Quantifying Ligand Adsorption to Nanoparticles Using Tandem Differential Mobility Mass Analysis

Abstract

Although electrospray-differential mobility analyzers (ES-DMA) have been previously employed to characterize ligand binding to nanoparticles, absolute quantification of surface coverage can be inaccurate at times because of ligand conformational effects. In this Letter, we report a quantitative technique by in-flight coupling of a particle mass analyzer (APM) with ES-DMA, thus enabling a direct quantitative analysis of mass independent of particle size, material, morphology and conformation. We demonstrate the utility of ES-DMA-APM by studying two model complex systems (gold nanoparticle-bovine serum albumin and polystyrene bead-antibody) as a function of concentration and pH. Our results obtained with ES-DMA-APM are in excellent agreement with prior work. We anticipate that this will enhance the capabilities of online quantitative characterization of ligand binding to nanoparticles.

Design Considerations and Performance Evaluation of a Compact Aerosol Particle Mass Analyzer

“…When the number of charges on a particle is known, the APM can determine the particle mass. The APM has been used, often in combination with a differential mobility analyzer (DMA), for evaluation of various particle properties such as "effective" density (McMurry et al 2002;Geller et al 2006;Malloy et al 2009;Liu et al 2012), morphology through estimation of the mass-mobility exponent (Park et al 2003a; Ku et al 2006;Kim et al 2009;Nakao et al 2011;Scheckman and McMurry 2011;Torvela et al 2011;Eggersdorfer et al 2012;Guha et al 2012;Ku and Evans 2012), the mixing ratio of internally-mixed particles (Sakurai et al 2003;Park et al 2008;Khalizov et al 2009;Ma and Zachariah 2009), material density (Park et al 2004;Kuwata et al 2012), particulate mass concentration (Park et al 2003b;Saito et al 2008), mass (Kuwata et al 2009;Lall et al 2009), volume (Lall et al 2008), and porosity (Lee et al 2011). The APM can also be used as a generator of particles having a specified mass (Malik et al 2011;Moteki et al 2011;Laborde et al 2012;Beranek et al 2012).…”

Functionalized gold nanoparticles for sample preparation: A review

“…If aggregated particles in the colloidal solution would be considered as well, an overestimation of protein coverage would be caused. Another technique, in‐flight coupling of the particle mass analyzer (PMA) with electrospray‐differential mobility analyzers (DMA) allows the quantitative analysis of particle masses . As outlined in this paper, the PMA aerosol particle analyzer is a fundamental mass measurement device that determines mass by a balance of electrical and centrifugal forces.…”

Advantages and limitations of nanoparticle labeling for early diagnosis of infection

“…The same tool, inductively-coupled plasma-mass spectrometry (ICP-MS), can be applied to bulk compositional analysis as well as to some types of surface modifiers. [126][127][128] Other approaches to the analysis of surface modifiers and MREs include spectrophotometric depletion measurements, differential mobility mass analysis, and surface infrared and/or Raman spectroscopies. Particle size and shape present a different level of complexity.…”

“…EA involves the quantitative determination of the Downloaded by [University of California Santa Barbara] at 15:15 23 June 2016stoichiometric ratios of carbon, hydrogen, nitrogen, various heteroatoms (e.g., sulfur and the halogens), and any isotopes. Molecular structure analysis, on the other hand, entails a determination of molecular weight by mass spectrometry (MS), functional groups by infrared spectroscopy (IRS) and nuclear magnetic resonance (NMR), as well as crystal structure by X-ray crystallography [121][122][123][124][125][126][127]. These are followed by purity determinations using gas (GC) or liquid (LC) chromatography, which may be coupled downstream with MS.…”