Cobalt-based Peroxide Mimic Enzyme And Its Biochemical Analysis Application Research

Natural enzymes have been used in various fields such as biology and medicine due to the advantages of high catalytic efficiency,substrate specificity and species diversity.However,they also have some inherent defects such as high cost,easy deactivation,and difficult transportation.Therefore,mimic enzymes have been developed continuously.Enzyme mimics can be widely used as substitutes for natural enzymes because of their high stability and low cost.Among them,nanomaterial-based enzyme mimics are widely used in catalytic processes because of their large specific surface area and high enzyme activity.It plays an important role in the fields of environmental monitoring,medical diagnosis and biological analysis.Ordered mesoporous carbon?OMC?has been considered to be an excellent catalyst support with the advantages of high specific surface area and good biocompatibility.It is often used to synthesize various nanocomposites.A cobalt-based nanozyme with peroxidase activity was synthesized by loading to mesoporous carbon.For further improving the atomic economy of cobalt,we also developed a cobalt ion-based peroxidase mimics system.Detailed descriptions are as follows:First,a cobalt oxide was grown on OMC to form nanocomposite?CoO-OMC?,which showed good peroxidase activity.Using 3,3,5,5-tetramethylbenzidine?TMB?as the chromogenic substrate,steady-state kinetics experiments were performed,the apparent maximum velocity(V_max)was 2.66×10^-7 Ms^-1 and the Michaelis-Menten constant?K_m?was3.29 mM.The method could be used for the colorimetric detection of H₂O₂.The nanocomposite could be further combined with glucose oxidase for detecting glucose in a two-step method.The glucose sensor shows a linear range of 0.1-5.0 mM with a detection limit of 68?M.This sensor was successfully used to detect blood glucose concentration in human serum.Second,Co²⁺peroxidase-like activity enhanced by a series of amino acids,peptides and proteins was investigated.For the tested 20 amino acids,we found that tryptophan?Trp?has the largest enhancement effect on Co²⁺peroxidase activity.The reaction system could effectively catalyze the oxidation of 2,2'-hydrazine-bis-3-ethylbenzothiazoline-6-sulfonic acid by H₂O₂.The dependence of the above catalytic system on HCO₃^-was confirmed and the effective catalytic combination of Co²⁺-Trp-HCO₃^-was revealed.After the experimental conditions were optimized and the reaction mechanism was explored.A simple and low-cost Co²⁺sensor was developed,which had a linear range of 10-300?M with a detection limit of 0.4?M.This sensor was successfully used for the detection of Co²⁺in actual samples such as tap water,mineral water and allochroic silicagel.