IR spectroscopy has long been used to study secondary structures of dissolved proteins in neat buffer<i>. </i>The application of IR spectroscopy to provide information on protein structure in exhumed tissues is a more recent application of the technique. In addition to improved signal-to-noise for global protein structural measurements, 2D IR spectroscopy expands the linear spectroscopy imaging toolbox by providing information on vibrational couplings, transition dipole strengths, and exciton delocalization. Using metrics such as cross-peak locations, transition dipole measurements, and anharmonic shifts in addition to fundamental peak frequency, 2D IR has recently been used to study amyloid β-sheets in porcine and human cataract lens tissue. In this study, 2D IR spectroscopy is used to study exhumed mouse pancreas tissues, and we present each metric available from the 2D IR spectrum in the form of hyperspectral images. We suggest 2D IR bioimaging as a complement to other established methods of imaging such as antibody staining, fluorescent staining, and electron microscopy. Additional challenges to data interpretation, such as the effects of chemical preservation agents on protein structure and time-dependent tissue degradation will also be discussed.

Formalin fixation does not arrest protein structural degradation as observed with 2D IR bioimaging

ACS Fall 2021

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