Real-time size discrimination and elemental analysis of gold nanoparticles using ES-DMA coupled to ICP-MS

Abstract

We report the development of a hyphenated instrument with the capacity to quantitatively characterize aqueous suspended gold nanoparticles (AuNPs) based on a combination of gas-phase size separation, particle counting, and elemental analysis. A customized electrospray-differential mobility analyzer (ES-DMA) was used to achieve real-time upstream size discrimination. A condensation particle counter and inductively coupled plasma mass spectrometer (ICP-MS) were employed as downstream detectors, providing information on number density and elemental composition, respectively, of aerosolized AuNPs versus the upstream size selected by ES-DMA. A gas-exchange device was designed and optimized to improve the conversion of air flow (from the electrospray) to argon flow required to sustain the ICP-MS plasma, the key compatibility issue for instrumental hyphenation. Our work provides the proof of concept and a working prototype for utilizing this construct to successfully measure (1) number- and mass-based distributions; (2) elemental compositions of nanoparticles classified by size, where the size classification and elemental analysis are performed within a single experiment; (3) particle concentrations in both solution (before size discrimination) and aerosol (after size discrimination) phases; and (4) the number of atoms per nanoparticle or the nanoparticle density.

Chemical Basis of Interactions Between Engineered Nanoparticles and Biological Systems

“…114 Strong interactions between these materials and proteins are derived from π-π stacking, hydrophobic and electrostatic interactions. 19,115,116 ENREF 36 Interactions between aromatic groups on carbon nanomaterials and aromatic or amine residues in proteins play a vital role in binding. 117 Therefore, nanoparticle-protein binding events depend on the carbon nanoparticles, the nature of proteins and microenvironmental factors, such as pH and ionic strength.…”

Mass spectrometry for the characterization and quantification of engineered inorganic nanoparticles

“…This separation coupled with MS detectors, has been widely employed to tackle structural and size problems in volatile and nonvolatile compounds [51]. Now, such hybrid technique is also starting to be exploited for NPs characterization [52,53].…”

“…Coupling of differential mobility to ICP-MS was evaluated for the analysis of gold NPs. The approach enabled NP gas-phase size separation, provided information about number-and mass-based NPs distributions and allowed the determination of the elemental compositions and the number of atoms per nanoparticle [53].…”

“…Recently, IMS specifically using a differential mobility analyzer (DMA), a technique typically developed for aerosol analysis, has been also investigated for the analysis of liquid nanoparticle suspensions, provided that the particles of interest can be aerosolized preserving their size distribution function [77]. Though this technique has been successfully applied to metal nanoparticles there are still drawbacks to using electrosprays for aerosolization (e.g.…”

Overview of Nanomaterial Characterization and Metrology

“…These applied aerosol techniques can provide much higher resolution separation and size distribution information as well as insight into the contribution of hydrated surfaces. 154 Although the number of hyphenation iterations with separation and detection is large, some hyphenated techniques have been particularly adept at separation and characterization over a significant portion of the nanorange and these techniques are further discussed in subsequent chapters.…”