Assembly And Application Of Gold And Silver Plasma Satellite Structure

The local surface plasmon resonance(LSPR)phenomenon of noble metal nanoparticles made them tohave excellent optical and physical properties that allow them to be used as sensitive sensors,functional nanoprobes,and as effective catalysts.In particular,by regulatingsynthesis methods,surface functionalization techniques and different nanoparticle self-assembly techniques,a label-free plasma sensor with reasonable design,excellent performance and targeted specificity is prepared.It's real-time,fast,high sensitivity,low detection limits for biometric detection at a single nanoparticle level.Therefore,a biosensor based on gold nanospheres and silver nanosphere assemblies was prepared to detect telomerase activity.The main contents are as follows:1.Construct a satellite structure biosensor based on gold nanospheres and silver nanospheres.In the first step,seed crystals were prepared by sodium citrate reduction method,and then large-size gold nanospheres were synthesized as a satellite structure core by hydroxylamine hydrochloride growth method,and fixed on the surface of ITO glass,then modified the probe DNA molecule on the surface of gold nanospheres by Au-S bond.In the second step,the silver nanosphere is prepared by the sodium citrate-tannic acid double system reduction method,and then in order to modified the DNA that complementary to the base of the probe DNAmodified in gold nanosphere surface,the surface of the silver nanoparticle is adjusted by adjusting the pH.Finally,the surface-modified silver nanosphere and the gold nanosphere are assembled by DNA complementary,and form a hairpin structure.Characterization and analysis by dark field microscopy and single-particle localized surface plasmon resonance spectroscopy showed that the gold nanospheres and silver nanospheres were assembled well.2.Detection of telomerase activity by assembly of gold nanospheres and silver nanospheres.Detection and analysis of telomerase activity was carried out by localized surface plasmon resonance scattering spectroscopy of single particles.The active telomerase can lengthen the telomere primer chain by way of adding(TTAGGG)repeat in the presence of deoxyribonucleoside triphosphate,and the extended repeat fragment cancomplementarythe hairpin DNAand replace silver nanospheres.The substitution caused a change in the color of the single particle,and the corresponding single-particle localized surface plasmon resonance scattering.The amount of red shift caused is linear with the activity of telomerase.At this point,the detection of telomerase activity can be achieved at the single particle level,while the visual detection of telomerase activity can be achieved by change in the color of the single particle.3.Surface Raman-enhanced bioprobe was prepared by solution state assembly of gold nanospheres and silver nanospheres.Firstly,50 nm gold nanospheres and 20 nm silver nanosphere solutions were prepared separately.Then the probe DNA and Raman molecule 4-MBA were modified on the surface of the gold nanospheres,and the DNA strands complementary to the bases of the probe molecules were modified on the surface of the silver nanoparticles.The assembly concentration ratio of the two nanoparticles is based on the base complementary pairing to obtain a better solution state satellite structure Raman bioprobe.The TEM and Raman spectra were used to characterize the Raman bioprobes of the satellite assembly structure of gold and silver nanospheres.