Simulation Study of Aggregations of Monolayer-Protected Gold Nanoparticles in Solvents

Abstract

Coarse-grained (CG) molecular dynamics (MD) simulations were carried out to investigate the dynamics of 2.2 nm monolayer-protected gold nanoparticles (AuNPs) in solvents. The effects of ligand length, ligand terminal chemistry, solvents, and temperature were examined. It was found that AuNPs with unmodified alkanethiol ligands formed stable aggregates in water in the time scale of hundreds of nanoseconds (eight nanoparticles). In a particular case, the AuNPs aggregated into an infinite, one-dimensional chainlike assembly instead of clusters of aggregates. The aggregates of AuNPs with short ligand tails seemed to have an amorphous shape, whereas long-tailed AuNPs aggregated into a spherical cluster. The properties of ligand terminals had a dominant influence on the aggregation behavior of AuNPs. Increasing the polarity of the ligand terminals weakened the tendency of aggregation of AuNPs in water. For AuNPs imposed with charged terminals, they did not aggregate even with a high concentration of salt. However the aggregation behavior of AuNPs changed dramatically if the properties of solvent were altered. Temperature increase greatly accelerated the process of aggregation. The results suggest that the dynamics of monolayer-protected AuNPs can be controlled by their surface properties as well as the features of solvents.

Effect of Size and Surface Charge of Gold Nanoparticles on their Skin Permeability: A Molecular Dynamics Study

“…The CG parameters for CHOL and FFA were taken from our earlier work29. The CG parameters of thiol coated AuNPs were taken from previous simulation studies25262729. The simulations were carried out in NVT and NPT ensemble using the GROMACS MD package363738.…”

“…synthesized thiol coated colloidal AuNP of 3.75 ± 0.06 nm and based on their experiments, a new Coarse Grained (CG) model of AuNP was developed. JQ Lin et al 252627. developed a CG model for AuNPs and verified against experimental data.…”

“…Same research group investigated the dynamics of 2.2 nm monolayer protected AuNPs in solvents. The effects of ligand length, ligand terminal chemistry, solvents, and temperature were also studied27. Simonelli et al 28.…”

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“…J Lin et al [29][30][31] performed series of MD simulations to study the interaction of lipid bilayers with the alkyl thiol coated AuNP. They developed a coarse-grained model for gold nanoparticles and verified against experimental data.…”

High Strength, Molecularly Thin Nanoparticle Membranes

“…Both studies found crystalline NP structures with elastic moduli on the order of 1 GPa. At the liquid/vapor interface the aggregation of encoded NPs were studied by Lane and Grest [13] and Lin et al [14].…”