Preparation And Application Of Novel SERS Nanoprobe

Recently, Gold nanomaterials have been widely studied in many fields, such as biological, medical application and immunoassay. Because their properties are closely associated with their shapes, people have tried many ways to prepare gold nanomaterials with different shapes, gold nanosperes and gold nanorods are the most popular. Thus, we synthsized gold nanosperes and nanorods and then investigated their application in SERS.(1) Improve the yield of low aspect ratio nanorods. We decrease the addition of seed and get a very high yield of low aspect ratio nanorods, but in the same time, the nanorods are inclined to form nanopillar.(2) Prepare sterically stabilized, surface-enhanced Raman scatterring-tagged gold nanorod probes, and then used for immunoassay. We report the immunoassay application of sterically stabilized, surface-enhanced Raman scatterring (SERS)-tagged Au nanorod (NR). The probes were prepared by coadsorbing Raman-active molecule 4-mercaptobenzoic acid and biocompatibleα–mercapto–ω–carboxyl polyethylene glycol (HS-PEG-COOH) on the surfaces of Au NRs. In this sort of nanoparticle probes, the long PEG chain provide steric stabilization to the probes so that they could survive in adverse conditions; whereas, its terminal carboxyl group could bind target entity, which imparts detection/recognization functionality to the probes. When the probes recognize antigen (through the classicial"sandwich"structure that was formed due to the high binding specificity between antibody on the probe, detected antigen, and capture antibody on a solid substrate), the recognition can be signaled by the SERS signals of 4-mercaptobenzoic acid. Furthermore, one can optimize the SERS signal, i.e., detection sensitivity, by tunning the aspect ratio of the Au NRs. Therefore, the detected concentration for a single component antigen was as low as 1×10^–9 mg·mL^–1.(3) Prepare a new type of gold nano SERS tags. We adsorpt a Raman Scatterring-Tagged PEG(DNBA-PEG) on the surfaces of nanoparticles and nanorods, then coat them with silica by St?ber method, and finally get a new type of gold nano SERS tags. This method is particularly useful for the preparing of gold nano SERS tags, for that, it can not only replace the CTAB around the gold nanorods, then providing sufficient stability for the coat of silica,but also show enough SERS signal as a tags.