High resolution imaging and 3D analysis of Ag nanoparticles in cells with ToF-SIMS and delayed extraction

Abstract

Within this study, the authors use human mesenchymal stem cells incubated with silver nanoparticles (AgNPs) as a model system to systematically investigate the advantages and drawbacks of the fast imaging delayed extraction mode for two-dimensional and three-dimensional (3D) analyses at the cellular level. The authors compare the delayed extraction mode with commonly employed measurement modes in terms of mass and lateral resolution, intensity, and dose density. Using the delayed extraction mode for single cell analysis, a high mass resolution up to 4000 at m/z = 184.08 combined with a lateral resolution up to 360 nm is achieved. Furthermore, the authors perform 3D analyses with Ar-clusters (10 keV) and O (500 eV) as sputter species, combined with Bi and delayed extraction for analysis. Cell compartments like the nucleus are visualized in 3D, whereas no realistic 3D reconstruction of intracellular AgNP is possible due to the different sputter rates of inorganic and organic cell materials. Furthermore, the authors show that the sputter yield of Ag increases with the decreasing Ar-cluster size, which might be an approach to converge the different sputter rates.

Multimodal Imaging Based on Vibrational Spectroscopies and Mass Spectrometry Imaging Applied to Biological Tissue: A Multiscale and Multiomics Review

“…This development has allowed the investigation of smaller features in biological materials with a sub-µm analysis beam with reasonable mass resolution. 101 Recently, it was shown possible to visualize the copper distribution in cells, 102 and the 3D distribution of Ag nanoparticles in cells 103 thanks to the combination of ToF-SIMS and DE. Tandem MS. One problem of using ToF-SIMS is the ambiguity when assigning a molecule to a certain mass peak.…”

Three dimensional secondary ion mass spectrometry imaging (3D-SIMS) of Aedes aegypti ovarian follicles

“…Other MSI techniques using laser sources can provide a higher spatial resolution (10-50 μm or down to few μm using special arrangements [13]) at ambient or vacuum conditions, but typically require the coating of the biological surfaces with a matrix (i.e., MALDI [14][15][16]); the matrix choice and application method determine the selectivity of analytes and the crystal size can become the limiting factor of the spatial resolution [16,17]. For MSI lipid analysis with high spatial resolution (<1 μm) [18][19][20][21], ion beams are typically used under vacuum conditions [22] without the need of surface treatment (i.e., secondary ion mass spectrometry, SIMS) [23]; SIMS spatial resolution and secondary ion yield varies with the projectile size (e.g., from atomic to poly-atomic to cluster beams) and incident energy. [24][25][26][27][28][29][30][31][32][33] Lipid MSI has been mainly performed by 2D imaging of subsequent sample sections, with consequent loss of 3D information due to the thickness of each slide (typically tens of μm).…”

Water repellency decreases with increasing carbonate content and pH for different biocrust types on sand dunes

“…The mass images shown in Fig. 4 were recorded in imaging mode with delayed extraction for good mass and good lateral resolution (Henss et al, 2018). For the images, areas of 500 x 500 µm 2 with 1024 x 1024 pixels were scanned.…”