Preparation Of Cuprous Oxide Nanozyme And Study On Its Multiple Enzyme-like Activity

Natural enzymes are highly selective biocatalysts and can participate in various metabolic processes in living systems.Natural enzymes have the advantages of high catalytic efficiency and strong substrate specificity,so they are used in medicine,chemical industry,biotechnology and other fields.However,due to the inherent disadvantages of low stability,high cost,difficult separation,purification and recovery,difficult to preserve,sensitive to the environment,variability and inactivation under acidic,alkaline and high temperature conditions,the wide application of natural enzymes has been greatly limited.In order to change the limitations of natural enzymes,researchers have been working on the replacement of natural enzymes for a long time.Nanase is defined as a nanomaterial with enzyme activity,which has both the inherent excellent properties of nanomaterial and catalytic function.As a new kind of artificial enzyme,nano-enzyme has the advantages of adjustable catalytic activity,simple preparation,low cost,high stability in acid,alkali and high temperature conditions,and easy to large-scale production.Compared with natural enzymes and traditional artificial enzymes,nano-enzymes have obvious advantages.However,the existing preparation methods of cuprous oxide nanosase generally have the problems of complex operation,high cost,difficult to control the size and morphology of the product,and high equipment requirements.Cu₂O Nanozyme(CNE)is a kind of novel nanase with good biocompatibility,which has the advantages of low cost,high stability and abundant reserves.Therefore,Cu₂O Nanozyme has been widely used in anti-tumor,antibacterial,photocatalytic,biosensing and other fields.In this paper,a simple solution method is used for preparation,which is not only easy to operate,low cost,but also can control the size and morphology of Cu₂O Nanozyme,greatly improving the drawbacks of the existing preparation methods.Vitamin C(Vc,ascorbic acid)is a water-soluble vitamin that is essential in the body,and a deficiency can lead to swelling of joints and even diseases such as cancer.But excessive vitamin C easy to appear urinary system stone,diarrhea and other problems.Therefore,it is necessary to detect the content of vitamin C in food and medicine quickly and accurately.The existing detection methods are generally characterized by low sensitivity,complex operation and many interference factors.However,using Cu₂O Nanozyme to detect vitamin C not only improves these problems,but also provides a new idea for the detection of vitamin C in food,medical treatment and industrial production.In this paper,the synthesis method of Cu₂O Nanozyme with simple economic and high efficiency nanase activity and the establishment of vitamin C detection method with application prospect are studied.The specific research contents are as follows:(1)Synthesis and preparation of Cu₂O Nanozyme:Highly uniform cubic CNE was prepared by a simple solution method.Using polyethylene glycol 600 and ascorbic acid,Cu SO₄·5H₂O reduction method to prepare.The method can synthesize CNE cubes of different sizes by changing the concentration of polyethylene glycol and the addition sequence of reagents.UV-vis absorption spectrum and transmission electron microscopy were used to characterize it.It is proved that cubic CNE of 100nm,150 nm and 250 nm is successfully synthesized,and the nanomaterial has uniform size and good dispersion.(2)Study on enzymatic properties of Cu₂O Nanozyme:It was found that CNE had good activity of peroxidase,catalase and ascorbate oxidase.First of all,CNE can catalyze the color of substrate TMB in the presence of H₂O₂,and there is an absorption peak at 652 nm.In addition,when p H=4 and temperature is 75?,CNE has the highest peroxidase activity.The steady state dynamics of CNE showed that the catalytic mechanism of peroxide-like enzyme was ping-pong mechanism;Secondly,CNE can catalyze the decomposition of H₂O₂into oxygen and water,showing catalase-like activity.The optimal p H of this catalytic reaction is 10.In a certain range,the catalase activity of CNE increased with the increase of temperature,and the kinetic results showed that the catalase activity was consistent with the Michinase model;Finally,CNE catalyzes ascorbic acid to dehydroascorbic acid,producing an absorption peak at 265 nm.The optimum p H of this catalytic reaction is 6.In a certain range,the activity of ascorbate-like oxidase of CNE increased with the increase of temperature,and according to the results of kinetics,there was a dependent relationship between the initial reaction rate and substrate concentration,and its kinetic mechanism followed the Mirosinase model.(3)By analyzing the catalytic specificity of CNE on different substrates,CNE can be used for the detection of vitamin C in beverages,and common interfering substances will not affect the detection of Vc content by CNE.The results of CNE system were consistent with those of iodometry,which indicated that CNE could be applied to the determination of Vc in practical products.In conclusion,Cu₂O Nanozyme with good peroxidase-like,catalase-like and ascorbate oxidase-like activities were successfully synthesized in this paper.And CNE catalyzes the formation of oxidative dehydroascorbic acid(DHAA)under mild conditions,DHAA reacts with o-phenylenediamine(OPDA)to produce a fluorescent product that can be used for vitamin C detection.This detection method has the advantages of low cost,high efficiency,simple preparation,high selectivity and sensitivity,wide linear range,low detection limit,stable reaction and small error,etc.It can be applied to the determination of vitamin C content in actual products.