Prepration Of Gold Nanorods SERS Substrate And Its Application In The Characterization Of Glutathione Triggered Drug Release

Compared to spherical gold nanoparticles,gold nanorods?AuNRs?have special optical,electronic,and chemical properties characterized by unique anisotropy,great stability and biocompatibility,which has attracted much interest in the field of precious metal nanomaterials,and has a wide range of application prospects in the field of nanocomposites,functional nanodevices,nanobiotechnology and biomedicine.The self-assembly of gold nanorods into a substrate makes the properties of the gold-nanorod-substrate the coupling of optical and electrical properties of individual gold nanorods,which shows excellent synergistic properties.Surface-enhanced Raman scattering?SERS?is a phenomenon in which the electro-magnetic field on the surface or near the surface of a sample enhances in the excitation region on the surface of specially prepared metal conductor or in the sol,resulting in an increase in the Raman scattering signal of the adsorbed molecule compared to a normal Raman scattering signal,which solves the problem of low intensity of ordinary Raman spectra of some molecules.It is widely used in the fields of physics,chemistry and biomedicine.The intensity of the SERS spectrum is directly proportional to the concentration of the molecule detected.Glutathione?GSH?is the most abundant intracellular thiol in the human body and is an important natural reducing agent.The strong interaction between gold atoms and sulfydryl in GSH molecules can displace other molecules attached to the surface of the gold atom.Thus the difference between the gradients of GSH concentration inside and outside cells can be used to trigger the desorption of drug molecules conjugated on the gold surface to trigger the drug release.The details are as follows:1.High purity,uniform size gold nanorods were prepared using a seed-mediated growth method.The optical properties and morphology of the as-prepared gold nanorods were characterized by UV-vis-NIR spectrophotometer and scanning electron microscope?SEM?.The impact of pH value,amount of silver nitrate?AgNO₃?,and amount of chloroauric acid?HAuCl₄?on the morphology and purity of gold nanorods were analyzed,thereby summarizing the optimal conditions for the preparation of gold nanorods of suitable size and high purity as the basis for the assembly of gold nanorod substrates.The results showed that the pH value,the amount of AgNO₃,and the amount of HAuCl₄ all affected the aspect ratio and uniformity of the gold nanorods.2.Gold nanorods with high purity and uniform aspect ratio are self-assembled on the solid-state substrate by evaporation to form a base that stands side by side.The effect of cetyltrimethylammonium bromide?CTAB?content and concentration of gold nanorods on the self-assembly process was investigated.The morphology and properties of the substrates assembled with gold nanorods prepared under different conditions were studied.In comparison,the morphology of the gold nanorod substrate was characterized using scanning electron microscopy?SEM?,and the enhancement effect of the gold nanorod substrate was characterized using SERS.The result shows that only in the presence of CTAB,high purity of condense gold nanorods can be assembled into gold nanorods substrate with uniform morphology and stable performance.3.The gold nanorod substrate was used to study the release of 6-mercaptopurine?6-MP?covalently attached on gold surface triggered by GSH.6-MP represents the sulfhydryl drugs,and GSH represents the intracellular environment.Cysteine?Cys?was used as an control group to GSH for drug release,in which cysteine represents the reducing environment of plasma,and time and 6-MP concentrations were also studied for the adsorption of 6-MP on gold surfaces.The effect of GSH concentration on the release of 6-MP was studied.Use SERS to characterize the change in the amount of 6-MP adsorbed on the gold surface.The result shows that GSH can effectively trigger the release of 6-MP attached to the surface of gold nanorod substrates.