Chemically resolved imaging of biological cells and thin films by infrared scanning near-field optical microscopy
The infrared (IR) absorption of a biological system can potentially report on fundamentally important microchemical properties. For example, molecular IR profiles are known to change during increases in metabolic flux, protein phosphorylation, or proteolytic cleavage. However, practical implementation of intracellular IR imaging has been problematic because the diffraction limit of conventional infrared microscopy results in low spatial resolution. We have overcome this limitation by using an IR spectroscopic version of scanning near-field optical microscopy (SNOM), in conjunction with a tunable free-electron laser source. The results presented here clearly reveal different chemical constituents in thin films and biological cells. The space distribution of specific chemical species was obtained by taking SNOM images at IR wavelengths ( l) corresponding to stretch absorption bands of common biochemical bonds, such as the amide bond. In our SNOM implementation, this chemical sensitivity is combined with a lateral resolution of 0.1 mum (approximate tolambda1/70), well below the diffraction limit of standard infrared microscopy. The potential applications of this approach touch virtually every aspect of the life sciences and medical research, as well as problems in materials science, chemistry, physics, and environmental research.
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Vanderbilt Univ, Dept Physiol & Mol Biophys, Nashville, TN 37232 USA. Ecole Polytech Fed Lausanne, Inst Phys Appl, Lausanne, Switzerland. Ist Stuttura Mat, Rome, Italy. USN, Res Lab, Opt Sci Div, Washington, DC 20375 USA. Vanderbilt Univ, Dept Phys & Astron, Nashville, TN 37235 USA. Univ Roma La Sapienza, Dept Phys, I-00185 Rome, Italy. Piston, DW, Vanderbilt Univ, Dept Physiol & Mol Biophys, 702 Light Hall, Nashville, TN 37232 USA.
ISI Document Delivery No.: 726AQ
Record created on 2006-10-03, modified on 2016-08-08