Gold Nanoflowers: Preparation, Assembly, And Their Sers Studies

Surface-enhanced Raman scattering(SERS)has potential in biological,medical,physical,chemical and environmental monitoring applications.As a spectual analytical method,the preparation of an active substrate with the characteristics of strong enhancement and uniformity is principal.Quantitative or semi-quantitative detection can be realized through the design and synthesis of SERS-active nanostructures.Sharp edges and corners make the nanoparticles more sensitive to the changes in the local dielectric environment and thus greatly enhance the intensity of the surrounding electric field.Therefore,coronal nanostructures such as gold nanostar and gold nanoflower can be better applied to ultra-sensitive sensing such as LSPR sensing,surface enhancement Raman scattering(SERS)etc..Researches show that gold-sulfur bond(Au-S)can generate strong interaction and that the displacement of Au-S bond can be mediated by sulfhydryl groups.The behavior of Au-S bond displacement is wildly involved in the research of molecular biology,analytical chemistry,surface science and materials science.Based on the SERS-active substrate constructed by gold nanoflower,the SERS study of the Au-S bond displacement on the surface of gold nanoflower was carried out.The details are as follows:1.Using seeds-mediated method,gold chloride acid(HAuCl4)was reduced by ascorbic acid(AA)with cetyl ammonium chloride(CTAB),and cetylpyridinium chloride(CPC)which acted as surfactants.By adjusting the ratio of hydroquinone,chloroauric acid and gold seed in the system,the roughness and particle size of gold nanoflower surface were regulated.The fabricated gold nanoflowers(GNFs)holds the advantages of high yield,excellent monodispersity and good stability.Optical properties from visible light to near infrared can be controlled.The results show that the surface of gold nanoflower has rich"hot spots" which owns excellent SERS enhancement performance that meets the needs of SERS testing.2.The behavior of glutathione(GSH)-mediated Au-S bond diaplacement was studied systematically.5N-nitrobenzoic acid(DTNB)was used as Raman signal molecule to detect the relation between the intensity of SERS signal and the concentration of GSH,indicating the influence of GSH on the displacement of Au-S bond,and thus constructed the SERS detection method based on Au-S bond displacement through glutathione.3.Use 6-mercaptopurine(6-MP)as a Raman signal molecule to help construct a gold nanoprobe with SERS function.6-MP was connected to GNFs surface through Au-S bond.Study of the displacement of high concentration of GSH to 6-MP on GNFs was conducted.The effect of glutathione-s-transferase(GST)on GSH-substituted 6-MP at low concentration of GSH was further studied.Based on the discovery that GST can accelerate the 6-MP displacement,a highly sensitive SERS detection method was established.4.The method of using liquid phase nanoparticles was improved by using a uniform and stable solid substrate through the electrostatic self-assembly of GNFs on the surface of the conductive glass.The effects of serum and tissue homogenate on the signal of solid-phase SERS active substrate were investigated.The effects of different concentrations of carbon tetrachloride-induced liver injury in mice were evaluated.5.The micro-SERS solid-phase substrate was constructed and the glass capillary was drawn into a needle-like structure.The GNFs were assembled on the surface of the glass needle by electrostatic self-assembly method and the modified needle shows excellent effect of SERS enhancement and the highly sensitive detection of intracellular was achieved.