This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.106.084616v1 91/4/1424    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Xiao, Y. Articles by Hutson, M. S. Search for Related Content PubMed PubMed Citation Articles by Xiao, Y. Articles by Hutson, M. S.

Wavelength-Dependent Collagen Fragmentation during Mid-IR Laser Ablation

Yaowu Xiao ^*, Mingsheng Guo , Kevin Parker  and M. Shane Hutson ^*

^* Department of Physics & Astronomy and Vanderbilt Institute for Integrative Biosystem Research & Education, Vanderbilt University, Nashville, Tennessee; Department of Physics, Fisk University, Nashville, Tennessee; and Department of Physics, Duke University, Durham, North Carolina

Correspondence: Address reprint requests to M. Shane Hutson, VU Station B #351807, Nashville, TN 37235. Tel.: 615-343-9980; Fax: 615-343-7263; E-mail: shane.hutson{at}vanderbilt.edu.

Mid-infrared free-electron lasers have proven adept in surgical applications. When tuned to wavelengths between 6 and 7 µm, such lasers remove defined volumes of soft tissue with very little collateral damage. Previous attempts to explain the wavelength-dependence of collateral damage have invoked a wavelength-dependent loss of protein structural integrity. However, the molecular nature of this structural failure has been heretofore ill-defined. In this report, we evaluate several candidates for the relevant transition by analyzing the nonvolatile debris ejected during ablation. Porcine corneas were ablated with a free-electron laser tuned to 2.77 or 6.45 µm—wavelengths with matched absorption coefficients for hydrated corneas that respectively target either tissue water or protein. The debris ejected during these ablations was characterized via gel electrophoresis, as well as Fourier transform infrared spectroscopy, micro-Raman and ¹³C-NMR spectroscopy. We find that high-fluence (240 J/cm²) ablation at 6.45 µm, but not at 2.77 µm, leads to protein fragmentation accompanied by the accumulation of nitrile and alkyne species. The candidate transition most consistent with these observations is scission of the collagen protein backbone at N-alkylamide bonds. Identifying this transition is a key step toward understanding the observed wavelength-dependence of collateral damage in mid-infrared laser ablation.

This article has been cited by other articles:

				A. Zavalin, D. L. Hachey, M. Sundaramoorthy, S. Banerjee, S. Morgan, L. Feldman, N. Tolk, and D. W. Piston Kinetics of a Collagen-Like Polypeptide Fragmentation after Mid-IR Free-Electron Laser Ablation Biophys. J., August 1, 2008; 95(3): 1371 - 1381. [Abstract] [Full Text] [PDF]

				Y. Xiao, M. Guo, P. Zhang, G. Shanmugam, P. L. Polavarapu, and M. S. Hutson Wavelength-Dependent Conformational Changes in Collagen after Mid-Infrared Laser Ablation of Cornea Biophys. J., February 15, 2008; 94(4): 1359 - 1366. [Abstract] [Full Text] [PDF]