Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session J26: Multimodal Optical Trapping/Microscopy/Spectroscopy of Living MatterFocus
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Sponsoring Units: DBIO DSOFT Chair: Minjoung Kyoung, University of Maryland Baltimore County (UMBC) Room: 403 |
Tuesday, March 3, 2020 2:30PM - 3:06PM |
J26.00001: Development and Application of Three-Dimensional Multi-Resolution Imaging Invited Speaker: Haw Yang A complex system contains dynamics that span several orders of time scales over several length scales that are spatially non-homogeneous. Examples include virus (or nanoscale drug delivery vehicle) uptake by a living cell and particle percolation through a dynamically reconfiguring medium. The spatial heterogeneity and the lack of separation of time scales are such that ensemble-averaged experimental approaches tend to miss the mechanism-defining steps in such processes. In this presentation, we explain how a multi-resolution approach helps to elucidate dynamics in complex systems. We then describe the basic ideas and implementations for these types of instrument. Applications to biological and materials systems will also be discussed. |
Tuesday, March 3, 2020 3:06PM - 3:18PM |
J26.00002: Avalanching Upconverting Nanoparticles for Super Resolution Imaging Emma Xu, Changhwan Lee, Kaiyuan Yao, Bruce Cohen, Emory Chan, Yung Doug Suh, P. James Schuck Photon avalanche (PA) is a photon energy upconversion excitation mechanism. It enables nonlinear dependence on excitation power, which is a key factor for various applications in photon science. One exciting application is that it suggests a possible approach to super-resolution imaging with a simple confocal microscope system. Here, we introduce avalanching upconverting nanoparticles (AUCNPs), NaYF4 nanocrystals doped with Thulium ions. The presence of PA was verified by time-resolved photoluminescence measurement. Upon the exitation of 1064nm laser, the resolution of 2-dimensional photoluminescence map was resolved to 90nm as a result of high nonlinearity, more than 4 times of diffraction-limited imaging resolution. AUCNPs are thus a promising new method for super resolution bioimaging. |
Tuesday, March 3, 2020 3:18PM - 3:30PM |
J26.00003: Mechanical unzipping of DNA molecules in parallel using nanophotonic tweezers Fan Ye, James T. Inman, Michelle D. Wang Optical trapping is a valuable technique widely used in biological and materials sciences, covering size scales ranging from the single molecule to the cellular level, and force scales from sub piconewton (pN) to tens of pN. In the past decades, the rapid development of nano techniques has bolstered the emergence of nanophotonic tweezers. The ability of nanostructures to direct and confine light beyond the diffraction limit enables miniaturized, on-chip devices with abilities beyond microscope-based optical traps. Our lab has developed and implemented such an on-chip device - the nanophotonic standing-wave array trap (nSWAT) [1,2]. The nSWAT is based on Si or Si3N4 waveguides and allows for controlled and precise manipulation of trapped single biomolecule (such as DNA) arrays via microparticle handles. Here, we present an nSWAT that achieves manipulation forces large enough to mechanically unzip an array of DNA molecules at room temperature. This benchmark achievement is another step closer to the full realization of nanophotonic tweezers’ capabilities, promising increased accessibility and expansion of these platforms to a wide range of biological and biomedical research topics. |
Tuesday, March 3, 2020 3:30PM - 3:42PM |
J26.00004: A Simple Approach to Optical Trapping Analysis Javier E Hasbun, James Howard, Zachary Patterson-Goss, Suvranta Kumar Tripathy Optical tweezers provide a noninvasive approach for detecting pico-newton forces with nanometer level spatial resolutions [1]. We have developed a simplified model of an optically trapped micron-sized particle using a modified version of a numerical approach [2]. The equations of motion associated with the model assume a low Reynolds number and the stochastically simulated bead behavior is carried out in two dimensions. The passive power spectrum analysis and equipartition theorem analysis confirm the agreement between simulated and experimental data. Based on the experimental and simulation analysis this simple approach can be used to gain information about bead's confining environment such as local temperature and viscosity. |
Tuesday, March 3, 2020 3:42PM - 3:54PM |
