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

摘要

It is becoming increasingly common to use gold nanoparticlesn(AuNPs) protected by a heterogeneous mixture ofnthiolate ligands, but many ligand mixtures on AuNPsncannot be properly characterized due to the inherentnlimitations of commonly used spectroscopic techniques.nUsing ion mobility-mass spectrometry (IM-MS), we havendeveloped a strategy that allows measurement of thenrelative quantity of ligands on AuNP surfaces. Thisnstrategy is used for the characterization of three samplesnof mixed-ligand AuNPs: tiopronin:glutathione (av diametern2.5 nm), octanethiol:decanethiol (av diameter 3.6nnm), and tiopronin:11-mercaptoundecyl(poly ethylenenglycol) (av diameter 2.5 nm). For validation purposes, thenresults obtained for tiopronin:glutathione AuNPs werencompared to parallel measurements using nuclear magneticnresonance (NMR) spectroscopy and mass spectrometryn(MS) without ion mobility separation. Relative quantitationnmeasurements for NMR and IM-MS were innexcellent agreement, with an average difference of lessnthan 1% relative abundance. IM-MS and MS without ionnmobility separation were not comparable, due to a lacknof ion signals for MS. The other two mixed-ligand AuNPsnprovide examples of measurements that cannot be performednusing NMR spectroscopy.