title: Competitive adsorption of thiolated polyethylene glycol and mercaptopropionic acid on gold nanoparticles measured by physical characterization methods.
abstract: Competitive adsorption kinetics between thiolated polyethylene glycol (SH-PEG) and mercaptopropionic acid (MPA) on gold nanoparticles (Au-NPs) were studied using a prototype physical characterization approach that combines dynamic light scattering (DLS) and electrospray differential mobility analysis (ES-DMA). The change in hydrodynamic particle size (intensity average) due to the formation of SH-PEG coatings on Au-NPs was measured by DLS in both two-component (Au-NP + MPA or Au-NP + SH-PEG) and three-component (Au-NP +MPA + SH-PEG) systems. ES-DMA was employed to quantify the surface coverage of SH-PEG and establish a correlation between surface coverage and the change in particle size measured by DLS. A change in the equilibrium binding constant for SH-PEG on Au-NPs at various concentrations of SH-PEG and MPA showed that the presence of MPA reduced the binding affinity of SH-PEG to the Au-NP surface. Kinetic studies showed that SH-PEG was desorbed from the Au-NP surface following a second-order desorption model after subsequently introducing MPA. The desorption rate constant of SH-PEG from the Au-NP surface by MPA displacement was strongly affected by the concentration of MPA and the excess SH-PEG in solution.
authors.affiliation: Ceramics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
authors.forename: De-Hao
authors.initials: DH
authors.lastname: Tsai
authors.forename: Frank W
authors.initials: FW
authors.lastname: DelRio
authors.forename: Robert I
authors.initials: RI
authors.lastname: MacCuspie
authors.forename: Tae Joon
authors.initials: TJ
authors.lastname: Cho
authors.forename: Michael R
authors.initials: MR
authors.lastname: Zachariah
authors.forename: Vincent A
authors.initials: VA
authors.lastname: Hackley
mesh_terms: D000327:Adsorption; D006046:Gold; D007700:Kinetics; D053768:Metal Nanoparticles / Q000737:chemistry*; D008722:Methods; D011092:Polyethylene Glycols / Q000737:chemistry*; D011422:Propionates / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D011422:Propionates; D013438:Sulfhydryl Compounds; D011092:Polyethylene Glycols; D006046:Gold
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