Study On The Electrical Properties And Local Surface Plasmon Of Macroscopic Gold Nanoparticle Assembly

Thanks to good biocompatibility,electrical and optical properties,gold nanoparticles have been playing an important role in biomaterial research.With the development of gold nanoparticles in the field of biomedical applications,it has become a key problem to study the specific assembly structure and properties of gold nanoparticles,which is expected to play an important role in the development of new bioelectrometer devices in vivo.The assembly and electromagnetism properties of macroscopic uniform dense films of gold nanoparticles have been carried out as follows:First,gold nanoparticles with good monodisperse,uniform particle size and good reproducibility were synthesized by sodium citrate reduction.Then,the gold nanoparticles films with different layers were assembled by layer-by-layer self-assembly method.A significant alteration of the electric impedance occurred with increasing amounts of assembled layers.This alteration can be explained by the shift in the electron-transport mechanism from the hopping model to the percolation model.This increased conductivity leads to the emergence of eddy currents when the assembled films of gold nanoparticles are subjected to alternating magnetic fields,and consequently induces thermogenesis of the films because of Joule heating.Furthermore,this effect was employed for the controlled release of drugs by implanting assembled colloidal gold cores into a DOX-loaded hydrogel.As an alternating magnetic field has the advantage of being able to penetrate through the entire human body(as opposed to light),the thermogenesis of gold nanoparticles under an alternating magnetic field will greatly widen the in vivo application of the thermal effect of gold nanomaterials.Then,through the structure transformation,the helical gold nanoparticle metamaterial film was formed by layer-by-layer self-assembly method.It is found that there is a significant resonance peak in the microwave frequency range,which is obviously different from the resonant peak of the spiral material composed of macroscopic metal or sputtering method.It is indicated that there is a significant difference between the metamaterial structure of the gold nanoparticles and the direct accumulation of gold atoms.On the basis of this,the microwave resonance properties of helical metamaterials with different degrees of bending were studied.The results showed that the bending angle and the position of the resonant peak show a positive correlation.Therefore,study on the relationship between the electromagnetic response and the assembly structure of the helical nanoparticle metamaterials in the microwave frequency band and the special electromagnetic properties based on the nanomaterials to control the macroscopic microwave resonance phenomena lay a certain foundation for the future development of new biological materials.This paper focuses on the change of the collective conductive properties of gold nanoparticles caused by assembly,and studies the response of the assembly structure in the middle and low frequency and high frequency electromagnetic fields,which provides a basis for future biomedical application based on gold nanoparticle assembly.