title: Laser desorption/ionization mass spectrometry analysis of monolayer-protected gold nanoparticles.
abstract: Monolayer-protected gold nanoparticles (AuNPs) feature unique surface properties that enable numerous applications. Thus, there is a need for simple, rapid, and accurate methods to confirm the surface structures of these materials. Here, we describe how laser desorption/ionization mass spectrometry (LDI-MS) can be used to characterize AuNPs with neutral, positively, and negatively charged surface functional groups. LDI readily desorbs and ionizes the gold-bound ligands to produce both free thiols and disulfide ions in pure and complex samples. We also find that LDI-MS can provide a semi-quantitative measure of the ligand composition of mixed-monolayer AuNPs by monitoring mixed disulfide ions that are formed. Overall, the LDI-MS approach requires very little sample, provides an accurate measure of the surface ligands, and can be used to monitor AuNPs in complex mixtures.
authors.affiliation: Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Yan
authors.forename: Zheng-Jiang
authors.initials: ZJ
authors.lastname: Zhu
authors.forename: Oscar R
authors.initials: OR
authors.lastname: Miranda
authors.forename: Apiwat
authors.initials: A
authors.lastname: Chompoosor
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Rotello
authors.forename: Richard W
authors.initials: RW
authors.lastname: Vachet