Synthesis And Characterization Of Gold Nanowire Vesicles And The Application In Detecting Pathogenic Bacterium

The gold nanoparticle?AuNPs?,gold label silver staining method and Surface Enhanced Raman Scattering?SERS?were systematically reviewed.Due to the easy preparation,unique physicochemical property and excellent biocompatibility,AuNPs has been widely used in the field of biomedicine and analytical chemistry.In this research,a dual mode colorimetric/SERS immunosensor based on three-dimensional gold nanowire vesicles was constructed to achieve high sensitivity detection of Vibrio parahaemolyticus,which overcomes the problems of process cumbersome,time consuming,and poor stability in conventional methods.Two sets of data can mutually validate to avoid false positive and negative detection.The designed colorimetry-SERS dual-mode sensor would be very promising in various future applications.The details are as follows:1.Preparation and Characterization of Gold Nanowire VesiclesPolystyrene microspheres?PS?was used as carriers of AuNPs.Then the AuNPs were uniformly distributed three-dimensionally on the surface to form the compound of PS-AuNPs as seed solution.When the seed solution was placed in a mixture containing HAuCl₄ as gold source and ascorbic acid?L-AA?as reducing agent,the small AuNPs will grow in a seed-mediated method.By adjusting the concentration of the strong ligand paradibenzoic acid?4-MBA?,AuNPs can change to“island”,“nanowire”and“inhibited nanoparticles”structure respectively.When the PS microspheres were removed,the in-situ generated gold nanowires can form a hollow vesicle with a three-dimensional structure.This method is superior to traditional synthetic of gold nanowires due to avoiding the cumbersomeness.It will provide new ideas for the synthesis of other metal nanowires and different nanostructures.2.Evaluation of SERS performance of gold nanomaterial vesicles substrateThe gold array substrate synthesized in the first work was taken as the research object.And the probe molecule rhodamine 6G was used as a model to verify the SERS performance of the array substrate.Compared with the two substrates of“island”and“inhibited nanoparticles”,the gold nanowire vesicles?AuNW vesicles?can promote the SERS signal greatly because of the tip structure and the abundant tip-to-tip gap of the three-dimensional assembly.At the same time,more Raman molecules,which can generate effective Raman signals will be captured thanks to the hollow structure,thereby increasing the SERS intensity and lowering its limit of detection?LOD?.The average enhancement factor of AuNW vesicles substrate to R6G is as high as 9.90×10⁷,and the detection limit is as low as 10 nM.The hot pot between gold nanowires on the AuNW vesicles array based on traditional evaporation self-assembly method will be more uniform,and the coefficient of variation is less than 7.6%,improving its stability and repeatability largely.The new"AuNW vesicles substrate"shows excellent SERS performance and can realize its application in the field of biosensing and so on.3.Giant gold nanowire vesicles?AuNW vesicles?based colorimetric and SERS dual mode immunosensor for ultrasensitive detection of Vibrio Parahemolyticus?VP?Based on the AuNW vesicles structure,a colorimetric/SERS dual mode immunosensor for detection of VP was developed.The glass substrate functionalized with amino was used to construct reaction sites.The primary antibody was immobilized on the glass surface through the interaction between aldehyde groups and amino groups.Then the Vibrio parahaemolyticus?VP?was added,followed by the capture of the second antibody.The second antibody was labeled with AuNW vesicles.Then a sandwich structure of the"primary antibody-VP-second antibody"was constructed.Finally,the silver staining reagent was added and the sensor was successfully prepared.Compared with the traditional gold spheres,the larger specific surface area of AuNW vesicles can make the color change more obvious,which will reduce the LOD of the colorimetric method;Then,the AuNW vesicles structure itself can greatly enhance the magnetic field,and the silver staining process will further improve the Raman signal;Finally,the colorimetric and SERS results confirm each other to detect VP accurately.In all,the sensor is simple and fast with high sensitivity and high accuracy,which can detect low concentration of VP and has an excellent prospect in practical application.