Ultrafast infrared chemical imaging of live cells

Mid-infrared (mid-IR) spectroscopy provides a unique chemical fingerprint of biomaterials, including DNA and proteins, from single molecules to highly organised structures and, ultimately, to live cells and tissues. However, acquiring good signal-to-noise mid-IR spectroscopic images, at the cellular level, typically involves a synchrotron, with imaging times of order of minutes. Here we use a new laser-based table-top IR spectroscopic micro-imaging system, to obtain vibrational fingerprint signatures of living human ovarian cancer cells at a diffraction limited spatial resolution, and at a spectral resolution (< 20 cm(-1)) sufficient to map out the spatial distributions of chemical moieties inside the cell itself. The bright laser pulses give very high signal-to-noise images, and similar to 100 psec image acquisition times that are roughly 10(11) times faster than current mid-IR spectroscopic imaging techniques. The imaging method is quantitative, non-phototoxic, marker-free and easily fast enough to freeze moving, living specimens. It can be applied to a range of cell-level biochemical processes, and we believe it could impact on the fields of drug action, cell physiology, pathology and disease as a whole.