Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session G04: Coherent Nonlinear Optical Microscopy IIFocus
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Sponsoring Units: DCP DSOFT DPOLY DLS Chair: Adrian Pegoraro, Univ of Ottawa Room: 109 |
Tuesday, March 3, 2020 11:15AM - 11:51AM |
G04.00001: Nonlinear Pump-Probe Microscopy Improves Early Detection of Metastatic Melanoma Invited Speaker: Warren Warren More people die from melanoma after a Stage I diagnosis (localized) than after a Stage IV diagnosis (distant metastatic disease), because the tools available to clinicians do not readily identify which early-stage cancers will be aggressive. We pursue an alternative approach, complementary to conventional histopathology, based on ultrafast pump-probe microscopy. Melanocytes, the neoplastic cells in melanoma, produce a brown to black colored pigment melanin. Analysis of the electronic and vibrational dynamics of melanin with ultrashort laser pulses reveal information like type (pheo, DHI or DHICA eumelanin) and state of aggregation, for example. We use these insights to evaluate primary tumor biopsies with the goal to distinguish between localized melanoma (without metastases) and melanoma that developed metastatic disease. In this talk we focus on our efforts of translating pump-probe microscopy into clinics and our current status on detection of metastatic disease of melanoma. |
Tuesday, March 3, 2020 11:51AM - 12:27PM |
G04.00002: Visualizing molecular structure and function in soft matter using coherent Raman imaging Invited Speaker: Sapun Parekh Structure-function relationships define the how molecular processes give rise to macroscopic observables. In this talk, I will present an overview of our recent work using nonlinear vibrational spectroscopic imaging to reveal unique structural-function relationships in polymeric soft matter systems. We have used this imaging technology to map protein structure in fibrin biopolymer networks (that lie at the heart of blood coagulation) and demonstrated that fibrin biopolymers change structure in a spatially heterogeneous manner when exposed to tensile, but not shear, loads. This result hints at a unique self-regulating mechanism via a direct biophysical feedback loop in a physiological context. In another project measuring real-time water transport, we have shown that under-coordinated microscopic water transport and macroscopic proton transport are related in nano-structured polymer fuel cell membranes. From these data, we have proposed a strategy to boost efficiency in fuel cell membrane materials. |
Tuesday, March 3, 2020 12:27PM - 12:39PM |
G04.00003: Correlating Multiphoton-Absorption-Induced Luminescence (MAIL) with Morphology in Noble-Metal Nanostructures Anna Grafov, Xiaoying Lin, Farah Dawood, John T Fourkas The optical properties of nanostructured noble metals differ drastically from those of their bulk counterparts due to surface plasmon (SP) resonance. When incident light couples with the SPs of a noble-metal nanoparticle, it gives rise to strong, localized electromagnetic field enhancement. In particular, surfaces with high curvature experience especially strong field enhancement. Silver and gold SP absorption cross sections lie in the visible region, which make nanostructures of these metals ideal for studying optical phenomena. Multiphoton-absorption-induced luminescence (MAIL) is a nonlinear optical phenomenon that involves ultrafast pulses of light impingent on a nanostructured surface. The SP field enhancement allows for more efficient multiphoton absorption, and highly-efficient, broadband luminescence over the visible spectrum is produced as a result. We examine how the morphologies of noble-metal nanostructures correlate with their MAIL signals. Specifically, we focus on silver nanodendrites, synthesized from galvanic displacement reactions, and gold nanorings and nanotriangles, grown through colloidal synthesis. The absorption order, intensities, and spatial distribution of MAIL signals are examined for different morphologies. |
Tuesday, March 3, 2020 12:39PM - 1:15PM |
G04.00004: Stimulated Raman scattering spectroscopic optical coherence tomography Invited Speaker: Francisco Robles Stimulated Raman scattering (SRS) enables fast, high-resolution imaging of chemical constituents important to biological structures and functional processes in a label-free manner. While this technology has shown remarkable potential, acquisition of SRS signals remains largely limited to point scanning at a few Raman bands. To overcome this limitation, we take advantage of the fact that SRS is a coherent process and can thus be integrated into a single platform with spectroscopic optical coherence tomography (SOCT). SOCT is an extension of OCT that leverages the broadband nature of low-coherent light sources, along with advanced digital signal processing methods, to simultaneously obtain three-dimensional spatial and spectral information, but SOCT has very limited endogenous molecular targets. Thus, the combined approach, termed SRS-SOCT, overcomes limitations of both individual methods and achieves fast, volumetric, and highly sensitive label-free molecular imaging. Here we will present a theoretical framework for SRS-SOCT, discuss its advantages and limitations, and show experimental results from excised tissues. |
Tuesday, March 3, 2020 1:15PM - 1:51PM |
G04.00005: Spectroscopic Fourier-Transform Coherent Raman Microscopy Invited Speaker: Marcus Cicerone Spectroscopic coherent Raman imaging (CRI) methods allow label-free, chemically secific imaging of materials and biological systems, and are opening up many exciting possibilities for understanding phenomena in these systems. I will briefly introduce spectroscopic CRI, specifically broadband coherent anti-Stokes Raman scattering (BCARS) , discussing key features required to make these methods practical, current impedements to improvements in speed and sensitivity, and new approachs we are taking to overcome these impedements. I will also present BCARS imaging results that have provided physical insights into biological processes on cellular and organism levels. |
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