We demonstrate a high-resolution, quantitative approach for the characterization of the stability of silver nanoparticles (AgNPs) conjugated with thiolated polyethylene glycol (SH-PEG). Using the time-resolved gas-phase ion-mobility and mass analyses, the extents of aggregation and surface dissolution of AgNPs, as well as the amount of SH-PEG adsorbed to or desorbed from AgNPs, were able to be identified simultaneously in the aerosol state. The results show that the SH-PEG with a molecular mass of 6 kg/mol (SH-PEG6K) was able to adsorb to the surface of AgNP to form PEG6K-HS-AgNP conjugates with a strong affinity due to thiol bonding to the AgNP surface. The formation of SH-PEG6K corona prevented PEG6K-HS-AgNP conjugates from aggregation under the acidic environment, but dissolution of core AgNPs occurred following a first-order reaction. The rate constant of Ag dissolution from PEG6K-HS-AgNP was independent of the starting surface packing density (σ0) of SH-PEG6K on AgNP, indicating the interactions of acid molecules was not interfered by the presence of SH-PEG6K corona. The surface adsorbate density of PEG6K-HS-AgNP decreased simultaneously following a first-order reaction, and the desorption rate constant was proportional to σ0. Our work presents the first quantitative study to illustrate the complex mechanism of PEGylated AgNP colloids that involves simultaneous aggregation and dissolution of core AgNPs in combination with adsorption and desorption of SH-PEG.

Surface PEGylation to silver nanoparticles: Kinetics of simultaneous surface dissolution and molecular desorption

254th National Meeting (2017)

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