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Dear All, <br>
<br>
Prof Paola Borri will be around most of Wednesday, please let me
know if you wish to talk to her.<br>
<br>
Best regards<br>
<br>
Francesco<br>
<br>
________________________________________________________________________________________________________________<br>
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<p class="MsoNormal">We are happy to have Prof Paola Borri
(Cardiff) give this week’s colloquium. As usual, there will be
tea/coffee afterwards.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Title: Shedding new light on cells with
coherent multiphoton microscopy<o:p></o:p></p>
<p class="MsoNormal">Time/Date: 3pm Wednesday 19<sup>th</sup>
March 2014<o:p></o:p></p>
<p class="MsoNormal">Room: JA8.07<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Abstract:<o:p></o:p></p>
<p class="MsoNormal">Optical microscopy is an indispensable tool
that is driving progress in cell biology, and is still the
only practical means of obtaining spatial and temporal
resolution within living cells and tissues. Much effort is
being devoted recently to achieve intrinsic three-dimensional
(3D) spatial resolution by exploiting optical nonlinear
effects which can only take place in the small focal volume
where high photon densities are reached. One of the most
utilised multiphoton (ie nonlinear) microscopy techniques is
two-photon fluorescence where the biomolecules of interest are
labelled with fluorophores which are optically excited via
simultaneous absorption of two photons. However, these
modified biomolecules raise questions if their behaviour is
real or artefactual. Furthermore, all organic fluorophores are
prone to photo-bleaching which severely limits time-course
observations and is accompanied by toxicity effects and
consequent cell damage.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Coherent Antistokes Raman Scattering (CARS)
microscopy has recently emerged as a new multiphoton
microscopy technique which overcomes the need of fluorescent
labelling and yet retains biomolecular specificity and
intrinsic 3D resolution [1]. We have developed in our
laboratory two home-built CARS microscopes featuring
innovative CARS excitation/detection schemes. In particular,
we have demonstrated dual frequency differential-CARS (DCARS)
with strongly suppressed non-resonant background and improved
chemical sensitivity [2] and single-laser CARS [3] utilising
femtosecond laser pulses linearly chirped by glass dispersion.
Our second generation single-broadband-laser D-CARS microscope
features a single 5fs Ti:Sa source with 350nm bandwidth
capable of exciting a wide vibrational range from 1000cm-1 to
3500cm-1 [4] thus enabling powerful hyperspectral microscopy
analysis [5]. Furthermore we have invented and demonstrated a
novel imaging modality, based on the resonant Four-Wave Mixing
(FWM) of colloidal nanoparticles. Results on this work showed
that gold nanoparticles can be used as alternative labels
beyond fluorescence by exploiting their resonant FWM, to
achieve a novel coherent multiphoton microscopy modality free
from background and with a spatial resolution significantly
surpassing the one-photon diffraction limit [6]. I will
present our latest progress with both techniques and their
applications to cell imaging.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">References<o:p></o:p></p>
<p class="MsoNormal">[1] Andreas Zumbusch, Wolfgang Langbein,
Paola Borri “Nonlinear vibrational microscopy applied to lipid
biology” Progress in Lipid Research 52, 615 (2013).<o:p></o:p></p>
<p class="MsoNormal">[2] Israel Rocha-Mendoza et al
“Differential Coherent Antistokes Raman scattering Microscopy
using linearly-chirped ultrafast laser pulses”, Optics Letters
34, 2258 (2009), ibid “Quadruplex CARS micro-spectroscopy”, J.
Raman Spectrosc. 44, 255 (2013).<o:p></o:p></p>
<p class="MsoNormal">[3] Wolfgang Langbein et al “Single source
coherent anti-Stokes Raman micro-spectroscopy using spectral
focusing”, Applied Physics Letters 95, 081109 (2009).<o:p></o:p></p>
<p class="MsoNormal">[4] Claudia Di Napoli et al
“Chemically-specific dual/differential CARS micro-spectroscopy
of saturated and unsaturated lipid droplets”, Journal of
Biophotonics 7, 68 (2014); I. Pope et al “Simultaneous
hyperspectral differential-CARS, TPF and SHG microscopy with a
single 5 fs Ti:Sa laser” Optics Express 21, 7096 (2013).<o:p></o:p></p>
<p class="MsoNormal">[5] Francesco Masia et al “Quantitative
chemical imaging and unsupervised analysis using hyperspectral
coherent anti-Stokes Raman scattering microscopy” Anal. Chem.
85, 10820 (2013).<o:p></o:p></p>
<p class="MsoNormal">[6] Francesco Masia et al “Resonant
four-wave mixing of gold nanoparticles for three-dimensional
cell microscopy”, Optics Letters 34, 1816 (2009). ibid
“Measurement of the dynamics of plasmons inside individual
gold nanoparticles using a femtosecond phase-resolved
microscope” Phys. Rev B 85 235403 (2012).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a moz-do-not-send="true"
href="http://www.strath.ac.uk/physics/research/colloquia/">http://www.strath.ac.uk/physics/research/colloquia/</a><o:p></o:p></p>
<p class="MsoNormal">--------<o:p></o:p></p>
<p class="MsoNormal">Dr Daniel K. L. Oi<o:p></o:p></p>
<p class="MsoNormal">Lecturer in Quantum Information<o:p></o:p></p>
<p class="MsoNormal">Computational Non-Linear & Quantum
Optics<o:p></o:p></p>
<p class="MsoNormal">SUPA Department of Physics<o:p></o:p></p>
<p class="MsoNormal">University of Strathclyde<o:p></o:p></p>
<p class="MsoNormal">Glasgow G4 0NG, UK<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Tel: +44 141 548 3112<o:p></o:p></p>
<p class="MsoNormal">Fax: +44 141 552 2891<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The University of Strathclyde is a
charitable body, registered in Scotland, number SCO15263<o:p></o:p></p>
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