Surface Plasmonic Resonance Based Microscopy For Biochemical Analysis

The optically excited collective electronic oscillations through the interaction between metals and incident light form the propagating surface plasmon resonance (SPR) existing at the interface between any two materials where the real part of the dielectric function changes sign across the interface (e.g. a metal-dielectric interface). Recently SPR-based techniques have been widely used in the fields of life science and microscopy. Based on these background, this dissertation focus on the appliction of SPR-based microscopy techniques for bioanalysis. The main contents are as follows:1. Single Gold@Silver Nanoprobes for Real-Time Detection of Superoxide Radicals.Superoxide radicals (O2·-) is one member of the Reactive Oxide Species (ROS), which is vital for recognizing cell metabolism, e.g. differentiation, growth and apotosis. Thus high-sensitive and high-specific sensing of ROS, especially O2·-, are attractive in biochemical researches. This work describes a multimodified core-shell gold@silver nanorods, which have localized SPR scattering signal in the near infrared region. This nanorods were eteched by O2·-and gave a notable wavelength change in the plasmon resonance scattering spectra. Both the experimental and simulated results suggested the wavelength change rate correlated well with O2·-level. This response enabled its application in real-time in situ quantification of O2·-2. Single Gold@Silver Nanoprobes for Real-Time Tracing the Entire Autophagy Process at Single-Cell Level.This article describes a multimodified core-shell gold@silver nanoprobe for real-time monitoring the entire autophagy process at single-cell level. Autophagy is vital for understanding the mechanisms of human pathologies, developing novel drugs, and exploring approaches for autophagy controlling. A major challenge for autophagy study lies in real-time monitoring. One solution might come from real-time detection of in situ superoxide radicals (O2·-), because it is the main regulator of autophagy. In this work, our proposed nanoprobes were etched by O2℃a nd gave a notable wavelength change in the plasmon resonance scattering spectra. Both the experimental and simulated results suggested the wavelength change rate correlated well with O2·- level. This response enabled its application in real-time in situ quantification of O2·- during autophagy course. More importantly, with the introduction of "relay probe" operation, two types of O2·- regulating autophagy processes were successfully traced from the beginning to the end, and the possible mechanism was also proposed.3. Imaging Local Heating and Thermal Diffusion of Nanomaterials with Plasmonic Thermal Microscopy.Measuring local heat generation and dissipation in nanomaterials is critical for understanding the basic properties, and developing applications of nanomaterials, including photothermal therapy and joule heating of nanoelectronics. Several technologies have been developed to probe local temperature distributions in nanomaterials, but a sensitive thermal imaging technology with high temporal and spatial resolution is still lacking. Here, we describe plasmonic thermal microscopy (PTM) to image local heat generation and diffusion from nanostructures in biologically relevant aqueous solutions. We demonstrate that PTM can detect local temperature change as small as 6 mK with temporal resolution of 10μs and spatial resolution of sub-microns (diffraction limit). With PTM we have successfully imaged photothermal generation from single nanoparticles and graphene pieces, studied spatiotemporal distribution of temperature surrounding a heated nanoparticle, and observed heating at defect sites in graphene. We further show that the PTM images are in quantitative agreement with theoretical simulations based on heat transport theories.