Bulletin of the American Physical Society
2007 APS March Meeting
Volume 52, Number 1
Monday–Friday, March 5–9, 2007; Denver, Colorado
Session B38: Focus Session: Bioinstrumentation and Biophotonic Technologies |
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Sponsoring Units: GIMS DBP Chair: Andreas Mandelis, University of Toronto Room: Colorado Convention Center 501 |
Monday, March 5, 2007 11:15AM - 11:51AM |
B38.00001: Fourier-Domain Biophotoacoustic Sub-surface Depth Selective Amplitude and Phase Imaging of Turbid Phantoms and Biological Tissue Invited Speaker: A novel photothermoacoustic imaging modality utilizing a frequency-swept (chirped) intensity-modulated laser source and coherent frequency domain signal processing (``biophotoacoustics'') was introduced for non-invasive imaging of biological tissues. The developed frequency-domain imaging system takes advantage of linear frequency modulation waveforms to relate depth of tissue chromophores to the frequency spectrum of the detected acoustic response and of a narrow signal detection bandwidth to improve signal-to-noise ratio (SNR). Application of frequency-domain photothermoacoustic (FD-PTA) imaging was demonstrated using turbid phantoms and ex-vivo specimens of chicken breast with embedded absorbing inclusions simulating tumors. [Preview Abstract] |
Monday, March 5, 2007 11:51AM - 12:03PM |
B38.00002: An application of fast response Polarized Light Microscopy Deependra Kantha, David Van Winkle A fast response polarized light microscope was designed based on the algorithm by Shribak et. al (Applied Optics, vol. 42, 3009-3017). A pulsed laser beam was passed through two Pockels cells aligned at different angles with respect to optical axis. The retardance of the Pockels cell was controlled by external switches and power supplies. The electronics circuit in the system allows change of the retardance of the Pockels cell each millisecond for four milliseconds. In four milliseconds, four images of a birefringent sample, formed by different states of polarized light are recorded. The images are added appropriately to calculate retardence amplitude and phase by using codes written in imageJ software. The microscope was used to show the retardance and phase of a rabbit muscle fiber. Recordings were also taken of the contraction of Vorticella convallaria but the changes were too fast to yield retardance images. This type of microscope can be used to study different kinds of biological functions that change on a timescale slower than four milliseconds but faster than two seconds. [Preview Abstract] |
Monday, March 5, 2007 12:03PM - 12:15PM |
B38.00003: Evaluation of optical excitation conditions for ruthenium complex for biosensor optodes Sean Pieper, Zhong Zhong, Kevin L. Lear, Ken Reardon Development of a fiber optic biosensor incorporating genetically engineered enzymes which catalyze chlorinated ethenes in an oxygen-consuming reaction for in situ monitoring of groundwater contaminants motivates optimization of optode excitation conditions. These conditions affect the sensitivity, signal-to-noise, and optode service life impacting the quality of the overall biosensor. Optodes are generally comprised of a fluorophore conjugated with a polymer as a substrate cross linked at the distal end of a fiber optic. We investigate the excitation conditions of tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) chloride (Ru(dpp)3) conjugated with poly(vinyl alcohol) (PVOH) as an optode. A reported advantage of Ru(dpp)3 is that it has no emission spectral shift occurring under varying chemical and environmental conditions. Photostability degradation due to photobleaching of Ru(dpp)3 with PVOH as a substrate is explored by varying the optical irradiance of the fluorophore containing optode. Other issues relating to practical implementation of Ru(dpp)3 as oxygen sensitive biosensors will be discussed. [Preview Abstract] |
Monday, March 5, 2007 12:15PM - 12:27PM |
