Construction And Optical Properties Of Structure-Polarization Coupled Nanomaterials

Noble metal nanomaterials have attracted the unique attention in nanoscience and nanoengineering due to their structurally tunable polarization properties,and have been widely used in chiral detection,optical sensing and cell imaging.When light is irradiated onto the surface of noble metal nanomaterials,the surface free electrons of the nanomaterials exhibit strong local surface plasmon resonance(LSPR)effect.This effect is highly dependent on the structural information of noble metal nanomaterials(such as the size,morphology and surface properties of nanomaterials,etc.),which could be precisely tuned via strategies of assembly and morphological regulation.In addition,certain noble metal nanomaterials exhibit polarization-dependent behaviors as the nanomaterial structure changes.These behaviors are relevant for resolving the optical information of nanomaterials,promoting the development of optical advanced technology,and probing the origin of life.However,during the synthesis process of noble metal nanomaterials,the addition of surfactants can lead to uneven surface charge distribution,thereby affecting the polarization optical properties of the material.In addition,some optically active chiral noble metal nanomaterials will generate circular dichroism(CD)under the excitation of left-handed and right-handed circularly polarized light,thus realizing the detection of circularly polarized light by chiral materials.But,the mechanism of chiral signal transfer,amplification and anomalous inversion caused by structural and interface changes of chiral noble metal nanomaterials is still unclear.Based on this,this paper conducts the following research and exploration.(1)Anisotropic gold nanodimer probes(Au HDs)were designed and synthesized to monitor their polarization characteristics and endocytosis kinetics under dark field linearly polarized light.The constructed Au HDs probes have dumbbell-shaped conformation and homogeneous surface physicochemical properties,allowing us to obtain the anisotropic scattering characteristics and corresponding polar Angle information under a dark field microscope(DFM)in high throughput,thus studying the angle-dependent polarization behavior of the probes at the single-particle level.In addition,Au HDs probes have good biocompatibility and stability,which can monitor the process of cell internalization under DFM.By using DFM and CBA-assisted single particle tracking(SPT)techniques,we systematically investigated the rotational motion patterns of Au HDs during internalization.The results of rotational dynamics analysis showed that Au HDs undergo a complex and restricted kinetic behavior during endocytosis and proceed in a predominantly unilateral rotational motion pattern when they crossing the cell membrane.This study provides a new idea for the development of anisotropic optical nanoprobes and the development of precision medicine.(2)A surfactant(CTAB)mediated chiral core-shell nanostructure(Ag NP-Cys@Ag)was precisely synthesized to study its chiral optical activity under circularly polarized light.The construction of chiral core-shell structure could perfectly realize the effect of chiral signal transfer and signal amplification,so as to enhance the absorption difference of the chiral system for the circularly polarized light.In addition,the addition of CTAB not only modulated the interfacial assembly mode of the core-shell structure,but also induced systems with different chiral optical activities,which finally achieved the chiral signal flipping of the core-shell structure.The theory and experiment proved that the flipping phenomenon came from the different binding ways between chiral molecules and noble metal nanomaterials.Meanwhile,the chiral signal of the Ag NP-Cys@Ag core-shell structure was independent of its core nanostructure,but only influenced by the outer nanostructure.This regulation idea has changed the limitation that traditional chiral nanomaterials only have one chiral center,which required the addition of corresponding chiral molecules to achieve chiral signal symmetry,and also provided a new ideas for novel optical applications of chiral nanomaterials and precise studies of circularly polarized light.