Chiroptical effects in the second harmonic signal of collagens I and IV.
We performed polarization-resolved surface second harmonic generation (SHG) experiments on thin films of collagen I and IV molecules, as well as conventional CD measurements. We found that collagen IV presents little CD and no SHG optical activity, whereas collagen I exhibits large chiroptical effects involving both one-electron and excitonic coupling mechanisms. We estimated that these chiral components enhance the SHG signal from fibrillar collagen in biological tissues by typically a factor of 2. By comparing the distinct behaviors of collagens I and IV in SHG microscopy and in surface SHG experiments, we concluded that SHG microscopy is a sensitive probe of the micrometer-scale structural organization of collagen in biological tissues.
Pena
Ana-Maria
AM
Laboratory for Optics and Biosciences, CNRS/INSERM, Ecole polytechnique, 91128 Palaiseau, France.
Boulesteix
Thierry
T
Dartigalongue
Thibault
T
Schanne-Klein
Marie-Claire
MC
D002942:Circular Dichroism; D024042:Collagen Type I / Q000737:chemistry*; D024141:Collagen Type IV / Q000737:chemistry*; D006801:Humans; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D012867:Skin / Q000737:chemistry; D013050:Spectrometry, Fluorescence
D024042:Collagen Type I; D024141:Collagen Type IV