scholarly journals Distribution of Paramagnetic Fe2O3/SiO2–Core/Shell Nanoparticles in the Rat Lung Studied by Time-of-Flight Secondary Ion Mass Spectrometry: No Indication for Rapid Lipid Adsorption

Nanomaterials ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 571 ◽  
Author(s):  
Lothar Veith ◽  
Antje Vennemann ◽  
Daniel Breitenstein ◽  
Carsten Engelhard ◽  
Birgit Hagenhoff ◽  
...  

Amorphous silica nanoparticles comprise a class of widely used industrial nanomaterials, which may elicit acute inflammation in the lung. These materials have a large specific surface to which components of the pulmonary micro-milieu can bind. To conduct appropriate binding studies, paramagnetic Fe2O3/SiO2 core/shell nanoparticles (Fe-Si-NP) may be used as an easy-to-isolate silica surrogate, if several prerequisites are fulfilled. To this end, we investigated the distribution of Fe, Si, protein and phosphatidylcholine (PC) by Time-of-Flight secondary ion mass spectrometry (ToF-SIMS) in cryo-sections from the rat lungs to which Fe-Si-NP had been administered for 30 min. Regions-of-interest were identified and analyzed with incident light and enhanced dark-field microscopy (DFM). Fe-Si-NP particles (primary particle size by electron microscopy: 10–20 nm; aggregate size by tracking analysis: 190 ± 20 nm) and agglomerates thereof were mainly attached to alveolar walls and only marginally internalized by cells such as alveolar macrophages. The localization of Fe-Si-NP by DFM was confirmed by ToF-SIMS signals from both, Fe and Si ions. With respect to an optimized signal-to-noise ratio, Fe+, Si+, CH4N+ and the PC head group (C5H15NO4P+) were the most versatile ions to detect iron, silica, protein, and PC, respectively. Largely congruent Fe+ and Si+ signals demonstrated that the silica coating of Fe-Si-NP remained stable under the conditions of the lung. PC, as a major lipid of the pulmonary surfactant, was colocalized with the protein signal alongside alveolar septa, but was not detected on Fe-Si-NP, suggesting that silica nanoparticles do not adsorb lipids of the lung surfactant under native conditions. The study shows that ToF-SIMS is a valuable technique with adequate spatial resolution to analyze nanoparticles together with organic molecules in the lung. The paramagnetic Fe-Si-NP appear well suited to study the binding of proteins to silica nanomaterials in the lung.

Author(s):  
Bruno Schueler ◽  
Robert W. Odom

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides unique capabilities for elemental and molecular compositional analysis of a wide variety of surfaces. This relatively new technique is finding increasing applications in analyses concerned with determining the chemical composition of various polymer surfaces, identifying the composition of organic and inorganic residues on surfaces and the localization of molecular or structurally significant secondary ions signals from biological tissues. TOF-SIMS analyses are typically performed under low primary ion dose (static SIMS) conditions and hence the secondary ions formed often contain significant structural information.This paper will present an overview of current TOF-SIMS instrumentation with particular emphasis on the stigmatic imaging ion microscope developed in the authors’ laboratory. This discussion will be followed by a presentation of several useful applications of the technique for the characterization of polymer surfaces and biological tissues specimens. Particular attention in these applications will focus on how the analytical problem impacts the performance requirements of the mass spectrometer and vice-versa.


2020 ◽  
Author(s):  
Feifei Jia ◽  
Jie Wang ◽  
Yanyan Zhang ◽  
Qun Luo ◽  
Luyu Qi ◽  
...  

<p></p><p><i>In situ</i> visualization of proteins of interest at single cell level is attractive in cell biology, molecular biology and biomedicine, which usually involves photon, electron or X-ray based imaging methods. Herein, we report an optics-free strategy that images a specific protein in single cells by time of flight-secondary ion mass spectrometry (ToF-SIMS) following genetic incorporation of fluorine-containing unnatural amino acids as a chemical tag into the protein via genetic code expansion technique. The method was developed and validated by imaging GFP in E. coli and human HeLa cancer cells, and then utilized to visualize the distribution of chemotaxis protein CheA in E. coli cells and the interaction between high mobility group box 1 protein and cisplatin damaged DNA in HeLa cells. The present work highlights the power of ToF-SIMS imaging combined with genetically encoded chemical tags for <i>in situ </i>visualization of proteins of interest as well as the interactions between proteins and drugs or drug damaged DNA in single cells.</p><p></p>


1996 ◽  
Vol 122 (1-2) ◽  
pp. 1-15 ◽  
Author(s):  
Keyang Xu ◽  
Andrew Proctor ◽  
David M. Hercules

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