Synthesis And Modification Of Noble Metal Nanomaterials And Their Application In Tumor Cell Imaging And Molecular Detection

Even to this day,cancer remains the first or second leading cause of human death.Researches show that early diagnosis of cancer is an effective way to reduce cancer mortality.At the same time,a large number of studies have shown that various biomarkers,including surface antigens,metabolites,mi RNA and circulating tumor cells（CTCs）,will be produced in the process of cancer transformation.Medical staff can carry out biomarkers detection on biological samples（blood,urine,tissue）to achieve early diagnosis and treatment of cancer and review of cancer recovery.Nanomaterials have many key characteristics,including size effect,payload density,surface modification and the potential to enhance the effect of small molecules,which make them promising candidates for cancer treatment.In particular,noble metal nanomaterials have significant advantages in physical and chemical properties,mainly reflected in surface and interface effects,volume effects,quantum size effects and macroscopic quantum tunneling effects.These advantages enable them to be used in electrochemical,fluorescence and surface-enhanced Raman spectroscopy detection of cancer biomarkers.However,the present methods for preparing noble metal nanomaterials still have some challenging,such as harsh synthesis conditions（high temperature）,complex preparation procedures,difficult purification and so on.So it is urgent to explore new methods for synthesizing noble metal nanomaterials.Therefore,the aim of this study is to investigate simple,effective and green methods for synthesizing noble metal nanomaterials,further apply the synthesized nanomaterials to biomedical applications,such as tumor cells detection and imaging.Based on these reasons,the main contents of this paper are as follows:（1）A novel turn-on fluorescent sensor for the sensitive detection of glutathione via goldnanoclusters preparation based on controllable ligand-induced etchingA facile one-pot chemical etching approach is reported to simply and rapidly prepare gold nanoclusters capped with luminol（Lum-Au NCs）in an alkaline aqueous solution at room temperature.A series of characterization studies have been carried out to explore the morphology,the optical properties and chemical components of Lum-Au NCs.The average diameter of Lum-Au NCs is 1.8±0.3 nm,exhibiting fluorescence near 510 nm upon excitation at 420 nm with a quantum yield of 14.29%and an average fluorescence lifetime of 9.47 ns.On the basis of the ligand-induced etching of glutathione（GSH）to the intermediate（luminol capped gold nanoparticles,abbreviated as Lum-Au NPs）,a novel and simple method for the fluorescence determination of GSH has been established.The method displays a good linear response in the range of 0.05–300μmol L^-1 toward GSH with a limit of detection of 35 nmol L^-1.This detection strategy with high sensitivity and selectivity facilitates its practical application for the detection of GSH levels in cell extracts.The in vitro cells results illustrate that Lum-Au NCs have good biocompatibility and can be used to readily differentiate normal cells and tumor cells by fluorescence imaging.（2）Preparation of fluorescent probe Ce6@Lum-Au NPs and its application in tumor cell imagingChlorin E6（Ce6）and luminol loaded fluorescent gold nanoparticles（Ce6@Lum-Au NPs）are designed and constructed as fluorescent probes for tumor cell recognition and imaging analysis.Firstly,luminol-gold NPs（Lum-Au NPs）have been initially built,and then successfully loaded the fluorescent receptor Ce6 to prepare the fluorescent nanoprobes（Ce6@Lum-Au NPs）with green synthesis,i.e.,with biocompatible agents and mild temperature.The as-prepared fluorescent Ce6@Lum-Au NPs can efficiently and sensitively realize fluorescence bioimaging of cancer cells.The relevant bio-sensing mechanism is pertaining to the presence of hypochlorite（Cl O^-）,hydrogen peroxide（H₂O₂）in cancer cells could readily interact with luminol to produce chemiluminescence,which can activate the Ce6 component to emit near-infrared（NIR）fluorescence.Based on the high concentration of H₂O₂ in the micro-environment of tumor cells,the strong fluorescence signal emitted by Ce6@Lum-Au NPs in tumor cells can be detected,thus achieving efficient and sensitive fluorescence imaging of tumor cells.It is revealed that Ce6@Lum-Au NPs promise to be effective fluorescent nanoprobes for early diagnosis of cancer and bioanalysis of other diseases.（3）Highly sensitive detection of oxidation stress in single tumor cell based on micro-nano electrodes and micro-nano manipulation systemBased on the electrochemical etching technique and the electro-deposition technique,a new carbon fiber microelectrode（CFME）for detection of H₂O₂ is constructed with a rapid and low-cost method.The potential applications of these microelectrodes in electrochemical bioanalysis have been explored.When the CFME treated by electro-deposition,Pt nanoparticles modified carbon fiber microelectrode（Pt/CFME）are obtained and demonstrate an excellent electrochemically catalytic activity,exhibiting a wide linear in relevant detection of H₂O₂,ranging from 0.044–12.30 mmol L^-1 with the limit of 17.3μmol L^-1.In addition,a combined platform of electrochemical scanning microscope（SECM）,micro-nano manipulation system and microscope imaging system is built to detect the oxidation stress state of single tumor cell in real time with high sensitivity.Based on the Pt/CFME and combined platform,the H₂O₂released from human glioblastoma cells（U87）when stimulated with ascorbic acid（AA）is detected in real time.