Combined laser micro-manipulation and small-angle X-ray scattering

Transcription

1 Combined laser micro-manipulation and small-angle X-ray scattering Enrico Ferrari TASC National Laboratory: Advanced Technologies and nanoscience (CNR-INFM, National Institute for the Physics of Matter) Trieste, Italy

2 Outline Introduction to Optical Tweezers (OT) Overview of the manipulation capabilities and applications Combined SAXS/OT at ID13 Future developments 2/16

3 Introduction: OT working principle Johannes Kepler: tails of comets always point away from the sun (radiation pressure) Isaac Newton: for every action there exists an equal but opposite reaction Pin Linear momentum for a ray of light refracted by a transparent micro-sphere dp F= dt Pout p = h/λ Photon momentum P 3/16

4 Introduction: OT working principle confinement along the optical axis is obtained by focusing a laser beam through an objective A single-beam 3D trap is obtained by tightly focusing a laser beam through a high NA objective Arthur Ashkin et al., Arthur Ashkin et al., PRL 24, 156 (1970) Optics Letters 11, 288 (1986) 4/16

5 Introduction: OT setup and main characteristics nmw F= Q c F = trapping force Q = dimensionless efficiency coefficient W = laser power nm = refractive index of the medium C = speed of light Typical particles size: 5 nm 20 µm Typical stiffness: 100 pn/µm Typical displacements: nm Typical forces: pn 5/16

6 Manipulation: multiple trapping by means of DOEs 2D or 3D arrays of traps can be generated by projecting computer generated Diffractive Optical Elements (DOEs) to a Spatial Light Modulator (SLM) SLM DOE Input Wave (Gaussian) E. Ferrari et al. Microelectronic Engineering 78-79, 125 (2005) 6/16

7 Manipulation: cells (indirect- direct) Indirect cells manipulation: micro-beads are used to mimic the mechanical environment of cells in a tissue (in collaboration with Institute Jacques Monod in Paris) V. Emiliani et al. Optics Express, (2005) Direct cells manipulation: cells arraying and sorting (tissue engineering) E. Di Fabrizio et al, Microscopy Research and Technique 65, 252 (2004) 7/16

8 Manipulation: low index particles Trapping and manipulation of ultrasound contrast agents (UCA) The DOE converts a Gaussian beam to a Laguerre-Gaussian bubble oscillations excited by a 2.25 MHz ultrasound burst recorded at 15 MHz In collaboration with Bracco Research (Geneva) and Physics of Fluids Dept, Univ. of Twente, NL V. Garbin et al. APL (2007), accepted 8/16

9 Combined SAXS/OT Phospholipid Membrane Stack Liposome (MLV) Lyotropic Phases H2O dw d Bilayer Micelle db 1-10 µm Phospholipid O O O P O O + O O CH3 Hexagonal Phase O C C H H CH3 Cubic Phase N H3C CH CH3 3 Hydro philic Hydro phobic 9/16

10 Combined SAXS/OT DETECTOR X-RAY BEAM Capillary: Glass, Ø 100 µm Laser: CW Yb doped fiber laser, 1064 nm, P = 100mW-10W, linear polarized (IPG Photonics) CAPILLARY OBJECTIVE DOE: implemented on an SLM (Hamamatsu), calculated with spherical wave approach D. Cojoc et al, Proceedings of SPIE 6326, 63261M (2006) DM LASER SLM CMOS 10/16

11 Combined SAXS/OT 1. Objective (60X) 2. Objective (40X) 3. Capillary 4. Sample holder ESRF ID 13 KB, Ref. Lenses Beam size: 1 µm E = 13.0 kev (λ = Å) 11/16

12 Combined SAXS/OT Diffraction from single clusters Integrated diffraction pattern Diffraction image: exposure time 5 s POPE (1 wt%) in 1 mol CaCl2, Cluster size: 10 µm, Liposome size: 1-2 µm, Phase: Liquid crystalline Lα 12/16

13 Combined SAXS/OT Diffraction from single clusters Capillary wall ΔY: 75 µm Capillary wall 10 µm ΔZ: 85 µm Plot of the integrated Intensity during scanning Step width: 2.5 x 5 µm Imaging of the cluster in the capillary POPE (1 wt%) in 1 mol CaCl2, Cluster size: 10 µm, Liposome size: 1-2 µm, Phase: Liquid crystalline Lα 13/16

14 Combined SAXS/OT Diffraction from multiple clusters ΔY: 48 µm Capillary wall A Capillary Wall Liposom Clusters 20µm µm 20 B A B CapillaryWall ΔZ: 56 µm Plot of the integrated intensity Step width: 10 x 8 µm Imaging of the clusters in the capillary POPE (1 wt%) in 1 mol CaCl2, Cluster size: 10 µm, Liposome size: 1-2 µm, Phase: Liquid crystalline Lα 14/16

15 Conclusions and outlook Capillary replaced by a microfluidic device Trapping and imaging with the same objective Multiple traps for vescicles fusion 15/16

16 Acknowledgements Christian Riekel, Manfred Burghammer (ID13) Heinz Amenitsch, Michael Rappolt, Barbara Sartori (Graz/Elettra) Dan Cojoc, Enzo Di Fabrizio, Valeria Garbin (TASC) 16/16