Catalytic Oxidation Of Bile Acids And Their Applications

In Comparison with conventional metal materials,Noble metal nanomaterials,such as platinum nanoparticles（Pt NPs）,gold nanoparticles（AuNPs）and core-shell structure（Ag@Au）have more excellent photochemical,electrochemical and catalytic oxidation properties.They are widely used in many fields,such as optoelectronic devices,sensors,catalysts,information transmission and storage,fluorescent probes.In this thesis,AuNPs were synthesized by photochemical reduction method using biosurfactant bile salts as reducing agents and capping ligands,and HAuCl₄as precursor.The resulting AuNPs were used as catalyst to further oxidize bile salts,and the oxidation products were used to recognize the chiral isomer R,S-1,1’-binaphthyl-2,2’-dihydrophosphate（R,S-BNDHP）.A fluorescent probe was prepared by combination bile acid with S-binaphthol（S-BN）to detect the concentration of Fe³⁺in solution.AuNPs were synthesized by photochemical reduction of precursor HAuCl₄with biosurfactant sodium deoxycholate（NaDC）as reducing agent and capping ligand.Under UV irradiation,the hydroxyl group of NaDC was oxidized to carbonyl group,while Au³⁺ions were reduced to form AuNPs.The resulting AuNPs were further used as catalysts for the oxidation of NaDC by O₂.The size of AuNPs has an effect on the catalytic oxidation efficiency.It was found that AuNPs with smaller particle size had higher catalytic activity.The chiral recognition of R,S-BNDHP by the micelles formed by NaDC and its oxidized product 3-KHC was studied.Compared with NaDC,the micelles of 3-KHC have stronger binding ability to model molecules.Compared with R-BNDHP,3-KHC micelles showed better selectivity for S-BNDHP.AuNPs were prepared by photochemical reduction of HAuCl₄in the presence of NaC.The kinetic study shows that the photochemical reaction is a zero order reaction,and the reaction rate increases with the increase of temperature.The resulting AuNPs show excellent catalytic performance in the oxidation of NaC to its oxidation products.The enantiomer R,S-BNDHP were used as models to study the chiral recognition of NaC and its oxidation product 3,7-DKHC.It was found that BNDHP molecules were more easily embedded in the micelles formed by oxidation products of NaC.Owing to the advantages of high selectivity and sensitivity of the fluorescent probe in situ detection,a fluorescent probe based on S-BN and bile acid was developed for the determination of Fe³⁺in solution.The logarithm of the fluorescence intensity of S-BN is proportional to the concentration of Fe³⁺in the range of 0.1～550μmol/L.The detection limit of Fe³⁺can be as low as 5nm.It was found that the addition of bile acid improved the stability of S-BN-Fe³⁺detection system.This method has good selectivity and shows good sensitivity and accuracy in real sample detection.