[Cnqo] Fwd: [Physstaff] Colloquium: Paola Borri (Cardiff) Coheren Multi-Photon Microscopy 3pm Wed 19/3/2014

[Francesco Papoff]

Dear All,

Prof Paola Borri will be around most of Wednesday, please let me know if 
you wish to talk to her.

Best regards

Francesco

________________________________________________________________________________________________________________

We are happy to have Prof Paola Borri (Cardiff) give this week's 
colloquium. As usual, there will be tea/coffee afterwards.

Title: Shedding new light on cells with coherent multiphoton microscopy

Time/Date: 3pm Wednesday 19^th March 2014

Room: JA8.07

Abstract:

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.

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.

References

[1] Andreas Zumbusch, Wolfgang Langbein, Paola Borri "Nonlinear 
vibrational microscopy applied to lipid biology" Progress in Lipid 
Research 52, 615 (2013).

[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).

[3] Wolfgang Langbein et al "Single source coherent anti-Stokes Raman 
micro-spectroscopy using spectral focusing", Applied Physics Letters 95, 
081109 (2009).

[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).

[5] Francesco Masia et al "Quantitative chemical imaging and 
unsupervised analysis using hyperspectral coherent anti-Stokes Raman 
scattering microscopy" Anal. Chem. 85, 10820 (2013).

[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).

http://www.strath.ac.uk/physics/research/colloquia/

--------

Dr Daniel K. L. Oi

Lecturer in Quantum Information

Computational Non-Linear & Quantum Optics

SUPA Department of Physics

University of Strathclyde

Glasgow G4 0NG, UK

Tel: +44 141 548 3112

Fax: +44 141 552 2891

The University of Strathclyde is a charitable body, registered in 
Scotland, number SCO15263



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