Study And Application Of Uric Acid Sensor For Catalytic Oxidation Of TMB/OPD By Nanomaterials

In this paper,biosensors were established based on the catalytic oxidation of TMB/OPD by nanomaterials to detect and analyze uric acid in serum and urine samples.Combining colorimetric and fluorescence methods,the sensor platforms were sensitive,efficient,easy to operate and reliable.The main contents of this paper were summarized as follows:Chapter one:The background and significance of uric acid researches,the properties and classification of nanomaterials,the introduction of biosensors and the types of uric acid detection methods was briefly discussed.It described the idea and content of this study,and prospected the application prospect of colorimetry and fluorescence in the field of uric acid detection as well.Chapter two:The chitosan stabilized gold nanoparticles（Ch-Au NPs）were used as catalytic 3,3’,5,5’-tetramethylbenzidine（TMB）-H₂O₂ system for visual and colorimetric determination of uric acid.Ch-Au NPs were successfully synthesized by chemical reduction,and showed peroxise-like activity.Theoretically,uric acid can be catalyzed by uricase to generate H₂O₂,and Ch-Au NPs can effectively catalyze the decomposition of H₂O₂ into·OH radicals.The peroxidase substrate TMB was oxidized in the presence of·OH radicals,resulting in a marked color change（from colorless to blue）.Thus,the uric acid concentration can be judged by visually observing the color change of the system.Chapter 3:Based on the ratio fluorescence and colorimetry,and using nitrogen doped carbon dots（N-CDs）,a simple dual-read sensor for the determination of uric acid was established.The biosensor relied on uricase to oxidize uric acid to produce H₂O₂,which was then converted to·OH radicals by I^-to oxidize colorless o-phenylenediamine（OPD）to produce yellow 2,3-diaminophenazine（DAP）.In the presence of uric acid,the biosensor system changed from colorless to yellow.DAP can generate 580 nm fluorescence peak at 330 nm excitation.Due to the inner filter effect（IFE）,the fluorescence intensity of N-CDs at 427 nm decreased with the presence of DAP.Therefore,as the amount of uric acid increased,the fluorescence presented by the biosensor at 427 nm will be quenched continuously,while the fluorescence at 580 nm will be enhanced.It presented a proportional response,so as to determine the uric acid.Chapter 4:Iron,cobalt and nitrogen co-doped carbon dots（Fe Co/N-CDs）were prepared by one pot hydrothermal method.Fe Co/N-CDs not only showed peroxidase-like activity,but also emitted fluorescence at 475 nm when excited at 360nm.A dual-signal biosensor based on colorimetry and ratiometric fluorescence method was constructed to detect uric acid by Fe Co/N-CDs-catalyzed oxidation of OPD.Uricase catalyzed the production of H₂O₂ from UA,and Fe Co/N-CDs catalyzed H₂O₂ into the·OH radicals,contributing to the oxidation of 2,3-diaminophenazine（DAP）from o-phenylenediamine（OPD）.DAP can quench the fluorescence of Fe Co/N-CDs by the inner filter effect（IFE）,and the fluorescence of DAP was significantly enhanced at 580 nm.Therefore,continuous addition of uric acid can affect fluorescence emission and UV-vis absorption intensity.Quantitative analysis of UA was based on the fluorescence intensity ratio of DAP/（Fe Co/N-CDs）(I₅₈₀/I₄₇₅)and color records.The outstanding characteristics of this study were as follows:（1）The synthesis process of nanomaterials was simple,and the biosensor constructed can realize the detection of uric acid in serum and urine samples;（2）Each study improved on the former.