Vibrational spectroscopic imaging of pathogens, microorganisms, and their interactions with host systems

Vibrational spectroscopy has recently been increasing in popularity, especially when implemented as a label-free imaging mode. The use of light scattering in Raman imaging, or light absorption in infrared (IR) imaging, where the light wavelengths are selected to probe molecular bonds in the sample, allows a unique view of the molecular makeup of a sample. Generally non-invasive and highly sensitive to spatiotemporal changes in sample composition, vibrational spectroscopic imaging has very large potential in a wide range of fields. Here we review recent work in implementing both Raman and IR imaging, with particular attention to how the imaging itself, meaning the particular spatial distributions of spectra plays a role in generating novel findings. In general, for both Raman and IR imaging, technological developments are rapidly progressing, leading to higher imaging resolutions (especially for IR), images with higher signal-to-noise, substantially faster measurements, and more refined chemometric analysis by way of computational advances. In light of this, the current work highlights emerging applications that are now possible and indicates the potential for future applications of vibrational spectroscopic imaging for biological analysis.