Studies On The Interaction Of Iodine And Gold Or Silver Nanoparticles By Localized Surface Plasmon Resonance Light Scattering Imaging

Noble metal nanoparticles,especially gold（AuNPs）and silver nanoparticles（AgNPs）,have localized surface plasmon resonance（LSPR）optical scattering properties that owing to their own and their related environment,thus,they have become very useful optical probes.Therefore,it is meaningful to study not only the LSPR theory of the nanoparticles,but also the applications in the research of chemical reactions.So far,the light scattering analysis of gold and silver nanoparticles has been applied in various aspects of biochemical reactions,such as analysis and detection,biological imaging,monitoring of chemical reactions,cancer cell imaging etc.The reactions between iodine and gold or silver nanoparticles is a classical one in recent years that studied by researchers on all research field.In this work,we do our reaearches on the gold and silver nanoparticles to study the interaction of gold and silver nanoparticles with iodine on a single nanoparticle level using the dark-field imaging technology.The research concent are as follows:1.In situ monitor the reaction of single silver nanoparticles with iodine.Iodine has played excellent roles in the sysnthesis and morphology controlling of metal nanoparticles.As silver and gold nanoparticles have different properties,the actions between siver and gold nanoparticles are also distinct.This paper took silver nanoparticles as the reaction object and investigated the interaction between iodine and silver nanoparticles at the single nanoparticle level.After exposure of silver naoparticles to etching solution,the scattering light of silver single silver nanoparticles exhibited intensity decreasing and color changes from blue to green The results showed that silver nanoparticle maybe transformed to Ag@AgI composite nanoparticles.Using a commonly used software IPP,the scattering light colour and intensity of a single nanoparticle were coded and digitized with the RGB system a new method for analysing the interaction of single silver nanoparticles and iodine was established.The complex substance exhibited an absorption band peak at 422 nm,which was an exciton absorption peak.Further characterizations by scanning electron microscopy（SEM）,dark-field microscopic（DFM）,and energy-dispersive X-ray spectroscopy confirmed the generation of Ag@AgI.The study is of great significance to understand the reaction between silver nanoparticles and iodine.2.In situ monitor the etching process of single gold nanoparticle.Real-time monitoring of reaction processes is helpful for understanding the reaction mechanisms.In this study,we investigated the etching mechanism of gold nanoparticles by iodine on a single-nanoparticle level because AuNPs have become important nanoprobes with applications in sensing and bioimaging fields owing to their specific localized surface plasmon resonance properties.By using a scattered-light dark-field microscopic imaging（iDFM）technique,the in situ KI/I₂-treated etching processes of various shapes of AuNPs,including nanospheres（AuNSs）,nanorods（AuNRs）,and nanotrigonal prisms（AuNTs）,were monitored in real time.It was found that the scattered light of the different shapes of AuNPs exhibited noticeable color changes and scattering light intensity decreas upon exposure to the etching solution.Combining SEM with dark-field microscopy technology,further changes in morphology of gold nanoparticles after the reaction were determined.The date obtained from elemental analyser and atomic force microscopy confirmed that the scattering spectra showed obvious blue-shifts with decreasing scattered intensity during the etching process owing to the oxidation of gold atoms into [AuI₂]–.Both finite-difference time-domain（FDTD）simulations and monitoring of morphological variations proved that the etching was a thermodynamic-dependent process through a chamfering mechanism coupled with layer-by-layer peeling,resulting in isotropic spheres with decreased particle sizes.3.Light scattering imaging of the intereaction of single silver coated gold nanorods（Au@Ag NRs）with iodine.Recently,alloy have raised much interest in the field of nanomateriels because of their distinctive electrial and optical properities,especially LSPR properities.Firstly,we synthesized Au@Ag NRs,after exposure of Au@Ag NRs to the iodine solution,the scattering light of all single Au@Ag NRs exhibited noticeable changes from orange red to blue under DFM,sugguesting the formation of Au@Ag@AgI NRs.Using the RGB colour systerm,DFM and EDS,we could be further speculated the formation of Au@Ag@AgI NRs,which could be more conducive to the study of relationship of alloy and iodine.In summary,we in stiu monitored the interaction between iodine and gold nanoparticles or silver nanoparticles using dark-field light scattering imaging technology that based on the localized surface plasmon scattering properties of the nanoparticles.The goal was aim to clarify the mechanism of reaction.The chemical reaction process of a single nanoparticle were real-time monitored.