versatile-dual-inlet-sample-introduction-system-for-multi-mode-single

Versatile Dual-Inlet Sample Introduction System for Multi-Mode Single Particle Inductively Coupled Plasma Mass Spectrometry Analysis and Validation

Metal-containing nanoparticles (NP) can be characterized with inductively coupled plasma mass spectrometers (ICP-MS) in terms of their size and number ...

SPETEC GmbH

We have efficiently produced collagen-rich microstructures in fibroblast multicellular spheroids (MCSs) as a three-dimensional in vitro tissue analog to investigate silver (Ag) nanoparticle (NP) penetration. The MCS production was examined by changing the seeding cell number (500 to 40,000 cells) and the growth period (1 to 10 days). MCSs were incubated with Ag NP suspensions with a concentration of 5 μg mL for 24 h. For this study, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to visualize Ag NP localization quantitatively. Thin sections of MCSs were analyzed by LA-ICP-MS with a laser spot size of 8 μm to image distributions of Ag, P, Cu, Zn, and Br. A calibration using a NP suspension was applied to convert the measured Ag intensity into the number of NPs present. The determined numbers of NPs ranged from 30 to 7200 particles in an outer rim of MCS. The particle distribution was clearly correlated with the presence of P and Zn and was localized in the outer rim of proliferating cells with a width that was equal to about twice the diameter of single cells. Moreover, abundant collagens were found in the outer rim of MCSs. For only the highest seeding cell number, NPs were completely captured at the outer rim, in a natural barrier reducing particle transport, whereas Eosin (Br) used as a probe of small molecules penetrated into the core of MCSs already after 1 min of exposure. Graphical abstract Fibroblast MCS could build up the barrier only for nanoparticles.

High-resolution laser ablation inductively coupled plasma mass spectrometry used to study transport of metallic nanoparticles through collagen-rich microstructures in fibroblast multicellular spheroids.

We applied high resolution laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOF-MS) with cellular spatial resolution for bioimaging of nanoparticles uptaken by fibroblast multicellular spheroids (MCS). This was used to quantitatively investigate interactions of silver nanoparticles (Ag NPs) and the distributions of intrinsic minerals and biologically relevant elements within thin sections of a fibroblast MCS as a three-dimensional  tissue model. We designed matrix-matched calibration standards for this purpose and printed them using a noncontact piezo-driven array spotter with a Ag NP suspension and multielement standards. The limits of detection for Ag, Mg, P, K, Mn, Fe, Co, Cu, and Zn were at the femtogram (10 g) level, which is sufficient to investigate intrinsic minerals in thin MCS sections (20 μm thick). After incubation for 48 h, Ag NPs were enriched in the outer rim of the MCS but not detected in the core. The localization of Ag NPs was inhomogeneous in the outer rim, and they were colocalized with a single-cell-like structure visualized by Fe distribution (pixel size of elemental images: 5 × 0.5 μm). The quantitative value for the total mass of Ag NPs in a thin section by the present method agreed with that obtained by ICP-sector field (SF)-MS with a liquid mode after acid digestion.

Quantitative Imaging of Silver Nanoparticles and Essential Elements in Thin Sections of Fibroblast Multicellular Spheroids by High Resolution Laser Ablation Inductively Coupled Plasma Time-of-Flight Mass Spectrometry.

In the last decades, significant efforts have been made to investigate possible cytotoxic effects of metallic nanoparticles (NPs). Methodologies enabling precise information regarding uptake and intracellular distribution of NPs at the single cell level remain to be established. Mass cytometry (MC) has been developed for high-dimensional single cell analyses and is a promising tool to quantify NP-cell interactions. Here, we aim to establish a new MC-based quantification procedure to receive absolute numbers of NPs per single cell by using a calibration that considers the specific transmission efficiency (TE) of suspended NPs. The current MC-quantification strategy accept TE values of complementary metal solutions. In this study, we demonstrate the different transmission behavior of 50 nm silver NPs (AgNP) and silver nitrate solution. We have used identical AgNPs for calibration as for -differentiated macrophages (THP-1 cell line) in a time- and dose-dependent manner. Our quantification relies on silver intensities measuring AgNPs in the same detection mode as the cells. Results were comparable with the TE quantification strategy using AgNPs but differed when using ionic silver. Furthermore, intact and digested cell aliquots were measured to investigate the impact of MC sample processing on the amount of AgNPs/cell. Taken together, we have provided a MC-specific calibration procedure to precisely calculate absolute numbers of NPs per single cell. Combined with its unique feature of multiplexing up to 50 parameters, MC provides much more information on the single cell level than single cell-inductively coupled plasma mass spectrometry (SC-ICPMS) and, therefore, offers new opportunities in nanotoxicology.

