Chiroptical effects in the second harmonic generation from collagens I and IV

PHYS 559

A-M. Pena, ana-maria.pena@polytechnique.edu, T. Boulesteix, T. Dartigalongue, M. Strupler, M-C. Schanne-Klein, and F. Hache, francois.hache@polytechnique.edu. Laboratoire d'Optique et Biosciences CNRS-INSERM, Ecole Polytechnique, Route de Saclay, Palaiseau, 91128, France
We studied chiroptical effects in the second harmonic generation (SHG) from collagen. These effects are small for collagen IV molecules, in accordance with the numerous interruptions in the helical domains of this network forming collagen. Conversely, collagen I molecules exhibit large chiroptical effects involving both one-electron and excitonic coupling mechanisms, which result in a twofold enhancement of the SHG signal. However, except for these chiral components, signals from both types of collagen molecules present similar orders of magnitude. We therefore attributed the absence of SHG signal from collagen IV in biological tissues to the lack of any alignment within the collagen IV molecules, and the large collagen I SHG signals to coherent effects due to the high density and quasi-crystalline order in collagen fibrils. This study shows that SHG microscopy is a sensitive probe of the micrometer-scale structural organization of collagen in tissues.
 

General Posters
7:30 PM-10:00 PM, Wednesday, March 28, 2007 Hyatt Regency Chicago -- Riverside Center, Poster

Division of Physical Chemistry

The 233rd ACS National Meeting, Chicago, IL, March 25-29, 2007