New Methods Of Biological Analysis Based On The Local Surface Plasma Resonance Effect Enhance

The unique optical property of gold nanoparticles has always been a research hotspot.The studies and application of gold nanoparticles have attracted widespread attention with the developments of nanoscience and nanotechnology in the new century.The localized surface plasmon resonance?LSPR?effect of gold nanoparticles is closely related to its own properties and external environment.Therefore,we can control the LSPR properties of gold nanoparticles by changing their size or shape.At the same time,the reactions and changes on the surface of nanoparticles can affect the refractive index of the medium and the dielectric constant of the medium,and thus affect the LSPR performance of gold nanoparticles.The spectral properties of LSPR,in turn,gotten through the spectral changes,we can also indirectly observe and monitor the changes of the particle surface or medium environment.When the distance between the gold nanoparticles is less than 2.5 times of their diameter,the plasmon resonance coupling effect occurs between the nanoparticles,and this coupling can significantly change and enhance the LSPR properties of the nanoparticles.Scientists have sought to construct special structures of gold nanoparticles to achieve a stable plasma resonance coupling effect over the decade of years.Among them,the gold core-satellite nanostructure is very interesting.In this paper,two different core-satellite nanostructures are constructed to achieve different applications based on the enhancement LSPR effect,details are as follows:?1?Electrochemically-driven gold core-satellite nanostructure based on LSPR effect:The cross-discipline of supramolecular chemistry has been widely applied in recent years.As an important branch of supramolecular chemistry,host-guest chemistry has attracted much attention.The host-guest inclusion effects of cyclodextrin and ferrocene have been successfully applied to gels and vesicles but were rarely applied onto nanoparticles.We modified the SH-capped?-cyclodextrin and SH-capped-alkyl-ferrocenes to gold nanoparticles,and achieved core-satellite nanostructure assembly based on the strong host-guest interaction.At the same time,because the ferrocene molecule's valence state has a great influence on the inclusion constant,the oxidation state of the ferrocene leaves the cyclodextrin;the reduced ferrocene tightly connects with the cyclodextrin.Therefore,the ferrocene valence could be changed through the addition of voltage stimulation.And we could understand the changes of LSPR properties of particles,and indirectly detect the detachment and reorganization of the core-satellite nanostructure through the observation of gold nanoparticle scattering spectrum.?2?Construction of gold core-satellite nanostructure based on LSPR for detection of glutathione:Glutathione is an important thiol-tripeptide in the human body.It plays an important role in detoxification,anti-oxidation,and free radical scavenging in the body.Glutathione is commonly used to detect heavy metal ions such as lead,arsenic,and mercury,since it has a strong affinity for heavy metal ions.In addition,DNA-modified gold nanoparticles have continued to heat up since Mirkin used for detection.Its high stability and high biocompatibility promote its wide application.In this chapter,T-Hg²⁺-T couples were constructed through the properties of mercury ions capable of binding two T bases to form a gold core-satellite nanostructure.According to the stronger binding ability of mercury ions and glutathione,the structure is destroyed and the properties of the LSPR are changed.A novel detection method was achieved by establishing connection with the amount of spectral blue shift and the concentration of glutathione.