From Gold Nanoseeds to Nanorods: The Microscopic Origin of the Anisotropic Growth

Meena, Santosh Kumar; Sulpizi, Marialore

doi:10.1002/anie.201604594

Cited by 55 publications

(86 citation statements)

References 28 publications

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“…Furthermore, this input allows us to compare our results with previous MD studies. 30,31,[38][39][40]48 Sufficiency of time simulationFrom the root-mean-square deviation (RMSD) plot (Figure 3), one can verify that in the simulations for CTAC, CTAB H and CTAB R , the conformations stabilize at approximately 30 ns and remain stable for the rest of the simulation, which lasts 200 ns. However, the CTAB N model only achieves structural stability after 50 ns.…”

mentioning

confidence: 65%

“…Furthermore, this input allows us to compare our results with previous MD studies. 30,31,[38][39][40]48 Sufficiency of time simulation…”

Section: Resultsmentioning

confidence: 99%

“…4980 (see Figure 1 and Table 1). 30,31,[38][39][40] For the CTAB/Au system, the gold surface, with a (100) facet arrangement, was constructed using 1600 atoms, employing the protocol described by Meena and Sulpizi. 31 Two CTA + bilayers, having 90 fragments each, were added to the (100) gold surface ( Figure 2).…”

Section: System Setupmentioning

confidence: 99%

“…Finally, the LJAP employed for gold was that developed by Heinz et al 37 and was already used in previous studies. 31,38 All LJAPs adopted in this work are summarized in Table 1. For the micelle systems, the number of surfactant units used in the simulations was chosen based on the available experimental data 27,28,39,40 and previous theoretical studies.…”

mentioning

confidence: 99%

“…For the micelle systems, the number of surfactant units used in the simulations was chosen based on the available experimental data 27,28,39,40 and previous theoretical studies. 30,31,[38][39][40] Thus, the input configuration of the system was constructed, like in other former studies, as a bilayer of 90 surfactant units and a suitable number of water molecules for each system, ca. 4980 (see Figure 1 and Table 1).…”

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confidence: 99%

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Molecular Dynamics Simulations of Cetyltrimethylammonium Bromide (CTAB) Micelles and their Interactions with a Gold Surface in Aqueous Solution

Silva¹,

Dias²,

Hora³

et al. 2017

J. Braz. Chem. Soc.

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Surfactants are molecular structures with remarkable physicochemical properties and applications. Most of their characteristics are due to their ability to promote aggregation and interactions with different interfaces. The scarcity of theoretical studies dedicated to evaluating the forces involved in these interactions prompted us to propose other models capable of reproducing the experimental data in better ways. We carried out molecular dynamics (MD) simulations to obtain a model for cetyltrimethylammonium bromide (CTAB), selected from gromos54a7 force field parameters, that better describes most of its behaviors in aqueous solution (micellar structure, counterion dissociation, etc.) and its adsorption pattern on a gold surface. The parameters adopted for one of the models were able to mimic several characteristics suggested by experimental measurements of the CTAB micelles, as well their adsorption pattern on a gold surface. Indeed, this model was able to obtain quasi-spherical micelles, as well as a pattern of adjacent cylindrical micelles with alkyl chain interactions on a gold surface.Keywords: molecular dynamics, micelles, interface interaction, cetyltrimethylammonium bromide, gold IntroductionSurfactants are a class of compounds containing a polar group, charged or neutral, attached to a long hydrophobic tail.1,2 These are remarkably versatile compounds with a broad variety of important applications in the pharmaceutical, medical, and food industries and for nanomaterial synthesis.3,4 Above a certain temperature in solution (the Krafft temperature), surfactants tend to aggregate to minimize unfavorable interactions between the surfactants and the surrounding environment. 5 The minimum concentration required for surfactant aggregation is defined as the critical micellar concentration (CMC), and most of the characteristics of these aggregates are controlled by factors such as the solvent type, chemical structure of the surfactant, and solution conditions (e.g., concentration, temperature, presence of additives, and ionic strength). 6Variations of these factors yield aggregates with different morphologies such as spherical or ellipsoidal micelles, cylindrical or thread-like micelles, disk-like micelle, membranes and vesicles.7 These self-assembled structures have been characterized by a number of techniques, such as dynamic light scattering (DLS), 8 nuclear magnetic resonance (NMR), 9,10 fluorescence spectroscopy, 11 quasielastic neutron scattering (QENS), 12,13 small-angle X-ray scattering (SAXS), 14,15 and small-angle neutron scattering (SANS). 16,17 Computational simulations have also been employed to explore the structures and dynamical behaviors of micelles for different surfactants. 18Considering that no holes exist within a micelle, its radius is estimated as the maximum extension of a hydrocarbon chain and can be evaluated by using the following equation:where l max is the maximum length in nm and n C is the number of carbon atoms in the chain. 19 Indeed, under the previously mentioned conditions, ...

