Controllable Preparation Of Silver Nanoparticles And Their Surface Plasman Resonance Enhanced Fluorescence

Due to the unique physical and chemical properties,silver nanomaterials have been widely used in the fields of catalysis,antibacterial,electricity,optics and so on.The properties of silver nanoparticles depend mainly on their morphology and size,so it is of great significance to study the controllable preparation of silver nanoparticles.The surface plasmon resonance（SPR）effect of silver nanoparticles which is widely used in the surface-enhanced raman scattering（SERS）and the metal-enhanced fluorescence（MEF）.In this paper,based on the traditional method of preparing silver nanoparticles,the spherical and particle size controllable silver nanoparticles were synthesized by optimizing the experimental conditions.On this basis,the use of silver nanoparticles excellent SPR to enhance fluorescence effect to achieve the sensitive detection of Cu²⁺,PPi,thrombin.This paper mainly studies the following three aspects.1.On the basis of the traditional preparation of sodium citrate reduction of silver nitrate,the factors affecting the growth of silver nanoparticles were studied.The spherical silver nanoparticles with different sizes can be obtained by controlling the amount of seed,pH value and temperature.2.MEF effect from Ag@SiO₂ on CdS quantum dots（QDs）was studied.The fluorescence of quantum dots gets the maximum enhancement 2.3 times when the thickness of silica is 14 nm.Copper ion can quench the fluorescence of CdS,while PPi shows high affinity to copper ion on the basis of this Cu²⁺ and PPi were sensitively detected by the combination of MEF.3.An Ag@SiO₂-aptamer/cyanine（Cy5）-labeled DNA nanostructure was fabricated,where Ag nanoparticle played the role to enhance the fluorescence of Cy5 via tailoring the thickness of silica shell.Finally,the enhancement of the fluorescence intensity of Cy5 was achieved 6.3 times.In the presence of thrombin and graphene oxide（GO）,Cy5-labeled DNA dissociated from the surface of Ag@SiO₂ and was absorbed on GO surface by π-π stacking,the fluorescence from Cy5 was thus quenched.This fluorescence change was used for thrombin detection and concentration calculation.The system showed a low detection limit down to 0.05 nM and exhibited an excellent selectivity.