Biomedical Applications at IRSR Beamlines

Nevertheless, one may wonder about the significance of the spatial resolution parameter for single cell analysis. Indeed, the sub-cellular components of a eukaryotic cell have sizes comparable to or smaller than the spatial resolution achievable by FTIR microscopy. For example the nucleus is 1-3 pm, the mitochondria 1 pm, the ribosomes, lisosomes and vesicules 1 pm, etc. The size of the FTIR probe in the mid-IR is significantly larger than those for VUV, X-ray and NMR, which all work below a spatial resolution of 1 pm. However, with a spatial resolution of about 1 pm, FTIR microscopy provides molecular information on sub-cellular components of cells unavailable by other techniques. 

The analysis of tissues by IRSR microscopy achieves the highest performance in hard tissues such as bone, or chondrocytes, which benefit from the brilliance of SR by allowing transmission mode analyses of thin (4-6 pm) and un-decalcified tissue sections. Comparable results could be obtained using a conventional laboratory system, but with tissue thicknesses between 2 and 4 pm. Thus, SR allows analysis of bone tissue sections 50% thicker than Globar sources in transmission mode. 

Infrared signal measured through various aperture sizes using a synchrotron source versus a Globar source. Data collected with a confocal IR microscope and a single-point detector. (Reprinted from ref. 72.) 

However, an exhaustive comparison is still lacking, and in general a limited number of SR-based FTIR microscopy studies are available on hard tissues. 

IRSR sources provide a brilliance at least two orders of magnitude higher than a conventional source, resulting in a higher photon flux at small apertures, i.e. below 10 pm x 10 The advantage of an SR source for IR microscopy 

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