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İstanbul Teknik Üniversitesi
CONSTRUCTION OF A RAMAN TWEEZER SYSTEM FOR INVESTIGATION OF BIOLOGICAL MOLECULES Günay Başar İstanbul Teknik Üniversitesi International Symposium on Molecular Spectroscopy 62nd Meeting - June 18-22, 2007
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Outline Basic principles of optical tweezers Experimental set-up
Advantages of Raman Tweezer set-up Test measurements on micro particles and living cells
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Basic Principles of Optical Tweezers
Light besides energy carries Lineer momentum Force Classical : EM theory, Radiation pressure Quantum : Photon momentum, Angular momentum Torque
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F ~ 10 pN a ~105 g Radiation Presure→ Optical Trapping 1 mW 1μm
m ~pg F ~ 10 pN a ~105 g
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Single Ray Solution P : Power Momentum per unit time:
(A. Ashkin, Biophys. J. (61), 1992)
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Extended Laser Beam
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Critical Points for Optical Trapping
Large NA objectives Overfilling n2 > n1 Power ~1mW is enough to trap
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Experimental setup
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1µm trapped polystyrene particle
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4.6 µm trapped polystyrene particle
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~ 5 µm trapped yeast cell Yeast cell transportation on X-Y plane
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~ 5 µm trapped yeast cell
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Advantages of Raman Tweezer Set-up
The ability to get Raman Spectrum of a single living object in their natural environment. Decreasing of background signals from cover slip. No mechanical immobilization of living cells.
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Raman spectrum of trapped polystyrene particle
Excitation wavelength: 780 nm Power: 6 mW on the sample Accumulation: 100 s
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Raman spectrum of trapped yeast cell
C. Xie et al. Opt. Exp. 25,
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Future Work Our Laser Spectroscopy Group
Optimizing Laser Tweezer Raman Spectrometer Investigation of interaction between cell membranes and their environment Our Laser Spectroscopy Group at Istanbul Technical University Physics Engineering Department Collaboration Istanbul University Physics Department Prof.Dr. Sevim Akyuz Group leader Assoc.Prof. Dr. Gunay Basar PhD student Seda Kin MsC student Uğur Parlatan BsC students Onur Pusuluk Berkin Malkoç Support by the Scientific and Technological Research Council of Turkey under the project number 105T482 is gratefully acknowledged.
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Thank You!
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