Single Cell Analysis Using Nanoscale Secondary Ion Mass Spectrometry

Dirk Schaumlöffel, a research scientist at the Université de Pau et des Pays de l'Adour in France presented his team’s work on single cell analysis using nanoscale secondary ion mass spectrometry (NanoSIMS) at the Winter Conference on Plasma Spectrochemistry on January 15 in Tucson, Arizona.

NanoSIMS is a high-resolution imaging technique for the localization of almost all chemical elements on a surface. The technique can be used to analyze biological tissue, cells, and biominerals, for example.

The technique can be used to analyze both hard material (cells, or tissue, for example) or hard material (eggshells or bone). To prepare the samples for analysis, they are first put through fixation, dehydration, and resin embedding. Soft materials are then put through ultramicrotome sectioning before being deposited on water. For hard materials, the sample is sectioned using a µm wire saw followed by polishing and gold coating. Then the sample is ready for surface analysis.

Schaumlöffel’s team used this process to screen eggshells, with the goal of developing a better understanding of how trace elements are incorporated into shells when consumed by hens. First, about 1,560 hens were supplemented with zinc (Zn), copper (Cu), and manganese (Mn). The team wanted to better understand how these elements contributed to the strength of eggshells.

“There’s an economic reason to keep the eggshells strong,” Schaumlöffel said. The stronger the eggshell, the less likely it is that bacteria will be able to penetrate the egg. Additionally, stronger eggshells are less likely to break during collection and transport.

The researchers analyzed the eggshells using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and NanoSIMS. Imaging showed the sufficient absorption of Zn, Cu, and Mn after supplementation of hens. Mn, Zn, and magnesium (Mg) were found in the outer membrane and cuticle of the eggshells.

Schaumlöffel’s team developed different correlative imaging approaches between LA-ICP-MS, NanoSIMS, andsynchrotron radiation-based Fourier transform infrared (SR-FT-IR), allowing, for example, a high-resolution zoom by NanoSIMS in selected areas of LA-ICP-MS images. The first results of quantitative NanoSIMS imaging allowed for the preparation of homogenous matrix-matched standards.