Exploring the potential of laser desorption ionisation time-of-flight mass spectrometry to analyse organic capping agents on inorganic nanoparticle surfaces
Open Access
- 16 June 2020
- journal article
- research article
- Published by Springer Science and Business Media LLC in Analytical and Bioanalytical Chemistry
- Vol. 412 (22), 5261-5271
- https://doi.org/10.1007/s00216-020-02740-3
Abstract
Analytical techniques are in high demand for the determination of organic capping agents on surfaces of metallic nanoparticles (NPs) such as gold (Au) and silver (Ag). In this study, the potential of laser desorption ionisation time-of-flight mass spectrometry (LDI-ToF-MS) as a technique fit for this purpose is demonstrated. First, a collection of reference spectra of most commonly used organic capping agents, including small molecules and polymers was established. Second, the robustness of the method was tested towards parameters like NP core material and NP size. In a third step, the quantitative capabilities of LDI-ToF-MS were determined. Finally, the potential to detect chemical alterations of the organic capping agent was evaluated. LDI-ToF-MS is able to detect capping agents ranging from small molecules (citric acid, tannic acid, lipoic acid) to large polymers (polyvinylpyrrolidone, branched polyethylenimine and methoxy polyethylene glycol sulfhydryl) on Au and Ag NPs based on characteristic signals for each capping agent. Small molecules showed characteristic fragment ions with low intensities, whereas polymers showed intense signals of the monomeric subunit. The NP concentration range comprises about two orders of magnitude with lowest detection limits of 5 mg/L or a capping agent concentration in the lower nM range. Changes in capping agent composition are detectable at NP concentrations in the g/L range. Thus, LDI-ToF-MS is particularly suitable for characterisation of polymer-capped NPs with high NP concentrations. This may be the case for quality control as part of the material synthesis and testing. Graphical abstractKeywords
Funding Information
- Helmholtz-Zentrum für Umweltforschung GmbH - UFZ
This publication has 36 references indexed in Scilit:
- Surface coating effects on the sorption and dissolution of ZnO nanoparticles in soilEnvironmental Science: Nano, 2019
- Biomedical applications of polyelectrolyte coated spherical gold nanoparticlesNano Convergence, 2019
- Characterization techniques for nanoparticles: comparison and complementarity upon studying nanoparticle propertiesNanoscale, 2018
- Characterization of Ligand Shell for Mixed-Ligand Coated Gold NanoparticlesAccounts of Chemical Research, 2017
- Nanoparticle decoration with surfactants: Molecular interactions, assembly, and applicationsSurface Science Reports, 2017
- Characterizing Self-Assembled Monolayers on Gold NanoparticlesBioconjugate Chemistry, 2016
- Particle Coating-Dependent Interaction of Molecular Weight Fractionated Natural Organic Matter: Impacts on the Aggregation of Silver NanoparticlesEnvironmental Science & Technology, 2015
- Transformations of Nanomaterials in the EnvironmentEnvironmental Science & Technology, 2012
- Engineered nanoparticle surfaces for improved mass spectrometric analysesThe Analyst, 2009
- Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry. Instrumentation and ApplicationsJournal of Chemical Education, 1997