Research Of Fluorescence And Colorimetry Detection For Small Biomolecules Based On Graphite-phase Carbon Nitride Nanomaterials

In recent years,non-metallic graphite-phase carbon nitride has been extensively used in the realm of analysis due to its excellent biocompatibility,chemical stability,catalytic activity and optical activity.In this paper,we utilized the unique advantages of graphitic carbon nitride nanomaterials to construct the highly sensitive,fast and specific sensing platforms for the detection of small biomolecules based on the principles of static fluorescence quenching and electron transfer,which expanded the application of graphitic carbon nitride nanomaterials in optical biosensing.The main researches and conclusions of this treatise are generalized as follows:（1）Platinum-loaded graphitic carbon nitride nanosheet（Pt/g-C₃N₄）for colorimetric detection of cholesterol and H₂O₂.In this work,Pt/g-C₃N₄with superior peroxidase-like activity was fabricated by a facile reduction strategy.The systematic studies confirmed that the loading of Pt metal in graphitic carbon nitride nanosheet gained a higher affinity with substrates and accelerated the electron transfer between TMB and H₂O₂.A highly selective and facile colorimetric platform has been developed based on the cascade reaction of combined with Pt/g-C₃N₄ and cholesterol oxidase,which could quantitative detection of cholesterol in a wide range o f10～800μmol/L（R²=0.9981）with a detection limit as low as 9.35μmol/L and H₂O₂in a wide range of 5～200μmol/L（R²=0.9959）with a detection limit as low as 5.79μmol/L.In addition,we verified the capability of the constructed colorimetric sensing platform based on Pt/g-C₃N₄ in the detection of fetal bovine serum.This method also can be applied to the analysis of many other important biomolecules（glucose,organophosphorus,acetylcholinesterase and so on）that generate or consume H₂O₂.These results show the application prospect of colorimetry based on Pt/g-C₃N₄ in clinical medical detection.（2）Graphitic carbon nitride quantum dots（g-CNQDs）as fluorescent nanoprobesfor fast and enzyme-free detection of cholesterol.Rapid and sensitive detection of cholesterol has important research significance in life science and medical diagnosis.In this work,we prepared graphitic carbon nitride quantum dots with low toxicity,good photostability and good water solubility by hydrothermal method,and the fluorescence quantum yield was as high as 35%.It was found that-NH₂,-NH on the surface of graphitic carbon nitride quantum dots could form hydrogen bonds with cholesterol contain-OH,which contributing to fluorescence quenched of the graphitic carbon nitride quantum dots by more than 90%within 30 seconds.According to this phenomenon,a fluorescence detection method for cholesterol with a linear range of 0～500μmol/L was constructed,and the detection limit was 10.93μmol/L.In addition,the constructed sensor has high selectivity in the presence of various interfering reagents,and can be used for the determination of cholesterol in fetal bovine serum,which has proved its potential clinical application value.