Simultaneous Detection of Organics Leading to Spatial and Temporal Multidimensional Chemical Imaging (MDCI)

The holy grail of chemical imaging is to provide spatially and temporally resolved information about heterogeneous samples on relevant scales. Synchrotron-based Fourier Transform infrared imaging¹ combines rapid, non-destructive chemical detection with morphology at the micrometer scale, to provide value added results to standard analytical methods. A label free approach, it inherently evaluates a broad array of wide organic materials, with minimal sample preparation and modification. Examples presented here demonstrate the broad applicability of this approach to detect complex chemical information.

 Elucidating the molecular architecture of plant cell walls is one of the most challenging problems in plant biology. Wood is a composite material (30% lignin, 25% hemicellulose, and up to 50% cellulose) that is characterized by long fibrous cells with thick cell walls, formed by different layers, surrounding the void space of a lumen. Molecular assembly of lignocellulose and hemicellulose in cell walls provides the natural strength, toughness and utilitarian properties of wood². Chemical images of the lignin and cellulose distribution in wood cell walls and changes as a function of exposure to wood treatments will be presented.

 Spectrochemical analyses of hydrated, living single cells require high resolution (spatial and spectral) data, particularly when the goal is to monitor changes due to environmental stresses, in vivo on individual, algal cells, with subcellular resolution. Here, we identify carbon fixation in algal cells in real time by monitoring the concentrations of carbon containing macromolecules, and detecting time dependent changes. 

 Biomarkers generated from infrared signatures of in situ subcellular chemistry of diseased tissue hold the promise of illuminating pathological progression of disease. Examples from flash frozen tissue samples of mouse brain provide an example of biomolecular imaging in situ, with subcellular resolution.  Label free imaging and biochemical analysis for tissues from two transgenic mouse models of Alzheimer disease (TgCRND8 and 3xTg) that exhibit different features of pathogenesis³.  

¹ M.J. Nasse, et al. “High resolution Fourier-transform infrared chemical imaging with multiple synchrotron beams”, Nature Methods, 8, (2011) 413-416

² Ross , R. J. et al., "Wood Handbook: Wood as an Engineering Material", Forest Products Laboratory General Technical Report FPL-GTR-190. US FS, FPL, Madison, WI, p. 508 (2010).

³ M.Z. Kastyak-Ibrahim, et al. “Biochemical label-free tissue imaging with subcellular –resolution synchrotron FTIR with Focal Plane Array Detector,” NeuroImage 60, (2012) 376-383.