Book of Abstracts - Ruhr-Universität Bochum

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ISBOMC `10 5.7 – 9.7. 2010 Ruhr-Universität Bochum
Subcellular Imaging of a Re(CO)3 Complex by Photothermal Infrared
Spectromicroscopy (PTIR).
Anne Vessières, a Clotilde Policar, b Marie-Aude Plamont, a Sylvain Clède, b Alexandre Dazzi c
a ENSCP, CNRS-UMR 7223, 11 rue P. et M. Curie, F-75231 Paris Cedex 05, France, b Département
Chimie de l’ENS, CNRS-UMR 7203, 24 rue Lhomond, F-75231 Paris Cedex 05, c Laboratoire de
Chimie Physique, CNRS-UMR 8000, Université Paris-Sud 11, F-91405 Orsay Cedex,
E-mail: a-vessieres@chimie-paristech.fr
The most widely developed techniques for bio-imaging are those based on fluorescence
spectroscopy, however vibrational techniques including infra-red (IR) are also valuable. However, in
classical optical microscopy, sub-micrometric resolutions are not attainable in the mid-IR-range, as the
diffraction criterion imposes resolution higher than �/2 (i.e. 2.5 µM at 2000 cm -1 ) which is not well
suited for intracellular mapping. To reach sub-micrometric resolution, near-field techniques are
mandatory. Photothermal induced resonance (PTIR) is a cutting edge technique using a set-up recently
patented by Dazzi et al., 1 coupling atomic force microscopy (AFM) and a tunable infrared laser to
make spatially resolved absorption measurements in the IR-range. It has been successfully used to
map a single air-dried E. coli cell by irradiation in the amide I and II bands. 2 The next challenge is the
identification and localization of exogeneous diluted compounds inside single cells. The Re(CO)3 unit
grafted to a hydroxy-tamoxifen-like molecule has been selected for this study as it is stable in
biological environments and displays intense absorption in the 1850 – 2100 cm -1 region where
biological samples are transparent.
Figure : left: AFM-set up. middle: PTIR mapping at 1925 cm -1 of a single cell incubated 1h with 10
µM of the Re(CO)3 complex (red = high concentration) right : spectromicroscopy at the nucleus
We will present the results of the chemical imaging of this Re complex, inside a single cell,
using PTIR. Cells are initially located on the surface of a ZnSe prism by using the AFM topology.
Then the complex is localized thanks to its two characteristic �CO bands at 1925 and 2017 cm -1 . Cells
showed an uneven distribution of the complex with one hot spot (red area on the picture above) and
cold regions (blue zones). Interestingly, this location seems to correspond to cell nucleus located using
irradiation at 1240 cm -1 (phosphate band) and 1650 cm -1 (amide I of proteins). In addition, a spectrum
recorded inside the hot spot shows the two characteristic bands of the complex at 1925 and 2017 cm -1 ,
thus confirming its presence (right part of the figure).
References
1. A. Dazzi, M. Reading, P. Rui, K. Kjoller, Patent 2008, WO/2008/143817 A. B. Lastname, C. D.
2. A. Dazzi, R. Prazeres, F. Glotin, J.-M. Ortega, Infrared Physics Techn. 2006, 49, 113.
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