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Séminaire de Silvia Santucci

Optical sample manipulations for synchrotron radiation probing of biological and soft matter objects in aqueous environments


Silvia Santucci - European Synchrotron Radiation Facility (ESRF) Grenoble

 

Optical tweezers (OT)1, based on the trapping capabilities of focused laser beams, have found numerous applications in different fields from physics to life sciences2. OT allow to trap, manipulate, sort and dispose in arrays single particles of tens of microns to tens of nanometers in diameter. In the 10 pico- to 10 nano-Newton range, optical forces are a suitable contact-free manipulation tool for fragile objects. This includes single cells, sub-cellular macromolecules, colloidal systems, microbubbles and nanoparticles .2,3 OT can be used in combination with several techniques, e. g., fluorescence microscopy, video tracking, Raman spectroscopy, dynamic light scattering, microrheology and in applications like laser cutting and self assembly.

Recently, we have introduced the use of optical sample manipulations for synchrotron radiation (SR) in situ investigations.4 Indeed, the availability of intense microbeams and, more recently, nanobeams at 3rd generation SR sources allows the probing of local structures in hierarchically organized materials by small-angle and wide angle X-ray scattering techniques (SAXS/WAXS).5

 

We have realized and commissioned an optical tweezers setup adapted to SR environment requirements. In this talk, I will report on our recent achievements. Objects from a few microns up to 40 microns in size can be trapped and manipulated for extended periods of time. The performance of the setup in the beamline environment has been tested by WAXS and SAXS scattering experiments on single optically trapped starch granules, using a synchrotron radiation microfocussed beam. We have then provided the first evidence for the feasibility of microdiffraction on optically trapped protein crystals (35 µm in diameter).
The effect of radiation damage at room temperature has been investigated by repeated raster-scaning up to the complete loss of the structural order. In the near future the combination of optical forces, synchrotron and laboratory probes may initiate the development of new research fields for fragile, biological and soft matter objects.

 

(1) A. Ashkin, Phys. Rev. Lett. 24, 156 (1970) ; A. Ashkin, J. M. Dziedzic, Appl. Phys. Lett., 19, 283 (1971) ; A. Ashkin, J. M. Dziedzic, J. E. Bjorkholm, S. Chu, Optics Letters 11, 288 (1986).

(2) A. Ashkin, Optical trapping and manipulation of neutral particles using lasers ; World Scientific Publishing Co. Pte. Ltd., 2006.

(3) D. J. Stevenson, F. Gunn-Moore, K. Dholakia, J. Biom. Optics 15, 041503 (2010) ; J. R. Moffitt, Y. R. Chemla, S. B. Smith, C. Bustamante, Ann. Rev. of Biochem. 77, 205 (2008).

(4) Optical tweezers for touchless sample manipulation in synchrotron radiation experiments : S. C. Santucci, H., Amenitsch, D. Cojoc and C. Riekel, chapter of the book “Synchrotron radiation and Structural proteomics" Volume III of series of books on Nanobiotechnology by Pan Stanford publishing (series editor C. Nicolini) ; in press, 2011.

(5) C. Riekel, Rep. on Prog. in Phys. 63, 233 (2000) ; O. Paris, Biointerphases 3, FB16–FB26 (2008) ; C. Riekel, M. Burghammer, R. J. Davies, R. Gebhardt, and D. Popov, Fundaments of soft condensed matter scattering and diffraction with microfocus techniques. In : Applications of Synchrotron Light to Non-Crystalline Diffraction in Materials and Life Sciences. (Series Lecture Notes in Physics) (Eds García- Gutiérrez, M. C., Nogales, A., Gómez, M. and Ezquerra, T. A.). (Springer-Verlag, Heidelberg). Vol. 776 (2009).