Application Research Of Gold Nanoclusters In The Detection Of Biomolecule Hydrogen Peroxide And Cytochrome C

Fluorescent gold nanoclusters are a new type of nanomaterial composed of several to several tens of gold atoms.Gold nanoclusters has many excellent properties,such as good biocompatibility,low toxicity,better stability,highly quantum yield.Fluorescent gold nanoclusters have been used to develop nano-analysis methods and have been successfully applied to the detection of small molecule,ion,protein detection and biological imaging.Gold nanoclusters also have the activity of peroxidase;this property has been used to develop a number of colorimetric and photometric methods.In this thesis,a ratiometric fluorescent nanosensor was constructed by integrating peroxidase-like catalytic and fluorescent bifunctional properties of glutathione protected gold nanoclusters(GSH-AuNCs).The ratiometric fluorescent nanosensor can be applied for the determination of H2O2 and glucose.The detailed contents are as follows.Part one.Bifunctional gold nanoclusters enable ratiometric fluorescence nanosensing of hydrogen peroxide and glucose.The accurate quantifcation of hydrogen peroxide(H2O2)and glucose is essential signifcance in clinical diagnosis.Herein a selective and sensitive ratiometric fluorescent nanosensor was developed for the determination of H2O2 and glucose by integrating peroxidase-like catalytic and fluorescent bifunctional properties of glutathione protected gold nanoclusters(GSH-AuNCs).The GSH-AuNCs exhibit inherent peroxidase-like activity and accelerate the decomposition of H2O2 into hydroxyl radicals.The produced hydroxyl radicals oxidize terephthalic acid(TA),a typical non-fluorescent substrate of peroxidase,to a highly fluorescent product hydroxyterephthalate(TAOH).Upon excitation with single-wavelength at 315 nm,dual-emission fluorescence peaks were recorded at 430 and 600 nm simultaneously.The fluorescence signal of TAOH at 430 nm continuously increased with increasing the concentration of H2O2 while the fluorescence signal of GSH-AuNCs at 600 nm remained unchangeable.Based upon on these facts,a ratiometric fluorescent nanosensor was fabricated for H2O2 assay with TAOH as response unit and GSH-AuNCs as reference,respectively.By converting glucose into H2O2 with catalytic oxidation of glucose oxidase(GOx),this nanosensor was further exploited for glucose assay.Under the optimum conditions,the detection limits of 10 nmol/L H2O2 and 20 nmol/L glucose were acquired.The relative standard deviations were less than 5%for both H2O2 and glucose(5.0 ?mol/L solution,n=11).The practicability of the nanosensor was verifed by the determination of glucose in human serum samples.Part two.Inhibitory fluorescence determination of Cytochrome c based on its catalytic effect on gold nanoclusters with hydrogen peroxide.Cytochrome c is a multifunctional enzyme and has the effects of regulating energy metabolism and regulating cell apoptosis.Cytochrome c participates in a plurality of physiological processes of the cell.It is of great significance to establish a fast,sensitive and simple method for the detection of cytochrome c.It was found that Cytochrome c has a weak inhibitory effect on the fluorescence of GSH-AuNCs.In the presence of H2O2,cytochrome c can catalyze the reaction of GSH-AuNCs with H2O2,causing a strong quenching effect on orange fluorescence of GSH-AuNCs.The fluorescence intensity of the GSH-AuNCs was gradually decreased with the increase of the concentration of cytochrome c.Based on these observations,a simple and rapid fluorescence method was established for detecting cytochrome c.The linear range for cytochrome c was 0.1?10.0?mol/L and the detection limit was 0.034?mol/L.The method has good selectivity to cytochrome c and has been used for determination of cytochrome c in serum.In a summary,we synthesized the GSH-AuNCs via "one-pot" method.By combining peroxidase-like catalytic and fluorescent properties of GSH-AuNCs,we developed a ratiometric fluorescent nanosensor for the determination of H2O2 and glucose.Beside,by using catalytical effect of cytochrome c on the gold nanoclusters with H2O2,we developed a nhibitory fluorescence method for determination of Cytochrome c.The methods have the advantages of convenient operation,low cost,high sensitivity and good selectivity.It has been successfully applied to the determination of glucose and cytochrome c in serum.This study is of great significance for the diagnosis of related diseases and the development of drugs.