Gold Nanoparticle/Polymer Interfaces: All Atom Structures from Molecular Dynamics Simulations

Milano, Giuseppe; Santangelo, Giuseppe; Ragone, Francesco; Cavallo, Luigi; Matteo, Andrea Di

doi:10.1021/jp201374h

Cited by 60 publications

(60 citation statements)

References 47 publications

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“…This feature of the Au−S interface, which exists also for self-assembled monolayers on bulk Au, has not been incorporated previously for AuNP simulations with classical force fields. 28,29,31,41 with the water density at the given temperature. The overall number of atoms in the simulated systems was around 33 000.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Atomistic Simulations of Functional Au₁₄₄(SR)₆₀ Gold Nanoparticles in Aqueous Environment

et al. 2012

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Charged monolayer-protected gold nanoparticles (AuNPs) have been studied in aqueous solution by performing atomistic molecular dynamics simulations at physiological temperature (310 K). Particular attention has been paid to electrostatic properties that modulate the formation of a complex comprised of the nanoparticle together with surrounding ions and water. We focus on Au 144 nanoparticles that comprise a nearly spherical Au core (diameter ∼2 nm), a passivating Au−S interface, and functionalized alkanethiol chains. Cationic and anionic AuNPs have been modeled with amine and carboxyl terminal groups and Cl − /Na + counterions, respectively. The radial distribution functions show that the side chains and terminal groups show significant flexibility. The orientation of water is distinct in the first solvation shell, and AuNPs cause a long-range effect in the solvent structure. The radial electrostatic potential displays a minimum for AuNP − at 1.9 nm from the center of the nanoparticle, marking a preferable location for Na + , while the AuNP + potential (affecting the distribution of Cl − ) rises almost monotonically with a local maximum. Comparison to Debye−Huckel theory shows very good agreement for radial ion distribution, as expected, with a Debye screening length of about 0.2−0.3 nm. Considerations of zeta potential predict that both anionic and cationic AuNPs avoid coagulation. The results highlight the importance of long-range electrostatic interactions in determining nanoparticle properties in aqueous solutions. They suggest that electrostatics is one of the central factors in complexation of AuNPs with other nanomaterials and biological systems, and that effects of electrostatics as water-mediated interactions are relatively long-ranged, which likely plays a role in, e.g., the interplay between nanoparticles and lipid membranes that surround cells. ■ INTRODUCTIONNanoparticles (NPs, size range 1−100 nm) have many interesting properties, as they bridge the gap between bulk materials and atomic or molecular structures.1,2 Typically, the physical properties of bulk materials do not depend on the size of the sample, while at the nanoscale size-dependent properties are frequently encountered. Two contributing factors for the size dependence are (a) number of surface atoms whose percentage reduces as the NP size increases toward the bulk limit and (b) quantum confinement effects at the smallest length scales (<10 nm) where the electronic structure plays a significant role in determining the composition, stability, structure, and function of NPs. 3,4 Nanoparticles often display fascinating optical properties because of quantum effects, and, e.g., gold nanoparticles (AuNPs) appear from yellow to deep red and black in solution depending on their size. 5 In photovoltaic cells, absorption of solar radiation is much higher for semiconductor materials comprised of NPs than for continuous sheets of thin films (e.g., CdTe, ZnO).6 For phase-change materials used in optical data storage and nonvolatile computer ...

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Section: ■ Materials and Methodsmentioning

confidence: 99%

Atomistic Simulations of Functional Au₁₄₄(SR)₆₀ Gold Nanoparticles in Aqueous Environment

et al. 2012

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“…[41][42] More recently, reverse mapping procedures have also been applied to polystyrene 44,68 and to study gold nanoparticles polymer interfaces. 68 The extension of reverse mapping to nonequilibrium situations, such as the determination of the rheology, has been recently demonstrated for atactic polystyrene under steady shear flow. 69 In the following the proposed strategy for the reverse mapping of TX-100 is explained in detail.…”

Section: Reverse Mappingmentioning

confidence: 99%

Self-Assembly of Triton X-100 in Water Solutions: A Multiscale Simulation Study Linking Mesoscale to Atomistic Models

