Cryo-XPS for Surface Characterization of Nanomedicines.

Nanoparticles used for medical applications commonly possess coatings or surface functionalities intended to provide specific behavior , for example, the use of PEG to provide stealth properties. Direct, quantitative measurement of the surface chemistry and composition of such systems in a hydrated environment has thus far not been demonstrated, yet such measurements are of great importance for the development of nanomedicine systems. Here we demonstrate the first use of cryo-XPS for the measurement of two PEG-functionalized nanomedicines: a polymeric drug delivery system and a lipid nanoparticle mRNA carrier.

Quantitative and Qualitative Analyses of Mass Spectra of OEL Materials by Artificial Neural Network and Interface Evaluation: Results from a VAMAS Interlaboratory Study.

Quantitative analysis of binary mixtures of tris(2-phenylpyridinato)iridium(III) (Ir(ppy)) and tris(8-hydroxyquinolinato)aluminum (Alq) by using an artificial neural network (ANN) system to mass spectra was attempted based on the results of a VAMAS (Versailles Project on Advanced Materials and Standards) interlaboratory study (TW2 A31) to evaluate matrix-effect correction and to investigate interface determination. Monolayers of binary mixtures having different Ir(ppy) ratios (0, 0.25, 0.

Surface Analysis of Pristine and Cycled NMC/Graphite Lithium-Ion Battery Electrodes: Addressing the Measurement Challenges.

Lithium-ion batteries are the most ubiquitous energy storage devices in our everyday lives. However, their energy storage capacity fades over time due to chemical and structural changes in their components, via different degradation mechanisms. Understanding and mitigating these degradation mechanisms is key to reducing capacity fade, thereby enabling improvement in the performance and lifetime of Li-ion batteries, supporting the energy transition to renewables and electrification.

Molecular Formula Prediction for Chemical Filtering of 3D OrbiSIMS Datasets.

Modern mass spectrometry techniques produce a wealth of spectral data, and although this is an advantage in terms of the richness of the information available, the volume and complexity of data can prevent a thorough interpretation to reach useful conclusions. Application of molecular formula prediction (MFP) to produce annotated lists of ions that have been filtered by their elemental composition and considering structural double bond equivalence are widely used on high resolving power mass spectrometry datasets. However, this has not been applied to secondary ion mass spectrometry data.

Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles.

We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol.

Method for Molecular Layer Deposition Using Gas Cluster Ion Beam Sputtering with Example Application Matrix-Enhanced Secondary Ion Mass Spectrometry.

We introduce a technique for the directed transfer of molecules from an adjacent reservoir onto a sample surface inside the vacuum chamber of a ToF-SIMS instrument using gas cluster ion beam (GCIB) sputtering. An example application for matrix-enhanced secondary ion mass spectrometry (ME SIMS) is provided. This protocol has attractive features since most modern SIMS instruments are equipped with a GCIB gun.

Protein identification by 3D OrbiSIMS to facilitate in situ imaging and depth profiling.

Label-free protein characterization at surfaces is commonly achieved using digestion and/or matrix application prior to mass spectrometry. We report the assignment of undigested proteins at surfaces in situ using secondary ion mass spectrometry (SIMS). Ballistic fragmentation of proteins induced by a gas cluster ion beam (GCIB) leads to peptide cleavage producing fragments for subsequent Orbitrap analysis.

Measurement of Peptide Coating Thickness and Chemical Composition Using XPS.

X-ray photoelectron spectroscopy is a highly surface-sensitive analytical technique, capable of providing quantitative information on the chemical composition of materials within the top ∼10 nm of their surface. For samples consisting of distinct underlayer and overlayer materials, the thickness of the coating can also be determined if it falls within this ∼10 nm information depth, which is often the case for peptide layers. Such measurements are simple to perform for flat samples and can also be performed on nanoparticulate samples provided that either the core radius or total particle radius are known.

Practical Guides for X-Ray Photoelectron Spectroscopy (XPS): First Steps in planning, conducting and reporting XPS measurements.

Over the past three decades, the widespread utility and applicability of X-ray photoelectron spectroscopy (XPS) in research and applications has made it the most popular and widely used method of surface analysis. Associated with this increased use has been an increase in the number of new or inexperienced users which has led to erroneous uses and misapplications of the method. This article is the first in a series of guides assembled by a committee of experienced XPS practitioners that are intended to assist inexperienced users by providing information about good practices in the use of XPS.

