Bulletin of the American Physical Society
2018 Annual Meeting of the APS Four Corners Section
Volume 63, Number 16
Friday–Saturday, October 12–13, 2018; University of Utah, Salt Lake City, Utah
Session E06: BIO2: Bioimaging and Detection |
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Chair: Brian LeRoy, University of Arizona Room: CSC 210 |
Friday, October 12, 2018 1:30PM - 1:54PM |
E06.00001: Developing Red Fluorescent Proteins – Tools and Strategies Invited Speaker: Sheng-Ting Hung Fluorescent proteins have become an indispensable tool for biological and biomedical research owing to their genetic encodability. Red Fluorescent Proteins (RFPs) are advantageous for live-cell imaging due to low optical attenuation and phototoxicity for excitation beyond 550 nm. We are devoted to developing novel strategies and tools to improve RFPs with multiple desirable photophysical properties. The most commonly adopted strategy to enhance molecular brightness of RFPs is to reduce the nonradiative decay pathways, which lengthens the excited state lifetime and possibly reduces photostability due to the longer time spent in the excited state. We propose to simultaneously improve molecular brightness and photostability of RFPs by increasing the radiative decay rate. We also develop microfluidic sorters capable of selections based on multiple photophysical properties. We use these instruments to accelerate and visualize the evolution of RFPs towards desirable photophysical properties for library sizes on the order of 106 mutants. |
Friday, October 12, 2018 1:54PM - 2:18PM |
E06.00002: Sequential super-resolution imaging using DNA strand displacement Invited Speaker: Keith Allan Lidke We describe a simple new method for super-resolution of imaging of many different structures/proteins in the same cell using a sequential imaging strategy. The simple optical setup needs no spectrometers, beam splitters or channel registration. Briefly, antibodies are pre-conjugated to a ‘protector’ strand of ssDNA. After cellular labeling and before imaging, a complementary ‘template’ strand, which is labeled with the dye, is added to the sample to bind and label the protector. After imaging, a third ‘invader’ ssDNA is introduced that gains a toe-hold on the template, and competes it off the antibody-protector complex. Orthogonal sets of protector\template\invader are used to label different cellular structures. All antibody labeling is done at once, before imaging. Both the template binding and invader action only require about ~ 1 minute, allowing quick progression through the different structures. We demonstrate the concept by performing dSTORM imaging on several different proteins in a single cell. The concept is easily extended to multiple proteins and could be used for other SR techniques such as STED and SIM. |
Friday, October 12, 2018 2:18PM - 2:30PM |
E06.00003: Precisely Localizing Wavelength Sensitive Point-Spread Functions Engineered With a Silicon Oxide Phase Plate Jason T. Martineau, Rajesh Menon, Erik M. Jorgensen, Jordan Gerton Recently point-spread function (PSF) engineering has made important contributions to single molecule localization microscopy (SMLM). PSF engineering has allowed scientists to encode information into the PSF in addition to position. One drawback of the current work is that it typically uses expensive polarization dependent spatial light modulators to modify the phase of the signal. Here, we introduce a simple silicon oxide phase plate that, when placed in the Fourier plane of a microscope, makes the PSF very sensitive to wavelength. We have used this engineered PSF (ePSF) to identify different species of fluorescent nano-spheres based only on the form of their respective PSFs. This experiment was done on a home-built microscope. Both the spatial and wavelength localization precisions measured from this experiment were in the single nanometer range for ~5000 photons. We have also used this same phase plate to do two-color SMLM. This imaging was done on fixed B2SO cells. We were able to resolve microtubules to 50 nm. This experiment was done on a commercially available microscope, the Vutara 352. In the future we aim to use our phase plate to look at small spectral shifts in SMLM dyes caused by environmental conditions, such as pH, within the cell. |
Friday, October 12, 2018 2:30PM - 2:42PM |
E06.00004: A Convolutional Neural Network for Cancer Detection via Optical Scattering Classification Mason Acree, Christopher Berneau, Portia Densley, Daniel Blumel, Quin Neilson, Shane Gunnerson, Gunnar Jensen, David Erickson, Ryan Condie, Russell Massey, Kyle Kennington, Alex Johnson, Ryan Bevan, Vern Hart In the early stages of most cancers, changes begin to occur at the cellular level as nuclei elongate and mitochondria cluster unevenly. As these organelles are responsible for much (>40%) of the optical scattering which occurs in a cell, changes in morphology and structure can significantly affect the resulting optical signature. Variations in the physical properties of different cancer types lead to a distinct scattering profile unique to each disease. In this study, optical scattering patterns were investigated from five different cancer cell lines, which were irradiated in vitro with a near-infrared diode laser. The resulting patterns were collected with a CMOS beam profiler and used to train a convolutional neural network. Differences in these profiles were significant enough to allow successful classification by the neural network. After being trained with a set of augmented images from each cancer type, the network distinguished cell lines with an accuracy of up to 98.5%. The accurate classification of these patterns at low concentrations could lead to the early detection of cancerous cells in otherwise healthy tissue. |
Friday, October 12, 2018 2:42PM - 2:54PM |
E06.00005: Simulating Microgravity and Space Radiation with a Rotary Cell Culture System (RCCS) Alexandra Nelson, Lori Caldwell, Eryn Hanson, JR Dennison, Elizabeth Vargis A Rotary Cell Culture System (RCCS) has been developed to simulate the combined effects of microgravity and radiation on living cells. The RCCS will be used to study these effects on mice, cardio muscle and skeletal cells to understand effects of long duration missions in space. A RCCS has a rotating cylindrical chamber containing a solution of cells suspended in a viscous fluid. To simulate microgravity the chamber is rotated, and the cells fall through the fluid reaching terminal velocity. However, as the cells fall the chamber rotates resulting in a continuous state of “free fall”. During this free fall, the cells experience very little net force, as viscous drag and centripetal forces are adjusted to counter balance gravitational forces, therefore simulating microgravity experienced in space. The new system incorporates 3-6 rotating chambers which can be inserted into the Space Survivability Test (SST) Chamber allowing simultaneous exposure to a penetrating beta radiation from a Sr90 source. |
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