Kawakatsu

Rosano

Celino

et al. 2015

J. Chem. Theory Comput.

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A multiscale scheme is proposed and validated for Triton X-100 (TX-100), which is a detergent widely employed in biology. The hybrid particle field formulation of the model allows simulations of large-scale systems. The coarse-grained (CG) model, accurately validated in a wide range of concentrations, shows a critical micelle concentration, shape transition in isotropic micellar phase, and appearance of hexagonal ordered phase in the experimental ranges reported in the literature. The fine resolution of the proposed CG model allows one to obtain, by a suitable reverse mapping procedure, atomistic models of micellar assemblies and of the hexagonal phase. In particular, atomistic models of the micelles give structures in good agreement with experimental pair distance distribution functions and hydrodynamic measurements. The picture emerging by detailed analysis of simulated systems is quite complex. Polydisperse mixtures of spherical-, oblate-, and prolate-shaped aggregates have been found. The shape and the micelle behavior are mainly dictated by the aggregation number (Nagg). Micelles with low Nagg values (∼40) are spherical, while those with high Nagg values (∼140 or larger) are characterized by prolate ellipsoidal shapes. For intermediate Nagg values (∼70), fluxional micelles alternating between oblate and prolate shapes are found. The proposed model opens the way to investigations of several mechanisms involving TX-100 assembly in protein and membrane biophysics.

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“…4 A molecular dynamics study of gold nanoparticles interacting with a polystyrene interface showed that the presence of surfactant-stabilizer can cause significant disordering of the polystyrene chains compared to an uncoated particle, with performance implications for memorystorage devices. 5 It is therefore important to be able to control the shape and core accessibility of a nanoparticle via suitable choice of surfactant stabilizer and solvent conditions. 6,7 For example, Wieneke et al…”

Section: Introductionmentioning

confidence: 99%

Self-Assembly of Calcium Carbonate Nanoparticles in Water and Hydrophobic Solvents

et al. 2014

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The self-assembly of Ca 2+ and CO 2− 3 ions into nanoparticles in water and hydrophobic solvents is investigated using Molecular Dynamics (MD) computer simulation. A new three-stage particle assembly procedure is used which relaxes the structure of the nanoparticle towards a lower energy state. In hydrophobic solvent the bare particle is essentially spherical whereas in water it is ellipsoidally shaped. With surfactant stabilizer the nanoparticles typically exhibit non-spherical cores in model hydrophobic solvents. Binary surfactant systems exhibit synergistic effects were for example a salicylate-sulfonate combination forms a cage which promotes a compact core. Synergistic effects on the shape of the particle were also observed in a hydrophobic solvent for surfactant-stabilized systems with trace water as a third component.The simulations show that rather than being a rigid structure the carbonate core shape and stabilizing shell coverage is sensitive to solvent, surfactant and small polar molecules which act as co-surfactants.

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Gold Nanoparticle/Polymer Interfaces: All Atom Structures from Molecular Dynamics Simulations

Cited by 60 publications

References 47 publications

Atomistic Simulations of Functional Au₁₄₄(SR)₆₀ Gold Nanoparticles in Aqueous Environment

Atomistic Simulations of Functional Au₁₄₄(SR)₆₀ Gold Nanoparticles in Aqueous Environment

Self-Assembly of Triton X-100 in Water Solutions: A Multiscale Simulation Study Linking Mesoscale to Atomistic Models

Self-Assembly of Calcium Carbonate Nanoparticles in Water and Hydrophobic Solvents

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Gold Nanoparticle/Polymer Interfaces: All Atom Structures from Molecular Dynamics Simulations

Cited by 60 publications

References 47 publications

Atomistic Simulations of Functional Au144(SR)60 Gold Nanoparticles in Aqueous Environment

Atomistic Simulations of Functional Au144(SR)60 Gold Nanoparticles in Aqueous Environment

Self-Assembly of Triton X-100 in Water Solutions: A Multiscale Simulation Study Linking Mesoscale to Atomistic Models

Self-Assembly of Calcium Carbonate Nanoparticles in Water and Hydrophobic Solvents

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Atomistic Simulations of Functional Au₁₄₄(SR)₆₀ Gold Nanoparticles in Aqueous Environment

Atomistic Simulations of Functional Au₁₄₄(SR)₆₀ Gold Nanoparticles in Aqueous Environment