A simple metal staining procedure for identification and visualization of single cells by LA-ICP-MS

Abstract

High lateral resolution of metal detection in single cells by use of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) demands powerful staining methods. In this work different staining procedures for the single cell analysis with LA-ICP-MS were optimized. An iridium intercalator was utilized to stain the cell nuclei whereas the whole cell was stained by the use of maleimido-mono-amide-DOTA (mDOTA) complexing lanthanide(iii) ions. The content of the artificially introduced metals per cell was quantified using a matrix matched calibration approach based on cellulose membranes onto which standards were spotted by a microarray spotter. Absolute metal stain amounts in the range of 2.34 to 9.81 femtomole per cell were determined. The metal staining procedures allow direct identification and visualization of single cells and their cell compartments by element microscopy without the use of bright field images of the sample.

Recent advances in LA-ICP-MS for biomedical applications

“…LA-ICP-MS is being proposed as an elemental microscopy technique, since it has quantitative features when matrix-matched calibration standards are used, besides the ease of sample preparation and multielemental detection capabilities with high sensitivity and spatial resolution. For co-localization of cells and analytes, LA-ICP-MS profiles are usually correlated with a bright field image of the cell sample [20] or other imaging approaches, such as fluorescence confocal microscopy [37]; thus, multimodal imaging is widely applied for single cell elemental analysis.…”

“…A limiting point of using LA-ICP-MS at micrometer scale is the reduced laser spot size, which leads to a reduction of ablated sample material and therefore to a decreased number of detectable ions in the analyzed area, thus resulting in a compromise between sensitivity and spot size [20]. Another limitation of the single cell LA-ICP-MS imaging is the depth resolution, since the laser beam penetrates through the entire cell, and the signal from the cytosol is monitored together with the nucleus [39].…”

Isotopically Enriched Tracers and Inductively Coupled Plasma Mass Spectrometry Methodologies to Study Zinc Supplementation in Single-Cells of Retinal Pigment Epithelium in Vitro

“…For characterization of single-cells by LA-ICP-MS imaging, the use of metal staining reagents for cell localization was previously reported. 20,24 In our experiments, Fig. 3a shows the microscope image of the selected area, distinguishing the cells from the glass substrate of the chamber-slide.…”

“…single metal chelates such as DOTA lanthanide complexes and polymeric labels such as MAXPAR®) were investigated for imaging of proteins within single cells. 14,20,23,24 Furthermore, some strategies based on standards spotted onto nitrocellulose membranes or microarray gelatin standards were used to obtain not only elemental qualitative distributions but also quantitative information from cell cultures. 14,25 The aim of our investigation was to evaluate the Zn absorption in cultured HRPEvs cells after its supplementation with isotopically-enriched tracers ( t68 Zn and t70 Zn).…”

Critical evaluation of fast and highly resolved elemental distribution in single cells using LA-ICP-SFMS

“…This high speed and high spatial resolution LA-ICP-SFMS method is investigated for the determination of elemental distributions within single cells, which is crucial to study intracellular and intercellular processes as well as their function in a cell system (e.g. tissue or organ) [19][20][21]. Distribution and visualization of the cellular uptake of gold nanoparticles (Au NPs) and Cd-based quantum dots (QDs) in two established cell lines, such as mouse embryonic fibroblast cells (NIH/3T3 fibroblast cells) and human cervical carcinoma cells (HeLa cells), are here investigated.…”