High Temporal-Spatial Superlocalization Microscopy For Single Particle Imaging With Optical Anisotropy

Taking advantages of their unique physical and chemical properties,noble metal nanoparticles have wide application prospects in the fields of nano laser,materials science,biochemical sensing and diagnostic medicine,etc.In order to fully regulate the properties of nanoparticles and elucidate the process of biochemical reaction,it is essential to study the interaction between surrounding environment and single nanoparticle,as well as fully understanding the influence of the shape,size,composition of the nanostructure on its photoelectrical properties,at single particle level.Single-particle microscopy imaging technology based on localized surface plasmon resonance(LSPR)has shown unique advantages in this study.Here,the progress we achieved in this research are as follows:First,we used a dark field microscope with high signal-to-noise ratio and high sensitivity to image single particles.The intensity of the scattered light of the gold nanorods was periodically changed with the change of the polarization direction of the incident light.On this basis,we established a super-localization tracing technology with a temporal resolution of 10ms and a spatial localization precision of 20nm,which allows for simultaneously tracking single particle in spatial-temporal-frequential domain.We utilized this methodology to evaluate the rotational Brownian motion of gold nanorods and study the effects of fluid viscosity on the translational and rotational motion of nanorods.It is proved that the single particle tracing technique we constructed is fully capable of monitoring the changes of environmental media by measuring the motion state of single particle.With the above super-localiztion tracing technique,we selected gold nanorods with good optical stability and strong scattering signals as motion probes to study the molecular recognition which occurring near the surface of the gold nanorods by accurately tracking the changes of single particle motion behavior.We successfully monitored the transient molecular recognition of biotin modified gold nanorods and streptavidin coated glass slides,while dynamic changes between the transition state and steady state in molecular recognition were observed.This technique of capturing molecular recognition reactions at the single particle level improves our understanding of the dynamic process of molecular recognition and helps us to study the dynamic behavior of single molecules hidden under the overall measurement method.Afterwards,we built a random scattering superlocalization microscope to investigate the near-field electric field distribution of plasmonic materials.In the imaging process,only a few scattered photons with elastic collisions on different parts of the nanostructure are collected for each shot,and the precise position of each diffraction spot is extracted by single molecule localization method.After a series of imaging cycles,the optical image is reconstructed using the superposition method previously constructed,and simultaneously obtained the near-filed radiation patterns.Using this random scattering superlocalization microscopy imaging technique,the lateral resolution achieved for goldnanowire is 3-4 times higher than the traditional dark field microscope.The reconstructed localization distribution probability image allows us to visualize the enhanced local fields near the nanowire and investigate the plasmon resonance mode in far field imaging.