The Application Of Gold And Silver Core-Shell Nanocubes In Biological Sensors

Hydrogen sulfide（H₂S）,compared with nitrogen oxide（NO）and carbon monoxide（CO）,as a new type of important gas signaling molecule has attraced more attention in molecular biology research in recent decades.H₂S equilibrates with HS^-and S^2-in biological,and it was related to physiological processes and diseases.How to detect low concentration of hydrogen sulfide on high sensitive and real time leve has become the focus.Noble metal nanoparticles have been widely used in catalysis,imaging,chemical detection,biosensing,and drug delivery owing to its unique LSPR optical properties.It’s different with the traditional sensors,that the noble metal LSPR sensor has features of label-free,rapid,real-time analysis.Therefore,in this paper,gold and silver core-shell nanocube（Au@Ag NC）as biosenor had realized real-time detection of H₂S on a single particle level.Au@Ag NCs were synthesized using 30 nm Au sphere as seeds which is synthesized using two-steep procedure.In the presence of S^2-or HS^-,a layer of Ag₂S film can be rapidly formed on its surface.Because of the dielectric constant of Ag₂S is quite different from that of Ag,the process of this change could be observed directly from the single parricle scattering spectrum and the color picture.The scattering peak red shifts of particle show a good linear relation with the concentration of sulfide ion,and it can be used as a novel nanoscale bioprobe for the detection of trace hydrogen sulfide.In this paper,the spectral changes of single particles were further verified by UV-vis adsorption spectra in the solution system.The results show that the concentration of hydrosulfide ion in the range of 0.1 nM-1μM is in good linear relationship with the red shift of the scattering peak of the nanometer scale plasma plasmon sensor,and the detection limit can reach 0.04 nM.In addition,we further try to study the relationship between nano-structure of the photosensitive DNA in the Au@Ag core-shell NCs which its configuration would be change by laser control and the single particle LSPR scattering spectrum.It based on the DNA folding technology to fabricate the triangular pyramid structure,one of which was single stranded and embedded in the photosensitive unit,and using the different wavelengths of excitation light to realize the regulation of DNA complementary pairing process.So,the effect of the change of DNA nanostructures on single particle scattering spectra was studied deeply,which provides the basis for the further development of nano-scale photosensitive multi-order memory based on Au@Ag NCs.