A Structural Mass Spectrometry Strategy for the Relative Quantitation of Ligands on Mixed Monolayer-Protected Gold Nanoparticles

It is becoming increasingly common to use gold nanoparticles (AuNPs) protected by a heterogeneous mixture of thiolate ligands, but many ligand mixtures on AuNPs cannot be properly characterized due to the inherent limitations of commonly used spectroscopic techniques. Using ion mobility−mass spectro...

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Bibliographic Details
Published in:Analytical chemistry (Washington) 2010-11, Vol.82 (22), p.9268-9274
Main Authors: Harkness, Kellen M, Hixson, Brian C, Fenn, Larissa S, Turner, Brian N, Rape, Amanda C, Simpson, Carrie A, Huffman, Brian J, Okoli, Tracy C, McLean, John A, Cliffel, David E
Format: Article
Language:English
Subjects:
Analytical chemistry
Chemistry
Exact sciences and technology
Glutathione - chemistry
Gold
Gold - chemistry
Hydrophobic and Hydrophilic Interactions
Ions
Ligands
Magnetic Resonance Spectroscopy
Mass spectrometry
Mass Spectrometry - methods
Metal Nanoparticles - chemistry
Molecules
Nanoparticles
Polyethylene Glycols - chemistry
Spectrometric and optical methods
Sulfhydryl Compounds - chemistry
Surface Properties
Tiopronin - chemistry
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Summary:It is becoming increasingly common to use gold nanoparticles (AuNPs) protected by a heterogeneous mixture of thiolate ligands, but many ligand mixtures on AuNPs cannot be properly characterized due to the inherent limitations of commonly used spectroscopic techniques. Using ion mobility−mass spectrometry (IM-MS), we have developed a strategy that allows measurement of the relative quantity of ligands on AuNP surfaces. This strategy is used for the characterization of three samples of mixed-ligand AuNPs: tiopronin:glutathione (av diameter 2.5 nm), octanethiol:decanethiol (av diameter 3.6 nm), and tiopronin:11-mercaptoundecyl(poly ethylene glycol) (av diameter 2.5 nm). For validation purposes, the results obtained for tiopronin:glutathione AuNPs were compared to parallel measurements using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) without ion mobility separation. Relative quantitation measurements for NMR and IM-MS were in excellent agreement, with an average difference of less than 1% relative abundance. IM-MS and MS without ion mobility separation were not comparable, due to a lack of ion signals for MS. The other two mixed-ligand AuNPs provide examples of measurements that cannot be performed using NMR spectroscopy.
ISSN:0003-2700
1520-6882
DOI:10.1021/ac102175z