A Review of ex vivo Elemental Mapping Methods to Directly Image Changes in the Homeostasis of Diffusible Ions (Na+, K+, Mg2 +, Ca2 +, Cl–) Within Brain Tissue

Abstract

Diffusible ions (Na + , K + , Mg 2+ , Ca 2+ , Cl −) are vital for healthy function of all cells, especially brain cells. Unfortunately, the diffusible nature of these ions renders them difficult to study with traditional microscopy in situ within ex vivo brain tissue sections. This mini-review examines the recent progress in the field, using direct elemental mapping techniques to study ion homeostasis during normal brain physiology and pathophysiology, through measurement of ion distribution and concentration in ex vivo brain tissue sections. The mini-review examines the advantages and limitations of specific techniques: proton induced X-ray emission (PIXE), X-ray fluorescence microscopy (XFM), secondary ion mass spectrometry (SIMS), laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and the sample preparation requirements to study diffusible ions with these methods.

Tracking elemental changes in an ischemic stroke model with X-ray fluorescence imaging

“…Our tissue preparation methods avoid the loss of mobile ions during perfusion or tissue fixation and preserve the in situ elemental levels and their gross distribution (see Methods) 13 . Brain tissue, for example, is high in K + , however, typical preparation methods (i.e.…”

Host–Guest Chemistry for Simultaneous Imaging of Endogenous Alkali Metals and Metabolites with Mass Spectrometry

“… 4 Imaging of elemental distributions can be achieved with techniques such as time-of-flight secondary ion mass spectrometry (TOF SIMS), 5 laser ablation inductively coupled plasma mass spectrometry (LA ICP MS), 6 X-ray fluorescence microscopy, 6 and proton-induced X-ray emission (PIXE). 6 For imaging of molecular distributions, several techniques have been developed, including matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS), 7 desorption electrospray ionization mass spectrometry (DESI MS), 8 and nanospray desorption electrospray ionization mass spectrometry (nano-DESI MS). 9 Recently, DESI followed by PIXE has been applied on the same tissue section in two experiments to obtain trace elements and molecular information on a single tissue section.…”

“…Spatially resolved information is of particular importance in biological systems to elucidate mechanisms of action involved in diseased states that lead to homeostasis perturbations . Imaging of elemental distributions can be achieved with techniques such as time-of-flight secondary ion mass spectrometry (TOF SIMS), laser ablation inductively coupled plasma mass spectrometry (LA ICP MS), X-ray fluorescence microscopy, and proton-induced X-ray emission (PIXE) . For imaging of molecular distributions, several techniques have been developed, including matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS), desorption electrospray ionization mass spectrometry (DESI MS), and nanospray desorption electrospray ionization mass spectrometry (nano-DESI MS) .…”

High-throughput single pixel spectral imaging system for glow discharge optical emission spectrometry elemental mapping enabled by compressed sensing

“…Mapping the distribution of elements in solid samples is critical for understanding the underlying mechanisms of natural and engineered materials. [1][2][3][4][5][6][7] There are several elemental mapping (EM) techniques currently available but, while they possess different advantages, a common limitation is long acquisition times, which can require several hours or more. Glow discharge optical emission spectroscopy (GDOES) has been shown to permit EM from within the sputtered area when operated in pulsed power mode and sustained under higher-than-typical pressures.…”