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mentioning

confidence: 65%

“…Furthermore, this input allows us to compare our results with previous MD studies. 30,31,[38][39][40]48 Sufficiency of time simulation…”

Section: Resultsmentioning

confidence: 99%

Section: System Setupmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Molecular Dynamics Simulations of Cetyltrimethylammonium Bromide (CTAB) Micelles and their Interactions with a Gold Surface in Aqueous Solution

Silva¹,

Dias²,

Hora³

et al. 2017

J. Braz. Chem. Soc.

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Direct Assembly of Vertically Oriented, Gold Nanorod Arrays

Zhang

Liu

Shahidan

et al. 2020

Adv Funct Materials

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Although many nanoscale materials such as quantum dots and metallic nanocrystals exhibit size dependent optical properties, it has been difficult to incorporate them into optical or electronic devices because there are currently no methods for precise, large‐scale deposition of single nanocrystals. Of particular interest is the need to control the orientation of single nanocrystals since the optical properties are usually strongly anisotropic. Here a method based on electrophoretic deposition (EPD) is reported to precisely assemble vertically oriented, single gold nanorods. It is demonstrated that the orientation of gold nanorods during deposition is controlled by the electric dipole moment induced along the rod by the electric field. Dissipative particle dynamics simulations indicate that the magnitude of this dipole moment is dominated by the polarizability of the solution phase electric double layer around the nanorod. The resulting vertical gold nanorod arrays exhibit reflected colors due to selective excitation of the transverse surface plasmon mode. The EPD method allows assembly of arrays with a density of over one million, visually resolvable, vertical nanorods per square millimeter.

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Synthesis of Uniform Gold Nanorods with Large Width to Realize Ultralow SERS Detection

Hong

et al. 2021

Chemistry A European J

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In this work, we successfully demonstrate high-yield synthesis of high-quality gold nanorods (Au NRs) with width ranging from 6.5 nm to 175 nm by introducing heptanol molecules as secondary templating agents during cetyltrimethylammonium bromide-templated, seeded growth method. The results show that an appropriate concentration of heptanol molecules not only alter the micellization behavior of CTAB in water, but also help silver ions impact the symmetry-breaking efficiency of additional AuÀ NP seeds in addition to enhancing the utilization of gold precursors.Moreover, the generality and versatility of the present strategy for synthesis of Au NRs with flexible controlled dimensions are further demonstrated by successful synthesis of Au NRs with the assistance of other fatty alcohols with properly long alkyl chains. Furthermore, when arrays of vertically aligned Au NRs with large width (AVAÀ Au 120 × 90 NRs) are used as SERS substrates, they can achieve the ultralow limit of detection for crystal violet (10 À 16 M) with good reliability and reproducibility, and the rapid detection and identification of residual harmful substances.

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From Gold Nanoseeds to Nanorods: The Microscopic Origin of the Anisotropic Growth

Cited by 55 publications

References 28 publications

Molecular Dynamics Simulations of Cetyltrimethylammonium Bromide (CTAB) Micelles and their Interactions with a Gold Surface in Aqueous Solution

Molecular Dynamics Simulations of Cetyltrimethylammonium Bromide (CTAB) Micelles and their Interactions with a Gold Surface in Aqueous Solution

Direct Assembly of Vertically Oriented, Gold Nanorod Arrays

Synthesis of Uniform Gold Nanorods with Large Width to Realize Ultralow SERS Detection

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