J26.00005: Bacterial proteomes are predictable from cellular Raman spectra Ken-ichiro F Kamei, Koseki J Kobayashi-Kirschvink, Hidenori Nakaoka, Yuichi Wakamoto Whole-cell Raman spectra reflect its molecular composition and allow us to distinguish cellular states in a label-free and non-destructive manner. Previously, we showed that in S. pombe and E. coli, cellular Raman spectra and transcriptomes were linked quantitatively and that the transcriptomes could be inferred from Raman spectra (Kobayashi-Kirschvink et al., Cell Systems, 2018). We now ask whether Raman spectra could also be connected to other types of omics information. Using quantitative proteome data of E. coli cultured under various conditions (Schmidt et al., Nature Biotechnology, 2016), we show that proteomes can be linked to and reconstructed from cellular Raman spectra. These results suggest that cellular Raman spectra have the potential to unravel and integrate multi-omic states of cells non-destructively, and therefore show great promise in establishing live-cell omics. |
Tuesday, March 3, 2020 3:54PM - 4:06PM |
J26.00006: Live measurements of transcriptional bursting and dynamic gene regulation in early fly embryos Po-Ta Chen, Benjamin Zoller, Michal Levo, Thomas Gregor Gene regulation is intrinsically dynamic: from the microscopic molecular events underlying transcriptional bursting, to genes cross-regulating each other in the context of a genetic network during cellular fate specification. However, knowledge about the transcriptional dynamics of individual genes and the coordinated dynamics of multiple genes in their endogenous context is largely missing. We have developed an optimized 2-photon microscope to measure realtime gene activity in early fly embryos. Our data is highly quantitative making higher-order noise and cross-correlation analysis between multiple simultaneously measured genes possible. Focusing on the gap gene network, we measure endogenous transcriptional activity of individual and multiple genes simultaneously to test a novel time-dependent mathematical framework for transcriptional bursting dynamics and link these to transcriptional states at the network level. We are addressing two questions in particular: What are the dynamics of transcriptional bursting for individual genes, and how are they related to fluctuations of a key regulator? And how do the complex out-of-equilibrium dynamics of individual genes affect the dynamics of the gene regulatory network as a whole? |
Tuesday, March 3, 2020 4:06PM - 4:18PM |
J26.00007: The Origin of Enhanced Enzyme Motility Probed with Optical Tweezers Tian Huang, Jin Tae Park, Hyuk Kyu Pak, Steve Granick Ingenious prior observations show that enzymes in solution display enhanced diffusivity when they catalyze chemical reactions but too little is known about the mechanism. A serious impediment to understanding is that the forces generated during enzyme catalysis are not known. In this talk, we will discuss our effort to measure these forces by using optical tweezers. The displacement probability distribution is enhanced as if the temperature were increased, but the reasons are different. |
Tuesday, March 3, 2020 4:18PM - 4:54PM |
J26.00008: Multimodal microscopy through optimal integration of wide-field and focused-beam laser illumination Invited Speaker: Sang-Hyuk Lee Microscopy can be largely classified into two groups according to how light illuminates specimen: 'wide-field' or 'focused-beam' illumination microscopy. The two microscopy modalities are often integrated into the same instrument, especially for the purpose of combining optical tweezers and fluorescence imaging, with typically employing separate lasers for the two illumination schemes. We have developed a new microscope platform that enables operation of the same laser for the both modalities interchangeably or simultaneously in a way scalable to multiple lasers. In this talk, I will describe the design of the instrument and its application to the multimodal imaging and spectroscopy of biological systems. |
Tuesday, March 3, 2020 4:54PM - 5:06PM |
J26.00009: Near-field optical interferometer for refractive index sensing Abbas Ghaffari, Kevin Gia Do, Robert Riehn Single-molecule sensing for biological physics predominantly uses fluorescence sensing due to the high signal to volume ratio. However, it is far from an ideal detection mode since fluorescence sensing requires the chemical modification of biological molecules. A better alternative is the sensing of refractive index changes due the introduction of a biomacromolecule. Here we introduce a near-field optical interferometer that detects the presence of nanoparticles and proteins by measuring the deflection of a light, and not transmission as commonly performed. |
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