The Fabricaiton And Investigation Of Gold Nanoparticle Chain Arrays With Different Interparticle Separations

Due to the collective oscillation of free electrons in the noble metallic nanoparticles,localized surface plasmon resonances can be excited in this case.By adjusting parameters such as particle shape,size,and refractive index of the surrounding medium,the localized surface plasmon resonances can be tuned to a wide wavelength range;at the same time,due to the effect of charge aggregation,there is a strong local field enhancement,these properties make noble metallic nanostructures have broad application prospects in the field of micro-nano photonic devices.Especially when the noble metallic nanoparticles are approaching to each other,a strong surface plasmon coupling will occur,thereby forming a richer optical response,such as the formation of bonding and anti-bonding resonances due to the plasmon hybridization;the local field strength can be further increased in the nanoparticle interval.Therefore,how to construct a system with strong plasmon coupling is a hot research topic.The PDMS fold template self-assembly method is an effective method for preparing noble metal nanoparticle chain arrays,in which the particles in the chain are closely packed together,which can greatly enhance the surface plasmon coupling,so increase Raman Scattering,high-sensitivity sensing and other fields have been widely used.However,the spacing between nanoparticles in this coupling system depends only on the thickness of the coated molecular layer on the particles,so the spacing is only 1 to 2 nanometers,which makes the local resonance of the coupling chain system produce a large amount compared to a single nanoparticle.Red shift,its resonance peak position is difficult to adjust to the visible light band;in addition,when this chain array and fluorescent molecules constitute a hybrid system,the close distance between the two will also cause the effect of fluorescence quenching.How to effectively adjust the distance between the nanoparticles in this chain array system is the key to expanding its application.In order to solve the above problems,a method for preparing bovine serum albumin and silica-coated gold nanoparticle chain array based on PDMS ordered fold template was proposed in this paper.Relative to the coating polymer layer precious metal nanoparticle chain array system,the innovation of this method is that the spacing between the nanoparticles in the prepared chain array can be effectively adjusted by changing the thickness of the silica layer.Therefore,the coupling effect of the surface plasmon can be effectively adjusted,and it is expected to be used as a carrier for the fluorescent group and the spacer to control the distance between the metal core and the fluorescent group.At the same time,compared to the physical etching method of preparing nanoarrays by conventional etching methods,this method can solve the high cost,processing time-consuming and other issues.The specific work involves the following three aspects:(1)The influence of the manufacturing process of PDMS ordered fold template and the experimental conditions on the fold cycle and hydrophilicity were studied.By changing the experimental conditions,periodic sinusoidal folds with a period ranging from 0.66?m to 2.44?m were obtained.It was also found that increasing the time or power of the Plasma treatment will increase the period of the PDMS fold template,while increasing the Plasma treatment air pressure and PDMS stretching ratio will reduce the period.Among them,the fold cycle is the most sensitive to the change of air pressure in Plasma treatment.The increase of the second Plasma treatment time can not only improve the hydrophilic state of PDMS folds but also reduce the fold depth,but it does not have a significant effect on the fold cycle.(2)The growth of gold nanoparticles and the coating process of bovine serum protein and silica shell were studied.By changing the volume of the added gold seed solution and oxidative etching solution,monodisperse,highly uniform gold nanosphere particles with diameters ranging from 30 nm to 95 nm were prepared,and the plasmon resonance peak position was red-shifted from524 nm to 563 nm.Controllable adjustment of the thickness of the silica shell from 6nm to 12nm is achieved by changing the volume of TEOS solution in the reaction system and the volume of deionized water added,providing control of the spacing of nanoparticles in the array and modulation of the coupled resonance peak position The possibility.(3)Self-assembly of gold nanoparticles based on PDMS fold template is realized.It shows the self-assembly of nanoparticles after surface functionalization of gold nanoparticles with two different materials(BSA and SiO₂).Among them,BSA can provide a particle interval of about 2 nm for gold nanoparticles,and SiO₂can provide a particle interval of 6 nm-12 nm,which lays the foundation for plasmon resonance coupling tuning.