B38.00004: Two-Photon Microscope with Spectral Resolution Russell Fung, Mike Melnichuk, Anurag Chaturvedi, Devin Gillman, Valerica Raicu Two-photon microscopy has many distinct advantages over other types of microscopy: it is faster, there is no out-of-plane photobleaching, and using near-infrared laser light (to produce visible fluorescence signal) allows deeper penetration into thick samples. We have built a two-photon microscope based on a novel design that uses a diffractive optic, a nondescanned detection scheme and an EM-CCD camera to produce spectrally resolved fluorescence images of samples after only one full scan of the sample and with relatively high speed. Our design is readily extended to incorporate control in the excitation channel through pulse shaping using spatial filtering in the frequency domain. This microscope, in conjunction with Fluorescence Resonance Energy Transfer (FRET) between fluorescent tags, has been used to detect interactions between proteins in various systems including yeast (Saccharomyces cerevisiae) cells. Also, its exquisite sensitivity makes it suitable to spectrally resolve signals from single quantum dots and single molecules. [Preview Abstract] |
Monday, March 5, 2007 12:27PM - 12:39PM |
B38.00005: Exploration of detection sensitivity of biomarker acetone in aqueous samples using cavity ringdown spectroscopy Armstrong Mbi, Chuji Wang Breath acetone is a biomarker for diabetes (Type 1). Currently, high sensitivity breath gas analysis is mainly performed by gas chromatography-mass spectrometry (GC-MC). We are developing a potable ringdown spectrometer for diabetes diagnostics using non-invasive breath gas analysis. The ringdown spectrometer consists of a compact Nd: YAG laser source operating at 266 nm, a atmospheric gas cell of 43 cm in length, a miniature detector, and a data processing section. In this work, the exploration of detection sensitivity of acetone in aqueous samples using cavity ringdown spectroscopy is presented. Pure acetone is diluted in distilled water in different concentrations ranging from 0.5 drop/liter to 8 drops/liter, or 730 ppbv - 12 ppmv in gas phase. The instrument performance using two sampling methods is evaluated. With the mirror reflectivity of 99.98{\%}, the spectrometer demonstrates a detection limit of acetone of 450 ppbv (based on 1-$\sigma )$, which is slightly lower than the threshold number of acetone concentration in normal human breath. Preliminary results from actual breath gases are also presented. [Preview Abstract] |
Monday, March 5, 2007 12:39PM - 12:51PM |
B38.00006: Optofluidic intracavity spectroscopy of single cells in a passive Fabry-Perot resonator Hua Shao, Weina Wang, Susan Lana, Kevin Lear Considerable effort has been devoted to analyzing complex biological systems such as living cells by combining photonic and microfluidic techniques. Cells in biocavity lasers developed by Gourley et al produced rich multimode spectra that multivariate analysis correlated with the cell type. Optofluidic intracavity spectroscopy (OFIS) reported here operates on a similar principles but does not require gain media. It measures transmission spectra of individual cells in a passive Fabry-Perot (FP) cavity. Non-normal incidence identified the relative order of the various transverse modes to verify the applicability of different simplified models of the cavity modes. Distinctive spectral features, including transverse mode spacing and the number of modes were used to differentiate red and white human blood cells, for example. OFIS measurements of canine lymphoma cells produced repeatable transmission spectra. Continuing investigations on the capability of OFIS to distinguish cancer cells will be reported. [Preview Abstract] |
Monday, March 5, 2007 12:51PM - 1:03PM |
B38.00007: Magnetically Directed Cell Co-Localization Edward Felton, Daniel Reich, Yoojin An, Christopher Chen The ability to control the movement and location of biological cells has led to novel approaches to several areas of interest, from tissue engineering to the study of cell-cell interactions. We have introduced ferromagnetic nanowires as a tool for applying forces to cells; their high remanent magnetization allows cells bound to nanowires to be manipulated in low-strength magnetic fields. Micropatterned magnetic structures generate magnetic fields that can precisely guide cells into predetermined positions on substrates in culture, and cells can be restricted to localized areas through chemical functionalization of the substrate. We have used these directed cell assembly techniques to organize cells into a variety of patterns with a single cell type, and have extended its utility to include two cell types. We have created regular arrays of cells in which heterotypic cells pairs are magnetically trapped at each array site. This method of producing large numbers of isolated heterotypic cell pairs is potentially useful in studies of cell-cell interactions between different cell types. [Preview Abstract] |
