Correlative Spectromicroscopy and Tomography for Biomedical Applications Involving Electron, Ion, and Soft X-ray Microscopies

Abstract

Abstract

Nano-imaging trace elements at organelle levels in substantia nigra overexpressing α-synuclein to model Parkinson’s disease

“…XRF of K-lines using hard X-rays has high trace sensitivity and is the only method to detect few ppb 58 . It complements the scope of compositional analyses of organic structures and speciation of minor metal contents linked to them, reachable by soft X-ray correlative microscopy, with a comparable 20-30 nm resolution in 100-200 nm thin tissue sections of brains 26 . Hence, different types of compartments, organelles, or subsets of granules were imaged from which pathological perturbations were discriminated in several neurons.…”

“…The relative count rate of a compartment “ i ” with respect to the nuclear compartment “ n ” and its uncertainty are defined as: where S , σ S , and N designate the number of counts, their uncertainties, and the number of pixels, respectively, in the compartments. S and σ S are the output of the PyMca fitting procedure 26 . As a measure of the fluorescence count rate reproducibility, the uncertainty of each pixel, subject to Poisson statistics, is the square root of the number of counts.…”

“…Developing direct imaging of metals at the subcellular level, in particular that of organelles in the neurons which are vulnerable to disease, would be a major step toward understanding the pathogenic mechanisms involved 23 . Among the analytical approaches developed to investigate physiological heterogeneities of trace elements in brains 24 , 25 , synchrotron radiation-induced X-ray fluorescence (XRF hereafter) is part of the few imaging approaches 26 , 27 , the only non-destructive multi-elemental method of high sensitivity. XRF has been used to analyze Fe traces in brains affected by Parkinson’s disease 28 , showing that this element is heterogeneously distributed in brain tissues and accumulates in both the neuronal cells and the extra-neuronal substantia nigra tissue of Parkinson’s patients.…”