Hydrophobic Interactions Modulate Self-Assembly of Nanoparticles

Sánchez‐Iglesias, Ana; Grzelczak, Marek; Altantzis, Thomas; Goris, Bart; Pérez‐Juste, Jorge; Tendeloo, Gustaaf Van; Donaldson, Stephen H.; Chmelka, Bradley F.; Israelachvili, Jacob N.; Liz‐Marzán, Luis M.

doi:10.1021/nn3047605

Cited by 349 publications

(367 citation statements)

References 42 publications

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“…Although a variety of gold nanoparticle (Au NP) supraspheres have been prepared [14][15][16][17] , the hydrophobically driven formation of analogous assemblies in pure water remains elusive [18][19][20][21] . The main obstacle is that precipitation rapidly results from a lack of control over the aggregation processes 19 .…”

Section: Hydrophobically Driven Assembly In Watermentioning

confidence: 99%

“…As a result, the hydrophilic polyoxometalate monolayer directs the selective placement of thiolate ligands into discrete hydrophobic domains on the Au NPs 26,27 , while intact domains of 1 remain in place to continuously impart solubility in water. As more alkanethiol is added, the 1 domains are gradually displaced, leading to the controlled hydrophobic assembly of supraspherical clusters 18 .…”

Section: Hydrophobically Driven Assembly In Watermentioning

confidence: 99%

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Host–guest chemistry with water-soluble gold nanoparticle supraspheres

et al. 2016

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The uptake of molecular guests, a hallmark of the supramolecular chemistry of cages and containers, has yet to be documented for soluble assemblies of metal nanoparticles. Here we demonstrate that gold nanoparticle-based supraspheres serve as a host for the hydrophobic uptake, transport and subsequent release of over two million organic guests, exceeding by five orders of magnitude the capacities of individual supramolecular cages or containers and rivalling those of zeolites and metal-organic frameworks on a mass-per-volume basis. The supraspheres are prepared in water by adding hexanethiol to polyoxometalate-protected 4 nm gold nanoparticles. Each 200 nm assembly contains hydrophobic cavities between the estimated 27,400 gold building blocks that are connected to one another by nanometre-sized pores. This gives a percolated network that effectively absorbs large numbers of molecules from water, including 600,000, 2,100,000 and 2,600,000 molecules (35, 190 and 234 g l ) of para-dichorobenzene, bisphenol A and trinitrotoluene, respectively.H ost-guest phenomena that involve the uptake of gases and small molecules are associated with the supramolecular chemistry of soluble capsules, cages and containers [1][2][3][4][5] or, alternatively, with heterogeneous reactions of porous solid-state materials such as zeolites 6 and metal-organic frameworks 7 . Only now, however, are organized assemblies of metal nanoparticles beginning to serve in a similar capacity as hosts for molecular guests. In organic solvents, for example, light-induced dipoledipole interactions between gold nanoparticles with azobenzenefunctionalized thiolate ligands were recently used to entrap and catalyse the reactions of polar and alkylaromatic substrates 8 . By design, substrates were entrapped during nanoparticle aggregation to overcome the poor uptake and diffusion of molecular guests into colloidal nanocrystal assemblies. However, the uptake of molecular guests, a trait of supramolecular and solid-state chemistry, has so far not been achieved for colloidal nanoparticle assemblies.For that to occur, a thermodynamically favourable driving force must be combined with a porous structure whose interior architecture features host cavities, along with pathways for the effective diffusion of molecular guests from the exterior (bulk solution) to host domains deeply buried in the assembly's interior. If this were achieved, colloidal metal-nanoparticle assemblies could emerge as a new class of functional nano-engineered structures that are uniquely positioned between supramolecular containers and porous solid-state materials.We report a new class of functional assemblies, wherein the hydrophobic effect 9,10 drives the spontaneous uptake of alkyl and alkylaromatic guests 11 by porous 200 nm diameter supraspheres whose host capacities are orders of magnitude larger than those of individual cages or containers. On a mass-per-volume basis, the level of uptake rivals those of zeolites and metal-organic frameworks, which, for methane at elevated pressures, r...

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Section: Hydrophobically Driven Assembly In Watermentioning

confidence: 99%

Section: Hydrophobically Driven Assembly In Watermentioning

confidence: 99%

Host–guest chemistry with water-soluble gold nanoparticle supraspheres

et al. 2016

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“…The findings presented here show that by varying the ion concentration and temperature, one can finetune the steric interaction. Although it should be noted that the hydrophobic interaction between the surface grafted polymers may also play a role, 34 increasing the attraction between the nanoparticles at smaller separations, thus it can contribute to the aggregation of the NPs. Suspensions were allowed to assemble for 600 seconds, and the clustering process was quenched by dipping the sample into ice cold water, after which ultrasonication was applied for 3 or for 5 minutes for different samples.…”

Section: Please Do Not Adjust Marginsmentioning

confidence: 99%

Aggregation kinetics and cluster structure of amino-PEG covered gold nanoparticles

et al. 2016

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In this study controlled clustering kinetics is demonstrated for PEG grafted gold nanoparticles, in response to applied environmental stimuli; the temperature and ionic strength of the medium. It is also found that the rate of assembly determines the structure of the prepared clusters. After the system is brought out of equilibrium, time-dependent extinction and dynamic light scattering data are used to follow the evolution of nanoparticle cluster formation in real time. The results show that the rate of assembly increases with increasing ionic strength or temperature of the medium. As a result the nanoparticle cluster size scales with ionic strength and temperature, over a cluster size range from a few particle sizes up to the micron-scale. It is found that, even at the lowest ionic strength, the electric double layer repulsion is eliminated; hence the observed differences in kinetics and in cluster structure arise from modulation of the repulsive steric interactions between nanoparticles. The approach should be extendable to suspensions of other nanoparticle types, where the nanoparticle stability is determined by surface-grafted responsive macromolecules.

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“…4 (a)) [18] . It has only one chemical composition and a relatively more complex structure than the second sample.…”

Section: Methodsmentioning

confidence: 99%

Automatic correction of nonlinear damping effects in HAADF–STEM tomography for nanomaterials of discrete compositions

et al. 2018

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a b s t r a c t HAADF-STEM tomography is a common technique for characterizing the three-dimensional morphology of nanomaterials. In conventional tomographic reconstruction algorithms, the image intensity is assumed to be a linear projection of a physical property of the specimen. However, this assumption of linearity is not completely valid due to the nonlinear damping of signal intensities. The nonlinear damping effects increase w.r.t the specimen thickness and lead to so-called "cupping artifacts", due to a mismatch with the linear model used in the reconstruction algorithm. Moreover, nonlinear damping effects can strongly limit the applicability of advanced reconstruction approaches such as Total Variation Minimization and discrete tomography.In this paper, we propose an algorithm for automatically correcting the nonlinear effects and the subsequent cupping artifacts. It is applicable to samples in which chemical compositions can be segmented based on image gray levels. The correction is realized by iteratively estimating the nonlinear relationship between projection intensity and sample thickness, based on which the projections are linearized. The correction and reconstruction algorithms are tested on simulated and experimental data.

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Hydrophobic Interactions Modulate Self-Assembly of Nanoparticles

Cited by 349 publications

References 42 publications

Host–guest chemistry with water-soluble gold nanoparticle supraspheres

Host–guest chemistry with water-soluble gold nanoparticle supraspheres

Aggregation kinetics and cluster structure of amino-PEG covered gold nanoparticles

Automatic correction of nonlinear damping effects in HAADF–STEM tomography for nanomaterials of discrete compositions

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