Monday, March 5, 2007 1:03PM - 1:15PM |
B38.00008: Detection of cancer protein using Spectroscopic Ellipsometry as Surface Plasmon Resonance Mode Yunbog Kim, Dongryul Jeon, Min-ah Woo, Myunghaing Cho Since the first application of surface plasmon resonance (SPR) for biosensing almost two decades ago, SPR has made great strides in terms of both the instrumentation and the application. We used spectroscopic ellipsometry as an SPR sensor to detect the reaction of HER2 protein of SKBR3 cancer cells with its antibody. Since the Psi value of ellipsometry is related to the reflectivity of P wave, the surface plasmon signal can be measured using spectroscopic ellipsometry. A glass plate coated with 50 nm-thick gold film was dipped in HER2 antibody solution for 1 hour. The substrate was then dipped in a soup containing broken SKBR3 cells to induce HER2 antibody-antigen reaction. The pure gold film exhibited a SPR peak at 2.04 eV. After the adsorption of HER2 antibody, the peak shifted to 1.99eV. After dipping in the soup of SKBR3 cells, the peak shifted to 1.96 eV. We believe this shift is due to the change in surface plasmon caused by binding of HER2 protein and antibody. The AFM images of the samples supported our conclusion. Our result adds an example to the possibility of using spectroscopic ellipsometry as an SPR mode for detecting cancer cells. [Preview Abstract] |
Monday, March 5, 2007 1:15PM - 1:27PM |
B38.00009: ABSTRACT WITHDRAWN |
Monday, March 5, 2007 1:27PM - 1:39PM |
B38.00010: In-line Phase Contrast Imaging of Soft Tissue in the Mammalian Cochlea Lixin Fan, C. Rau, I. Robinson, C.-P. Richter Soft tissue has been visualized in a mammalian cochlea with hard X-rays in-line phase contrast imaging at the UNICAT beamline 34 ID-C, APS. The sensation of hearing results from a series of complex events that transform acoustic pressure waves into the perception of sound. During the normal hearing process, sound energy is converted to mechanical energy by the middle ear, which then is converted to motions in the structures of the cochlea. To date, many aspects of the sound induced vibrations are still unclear. Firstly, mechanics of the cochlea are likely to changes by the manipulations, and secondly, cochlear micromechanics are unexplored for the cochlear middle section. Therefore, our objective is to measure the motion patterns of cochlear tissues in a closed cochlea. Thick mammalian cochlear slices have been imaged and were compared with those obtained by light microscopy. Furthermore, intact cochleae have been imaged to identify the soft tissue structures involved in the hearing process. [Preview Abstract] |
Monday, March 5, 2007 1:39PM - 1:51PM |
B38.00011: Dental Photothermal Radiometry: Theoretical Analysis. Anna Matvienko, Raymond Jeon, Andreas Mandelis, Stephen Abrams Dental enamel demineralization in its early stages is very difficult to detect with conventional x-rays or visual examination. High-resolution techniques, such as scanning electron microscopy, usually require destruction of the tooth. Photothermal Radiomety (PTR) was recently applied as a safe, non-destructive, and highly sensitive tool for the detection of early dental demineralization, artificially created on the enamel surface. The experiments showed very high sensitivity of the measured signal to incipient changes in the surface structure, emphasizing the clinical capabilities of the method. In order to analyze the biothermophotonic phenomena in a tooth sample during the photothermal excitation, a theoretical model featuring coupled diffuse-photon-density-wave and thermal-wave fields was developed. Numerical simulations identified the effects on the PTR signal of changes in optical and thermal properties of enamel and dentin as a result of demineralization. The model predictions and experimental results will be compared and discussed. [Preview Abstract] |
Monday, March 5, 2007 1:51PM - 2:03PM |
B38.00012: ABSTRACT HAS BEEN MOVED TO J21.00010 |
Monday, March 5, 2007 2:03PM - 2:15PM |
B38.00013: ABSTRACT HAS BEEN MOVED TO J21.00009 |
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