Mass Cytometry Enabling Absolute and Fast Quantification of Silver Nanoparticle Uptake at the Single Cell Level.

Immunohistochemistry techniques represent a powerful tool to detect and quantify disease related proteins. Improvements were accomplished by tagged antibodies using laser ablation and inductively coupled plasma mass spectrometry (LA-ICP-MS). However, these approaches are effected by day-to-variations due to instrumental drift.

Multiplex LA-ICP-MS bio-imaging of brain tissue of a parkinsonian mouse model stained with metal-coded affinity-tagged antibodies and coated with indium-spiked commercial inks as internal standards.

This study reports on the development of a single-particle (sp) inductively coupled plasma mass spectrometry (ICP-MS) technique suitable for the multi-mode determination of nanoparticle (NP) metal mass fraction and number concentration. The described technique, which is based on a dual inlet system consisting of a pneumatic nebulizer (PN) and a microdroplet generator (MDG), allows for the sequential introduction of ionic metal calibrant solutions and nanoparticle suspensions via all combinations of the two inlets; thus allowing for a combination of three independent modes of analysis. A novel interface, assembled using standard analytical components (a demountable quartz ICP-MS torch, flexible non-conducting silicon tubing and various connectors), was used to interface the dual inlet system to an ICP-MS. The interface provided improved functionality, compared to a previous design. It is now possible to conveniently exchange and introduce standard solutions and samples via all inlet combinations, analyze them, and also wash the sample inlet systems while the whole setup is still connected to an operating ICP-MS. This setup provided seamless and robust operation in a total of three analysis modes, i.e. three ways to independently determine the metal mass fraction and NP number concentration. All three analyses modes could be carried out within a single analytical run lasting approximately 20 min. The unique feature of the described approach is that each analysis mode is based on a different calibration principle, thus constituting an independent way to determine metal mass fractions and nanoparticle number concentrations. Conducting the three independent state-of-the-art analysis, within a single analytical run, improves substantially the validation capabilities of sp-ICP-MS for NP analysis. To assess the technique's analytical performance, Au, Ag and CeO nanoparticles were analyzed. The determined average diameters for Au (56.7 ± 1.5 nm), Ag (72.8 ± 3.4 nm) and CeO (69.0 ± 6.4 nm) NPs were in close agreement for all three modes of analysis, as well as with the values provided by suppliers' for Au and Ag NPs (56.0 ± 0.5 for Au, 74.6 ± 3.8 nm for Ag). However, the determined average value for CeO was much higher than the expected 28.4 ± 10.4 nm, possibly due to NP agglomeration and the inability to detect NPs existing within the lower size range. The determined NP number concentrations, using analysis modes -I and -II, gave recoveries between 91 and 100% for the Au and Ag NP number concentrations. Whereas analysis mode -III showed a recovery of 70-88% for the same materials. Because of the polydispersity, the small size and polyhedral shape of the CeO NPs it was not possible to make NP number concentration comparisons for this material.

Improved validation for single particle ICP-MS analysis using a pneumatic nebulizer / microdroplet generator sample introduction system for multi-mode nanoparticle determination.

Nano-carrier systems such as liposomes have promising biomedical applications. Nevertheless, characterization of these complex samples is a challenging analytical task. In this study a coupled hydrodynamic chromatography-single particle-inductively coupled plasma mass spectrometry (HDC-spICP-MS) approach was validated based on the technical specification (TS) 19590:2017 of the international organization for standardization (ISO). The TS has been adapted to the hyphenated setup. The quality criteria (QC), e.g., linearity of the calibration, transport efficiency, were investigated. Furthermore, a cross calibration of the particle size was performed with values from dynamic light scattering (DLS) and transmission electron microscopy (TEM). Due to an additional Y-piece, an online-calibration routine was implemented. This approach allows the calibration of the ICP-MS during the dead time of the chromatography run, to reduce the required time and enhance the robustness of the results. The optimized method was tested with different gold nanoparticle (Au-NP) mixtures to investigate the characterization properties of HDC separations for samples with increasing complexity. Additionally, the technique was successfully applied to simultaneously determine both the hydrodynamic radius and the Au-NP content in liposomes. With the established hyphenated setup, it was possible to distinguish between different subpopulations with various NP loads and different hydrodynamic diameters inside the liposome carriers.

Tackling Complex Analytical Tasks: An ISO/TS-Based Validation Approach for Hydrodynamic Chromatography Single Particle Inductively Coupled Plasma Mass Spectrometry.

Norbert Jakubowski

SPETEC GmbH

Versatile Dual-Inlet Sample Introduction System for Multi-Mode Single Particle Inductively Coupled Plasma Mass Spectrometry Analysis and Validation