Combining field effect scanning electron microscopy, deep UV fluorescence, Raman, classical and synchrotron radiation Fourier transform Infra-Red Spectroscopy in the study of crystal-containing kidney biopsies

Crystal formation in kidney tissue is increasingly recognized as a major cause of severe or acute renal failure. Kidney biopsies are currently performed and analyzed using different staining procedures. Unfortunately, none of these techniques are able to distinguish the different Ca phosphates (e.g., amorphous or nanostructured Ca phosphate apatite, octacalcium phosphate, brushite…) or Ca oxalates (whewellite and weddellite). Moreover, the crystal’s morphology, a structural parameter proven as a major information to the clinician regarding kidney stones, is not taken into account. Such major limitations call for a different research approach, based on physicochemical techniques. Here we propose classical observations through field-emission scanning electron microscopy experiments combined with energy dispersive spectroscopy as well as measurements through Raman and μFourier transform Infra-Red Spectroscopy. If necessary, in the case of microcrystals, observations using cutting edge technology such as Synchrotron Radiation (SR) – FTIR or SR-UV visible spectroscopy can be subsequently performed on the same sample. Taken together this set of diagnostic tools will help clinicians gather information regarding the nature and the spatial distribution at the subcellular scale of different chemical phases present in kidney biopsies as well as on the crystal morphology and therefore obtain more precise diagnosis.