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Catalytic Activity Of Nanomaterials As Oxidase Mimics And Its Application In Food Analysis

Posted on:2016-12-21Degree:MasterType:Thesis
Country:ChinaCandidate:W J QinFull Text:PDF
GTID:2271330461467047Subject:Analytical Chemistry
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Natural enzymes are applied in many fields due to their high catalytic efficiency and strong substrate specificity. However, they have disadvantage of inactivation, high preparing cost, demanding storage conditions. These factors limit their applications. Thus, the development of natural enzymes mimetic that possessing superior stability and catalytic activity is becoming one of the significant research fields which draws more public attention. Since Fe3O4 magnetic nanoparticles (MNPs) were reported to possess intrinsic peroxidase-like activity, many nanomaterials such as some metal oxide nanomaterials, noble metal nanomaterials, and carbon nanometerials displayed intrinsic peroxidase-like activity. Their application in the analysis testing also made great development. However, there were fewer reports about nanomaterials possessing intrinsic oxidase-like activity class oxidase activity. And they were also less application in the detection.With the rapid development of China’s national economy, the improvement of people’s living standard continuously, people is higher and higher requirement for the nutrition and quality of food. Therefore food analysis, as for food composition analysis and evaluation of food quality, guarantee the quality of the food, is particularly important. Based on the above reasons, this dissertation is focused on the development of novel oxidase-like nanomaterials- Co3O4 NPs and GO@ Co3O4 NPs, the study of catalytic mechanism and the application in food analysis. The dissertation consists of four chapters:Chapter 1:The development of nanomaterials as mimic enzyme and its application in detection in recent years was summarized.Chapter 2:Co3O4 nanoparticles were preparated and their intrinsic oxidase-like activity was investigated. The results showed that Co3O4 nanoparticles can catalytically oxidize peroxidase substrates, such as 3,3’,5,5’-tetramethylbenzidine (TMB) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), to form colored products, in the absence of exogenously added H2O2. Furthermore, the mechanism was studied by XPS、EPR, etc. The results showed that the oxidase-like activity of the Co3O4 NPs may probably be originated from their ability of electron transfer between peroxidase substrate and oxygen absorbed on the surface of the Co3O4 NPs.Chapter 3:On the basis of chapter 2, a colormetric approach to detect sulfite and a fluorescence approach to detect thiamine were established based on the oxidase-like activity of Co3O4 NPs. Under the optimum conditions, the linear range of detection of sulfite and thiamine were 0.2×10-6 to 1.6×10-5 M and 3.5 ×10-5 to 8.5 ×10-4 M, respectively. Detection limit of sulfite and thiamine were 5.3×10-8 M,1.7x10-5M. The methods were used to detect sulfite in foods and thiamine in flour.Chapter 4:we preparated GO@ Co3O4 NPs and discovered they possess intrinsic oxidase-like activity. The mechanism was studied. At last, GO@ Co3O4 NPs were used as colorimetric sensor for the detection of Vitamin C in food. Under the optimum conditions, the linear range of detection of Vitamin C was 5X 10-5 to 1.7 X 10-4 M and a detection limit of 7.0 × 10-7 M. This method is simple, inexpensive and high sensitive for food Vitamin C detection.
Keywords/Search Tags:nanomaterials, cobalt oxide, oxidase mimics, food analysis
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