Correction: Schavkan, A., Number Concentration of Gold Nanoparticles in Suspension: SAXS and spICPMS as Traceable Methods Compared to Laboratory Methods. 2019, , 502.

The authors wish to make the following corrections to this paper [...

Sticky Measurement Problem: Number Concentration of Agglomerated Nanoparticles.

Measuring the number concentration of colloidal nanoparticles (NPs) is critical for assessing reproducibility, enabling compliance with regulation, and performing risk assessments of NP-enabled products. For nanomedicines, their number concentration directly relates to their dose. However, the lack of relevant reference materials and established traceable measurement approaches make the validation of methods for NP number concentration difficult.

Robust and accurate measurements of gold nanoparticle concentrations using UV-visible spectrophotometry.

This paper provides an empirical formula to calculate the extinction efficiencies of gold nanoparticles over the size range 1-1000 nm in fluids with refractive indexes which extend from  = 1 to  = 1.62. The formula contains a shape factor to account for nonspherical particles and aggregates.

Peptide engineered microcantilevers for selective chemical force microscopy and monitoring of nanoparticle capture.

Engineered peptides capable of binding to silica have been used to provide contrast in chemical force microscopy and tested for their capacity to selectively capture silica nanoparticles (NPs). Gold coated atomic force microscopy (AFM) microcantilevers with integrated tips and colloidal probes were functionalized with engineered peptides through a thiol group of a terminal cysteine which was linked via a glycine trimer to a 12-mer binding sequence. The functionalized probes demonstrated a significantly increased binding force on silicon oxide areas of a gold-patterned silicon wafer, whereas plain gold probes, and those functionalized with a random permutation of the silica binding peptide motif or an all-histidine sequence displayed similar adhesion forces to gold and silicon oxide.

Chemical measurements of polyethylene glycol shells on gold nanoparticles in the presence of aggregation.

Understanding and controlling the performance of engineered nanoparticle (NP) systems is greatly assisted by quantitative characterization of their coatings. Useful measurements methods have been described for NPs in liquid environment, but NP aggregation often represents a limiting factor which impairs the accuracy of techniques such as dynamic light scattering for quantification purposes. Here, the authors show how differential centrifugal sedimentation (DCS) and x-ray photoelectron spectroscopy (XPS) can provide quantitative information on the NP coating thickness, molecular conformation, and grafting density of aggregated NP samples.

Multitechnique characterization of oligo(ethylene glycol) functionalized gold nanoparticles.

Gold nanoparticles (AuNPs) with average diameters of ∼14 and ∼40 nm, as well as flat gold coated silicon wafers, were functionalized with oligo ethylene glycol (OEG) terminated 1-undecanethiol (HS-CH) self-assembled monolayers (SAMs). Both hydroxyl [(OEG)OH] and methoxy [(OEG)OMe] terminated SAMs were prepared. The AuNPs were characterized with transmission electron microscopy (TEM), time of flight secondary ion mass spectrometry (ToF-SIMS), x-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier infrared spectroscopy (ATR-FTIR), and low-energy ion scattering (LEIS).

Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS.

We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) inter-laboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and; particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS).

A Technique for Calculation of Shell Thicknesses for Core-Shell-Shell Nanoparticles from XPS Data.

This paper extends a straightforward technique for the calculation of shell thicknesses in core-shell nanoparticles to the case of core-shell-shell nanoparticles using X-ray Photoelectron Spectroscopy (XPS) data. This method can be applied by XPS analysts and does not require any numerical simulation or advanced knowledge, although iteration is required in the case where both shell thicknesses are unknown. The standard deviation in the calculated thicknesses simulated values is typically less than 10%, which is the uncertainty of the electron attenuation lengths used in XPS analysis.

Size and ζ-Potential Measurement of Silica Nanoparticles in Serum Using Tunable Resistive Pulse Sensing.

The contact of nanoparticles with biological fluids such as serum results in rapid adsorption of proteins at the nanoparticle surface in a layer known as the "protein corona". Protein coatings modify and control the behavior of the nanoparticles potentially altering the aggregation state and cellular response, which may influence their fate and hazard to human health. Cells are likely to interact with the protein interface rather than with bare surface; therefore it is important to study the protein layer and develop appropriate measurement tools.