Study On The Morphology And Properties Of Gold Nanostars Controlled By Light Irradiation

Gold nanostars are multi-branched nanoparticles with tip structures.Nanostars have excellent photoelectric properties,good biocompatibility and low toxicity,which opens broad application prospects in biomedical field.By changing the morphology of gold nanostars to manipulate their optical properties,it not only makes them ideal for surface-enhanced Raman scattering(SERS)substrates,but also enhances their photothermal properties and play a better role in biomedical applications.However,the current methods for the branch-length control of gold nanostar is limited to the chemical method,which is mainly about adjusting the concentration of reactants.As a result,the chemical methods not only have complicated operation steps,but also difficult to control the quality of products.In this paper,we propose a method to prepare gold nanostars by light irradiation,and to control the morphology of gold nanostars.In the regulation of gold nanostar morphology,this experiment mainly through the regulation of branch-length of the gold nanostar,to achieve its size control.On the basis of the "one step growth" method,the light irradiation was added to the growth process.The experimental results showed that the branch of the nanostars prepared with light irradiation is shorter in length than those prepared without light irradiation.By changing the wavelength of the irradiated light,the length of the branches can be controlled.Based on the experimental and theoretical deduction,the theoretical model is put forward.In the growth process of gold nanostars,the branches grow first and then become shorter.In order to study the optical properties of gold nanostar that prepared by light irradiation method,the experimental and theoretical calculations were carried out from two aspects.On the one hand,to explore the light-heat conversion capacity of the gold nanostars with different branch-lengths.By measuring and calculating the photothermal conversion efficiency,it is concluded that the shorter the branch is,the higher the photothermal conversion efficiency is.And the time domain finite difference method(FDTD)is used to simulate and verify the experimental results.On the other hand,the SERS activity of gold nanoparticles was investigated,which was proved that the gold nanoparticles prepared by light irradiation still had excellent SERS performance.The gold nanoparticles prepared by light irradiation have higher photothermalconversion efficiency and excellent SERS activity.They have a wider application prospect in biomarkers,imaging monitoring,and phototherapy of tumor.