μM,which was better than that of undoped Cu S nanoparticles.In addition,the photothermal properties of Cu_1-xNi_xS nanomaterials were studied,the photothermal performance of the materials were measured,and the effect of photoheat on the peroxidase-mimicking activity and catalytic efficiency of the prepared nanomaterials was explored.By irradiation with 808 nm laser,the activation energy required for catalytic reactions was reduced,the concentration of free electrons in the materials was increased,and the catalytic efficiency of the material was enhanced.（2）ZIF-8 was prepared with zinc nitrate and 2-methylimidazole as raw materials.Then,in the process of ZIF-8 synthesis,Cu_1-xNi_xS nanoparticles were incorporated into the precursor solution of ZIF-8 as peroxidase-mimicking enzymes.Cu_1-xNi_xS nanoparticles were in situ encapsulated in ZIF-8 to form Cu_1-xNi_xS@ZIF-8 immobilized enzyme system.Subsequently,the peroxidase-mimicking activity of the material was investigated.The carrier material ZIF-8 provided more active sites,improved the affinity and adsorption ability of the enzyme to the substrate,and enhanced the catalytic efficiency of the material.Then the colorimetric detection of glutathione was carried out,and the lowest detection limit reached0.37μM,showing higher sensitivity and selectivity.