Preparation Of Multi-branched Gold Nanoparticles And Spectroscopic Analysis Of Metal Ions

The optical and photoelectric property of gold nanoparticles closely related with its shape.Different shape of nanoparticles has unique exciton resonance response.And strong anisotropic particles presents multiple surface plasmon resonance（SPR）peak in the visible wavelength range.So by controlling the shape of the gold particles,which can be used to adjust its optical properties.The SPR is based on the mechanism of the color change caused by the binding-induced aggregation of gold nanoparticles.The SPR absorbances of gold nanoparticals are extremely sensitive to the size,morphology and external environment of the gold nanoparticles.Uv-visible spectra can be applied to the analysis of biological,chemical,etc.In numerous morphology of gold nanoparticals,anisotropic nanoparticles show unusual and extraordinary physical and chemical properties,especially the multy-branched gold nanoparticles（e.g.,gold nanostars and gold nanoflowers）,their sharp nanoparticles structure make them have stronger SERS effect.Now researchers use them widely for the detection of heavy metal ion of Colorimetric method or SERS.In this thesis,under the conditions of the absence of surfactant and the presence of CTAB,we prepared monodisperse gold nanostars and gold nanoflowers with uniform particle size and morphology by the Seed crystal growth method.Synthesis of multy-branched gold nanoparticles are easy to surface modification,and show the good SERS performance.Then,detection of the aluminum ion with surface functionalized gold nanostars.The concrete content is as follows:（1）the second chapter,by changing the amount of the gold seeds and sodium citrate in the growth solution,preparation of special morphology of gold nanoparticles-gold nanostars with controlled particle size at room temperature;And emphatically explores the influence about the morphology,size and the optical properties of the gold nanoparticals,which results from the quantity of gold seeds.And explores its application prospect in SERS spectra analysis.（2）In the third chapter,by changing the amount of gold seeds and reactants in the growth solution,under the conditions in the presence of the surfactant-CTAB and 30℃,synthesis of the special morphology of gold nanoparticles-gold nanoflowers with controlled size.And explores its application prospect in SERS spectra analysis.（3）in the fourth chapter,functionalized gold nanoparticles with 3-mercapto propionic acid（MPA-AuNSs）as the base,which can be used in the quantitative detection of Al³⁺ with Colorimetric method.In the testing process,with the increase of concentration of Al³⁺,Uv-vis absorption spectra at 597 nm absorption peak gradually disappear,and the absorption value of 799 nm is higher and higher.And excessive concentration of Al³⁺ will lead to precipitate completely and all Uv-visible absorption peak will disappear.In this chapter,we explore deeply the sensitivity and selectivity of detection of Al³⁺ through the experiment.The basement in the detection of Al³⁺ showed high sensitivity,and the detection limit just is 1.2μM.And by comparing the different concentration of various metal ions(Al³⁺,Cd2+,Co2+,Cu2+,K+,Mn2+,Ni2+,Pb2+,Zn2+),it is concluded that individual metal ion will not produce interference to the test.So it proves that the probe could detect Al³⁺ Specifically.MPA-AuNSs can have widespread application in the practical in real life,such as detection of Al³⁺ in the drinking water or food.