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

Basic principles of optical tweezers Experimental set-up Advantages of Raman Tweezer set-up Test measurements on micro particles and living cells Outline

Basic Principles of Optical Tweezers Light besides energy carries Lineer momentum Force Classical : EM theory, Radiation pressure Quantum : Photon momentum, Angular momentum Torque

Radiation Presure → Optical Trapping 1 mW 1μm F ~10 pN m ~pg F ~ 10 pN a ~10 5 g

(A. Ashkin, Biophys. J. (61), 1992) Single Ray Solution P : Power Momentum per unit time:

Extended Laser Beam

Large NA objectives Overfilling n 2 > n 1 Power ~1mW is enough to trap Critical Points for Optical Trapping

Experimental setup

1µm trapped polystyrene particle

4.6 µm trapped polystyrene particle

~ 5 µm trapped yeast cell

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. Advantages of Raman Tweezer Set-up

Excitation wavelength: 780 nm Power: 6 mW on the sample Accumulation: 100 s Raman spectrum of trapped polystyrene particle

Raman spectrum of trapped yeast cell C. Xie et al. Opt. Exp. 25,

Collaboration Istanbul University Physics Department Prof.Dr. Sevim Akyuz Optimizing Laser Tweezer Raman Spectrometer Investigation of interaction between cell membranes and their environment Future Work Support by the Scientific and Technological Research Council of Turkey under the project number 105T482 is gratefully acknowledged. Our Laser Spectroscopy Group at Istanbul Technical University Physics Engineering Department PhD student Seda Kin MsC student Uğur Parlatan BsC students Onur Pusuluk Berkin Malkoç Group leader Assoc.Prof. Dr. Gunay Basar

Thank You!