Application of Synchrotron FTIR Imaging for Cells

Thanks to the ultra-high brightness and high spatial resolution of synchrotron infrared light source, synchrotron radiation based Fourier-transform infrared (SR-FTIR) microspectroscopy is widely used in multidisciplinary field. Especially in the biomedical field, SR-FTIR has been widely employed in the structural and functional characterization of unstained and unlabeled biomolecules as a non-destructive technique. In the recent ten years, with the development of SR-FTIR microspectroscopic technique, biochemists and spectral scientists have expanded their interests from the tissue level FTIR imaging (tissue FTIR imaging, which normally focus on imaging a tissue section) to single cell level FTIR imaging (cell FTIR imaging, which focus on imaging of a single functional or live cell). However, there are several problems need to be overcome in cell FTIR imaging. For example, (1) water in cell and/or in medium has strong absorption in amide I band; (2) uneven surface of cell leads to Mie scattering of FTIR spectra; (3) complexity and uncertainty of FTIR spectra of cell affect the validity and accuracy of the data analysis. On the other hand, biochemists and spectral scientists have designed fruitful strategies to solve these problems. Therefore, we summarized the studies about cell SR-FTIR imaging in the past ten years in this review. We firstly describe the sample preparation, experimental design and data analysis methods in these published works, and then put forward the problems and the corresponding solutions on cell SR-FTIR imaging. We believe with the development of multibeam synchrotron source/focal plane array (FPA) system, SR-FTIR imaging will become a very promising tool to detect structures and functions not only for cells, but also for many other materials in different fields