Depletion-Driven Assembly of Polymer-Coated Nanocrystals

Green, Allison; Kadulkar, Sanket; Sherman, Zachary M.; FitzSimons, Thomas; Ofosu, Charles K.; Yan, Jiajun; Zhao, David; Ilavský, Ján; Rosales, Adrianne M.; Helms, Brett A.; Ganesan, Venkat; Truskett, Thomas M.; Milliron, Delia J.

doi:10.1021/acs.jpcc.2c06279

Cited by 3 publications

(2 citation statements)

References 121 publications

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“…DLS measurements for the size and solvent series revealed consistent thermodynamic and hydrodynamic diameters, further indicating hard-sphere-like behavior. A similar correspondence between the thermodynamic and hydrodynamic diameters was very recently observed for tin-doped indium oxide nanocrystals wrapped with three different copolymers dispersed in acetonitrile whose pairwise interactions were also characterized by a purely repulsive potential of mean force . The ability to systematically vary the size of NC building blocks and disperse them in a range of solvents while maintaining hard-particle-like interactions is foundational for design of assembly.…”

supporting

confidence: 73%

Effective Hard-Sphere Repulsions between Oleate-Capped Colloidal Metal Oxide Nanocrystals

Ofosu

Kang

Truskett

et al. 2022

J. Phys. Chem. Lett.

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Nanocrystal interactions in solvent influence colloidal stability and dictate selfassembly outcomes. Small-angle X-ray scattering is used to study how dilute oleate-capped In 2 O 3 nanocrystals with 7−19 nm core diameters interact when dispersed in a series of nonpolar solvents. Osmotic second virial coefficient analysis finds toluene-dispersed nanocrystals in this size range interact like effective hard spheres with diameters comprising the inorganic core and a ligand−solvent corona with a core-size independent thickness. Hardsphere-like structure factors are similarly observed for nanocrystals with a 9.7 nm core diameter dispersed in all the solvents investigated. Nanocrystal hydrodynamic diameters from dynamic light scattering measurements correlate with thermodynamic diameters obtained from the osmotic second virial coefficient analysis for all samples. The ability to prepare nanoscale building blocks of different sizes, and dispersed in a variety of solvents, with effective hardsphere repulsions provides a foundation for assembly, where secondary linking or depletant molecules can be deliberately added to customize interactions to form superstructures such as gel networks or superlattices.

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supporting

confidence: 73%

Effective Hard-Sphere Repulsions between Oleate-Capped Colloidal Metal Oxide Nanocrystals

Ofosu

Kang

Truskett

et al. 2022

J. Phys. Chem. Lett.

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“…The use of depletants is a common strategy to induce the assembly of colloidal crystals. For instance, polymers like polyethylene glycol (PEG) 46 or excess ligands 47 are often added to a nanoparticle dispersion to produce assemblies. Depleting species act by creating an excluded volume to the nanocrystal diffusion, which in turn promotes the formation of dense or ordered phases.…”

Section: Mechanism Of the Supercrystal Formationmentioning

confidence: 99%

Direct Synthesis of CuPd Icosahedra Supercrystals studied by in situ X-ray Scattering

Derelli,

Frank,

Grote

et al. 2023

Preprint

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Nanocrystal self-assembly into supercrystals provides a versatile platform for creating novel materials and devices with tailored properties. While common self-assembly strategies imply the use of purified nanoparticles after synthesis, conversion of chemical precursors directly into nanocrystals and then supercrystals in simple procedures has been rarely reported. Here we study the nucleation and growth of CuPd icosahedra and their consecutive assembly into extended closed-packed face-centered cubic (fcc) supercrystals. To this end, we simultaneously and in situ measure X-ray total scattering with pair-distribution function analysis (TS-PDF) and small-angle X-ray scattering (SAXS). We find that the supercrystals formation is preceded by an intermediate dense phase of nanocrystals displaying short-range order (SRO). We further show that the organization of oleic acid/oleylamine surfactants into lamellar structures likely drives the emergence of the SRO phase and later of the supercrystals by creating an excluded volume to particle diffusion. The supercrystal formation as well as their disassembly are triggered by temperature. Our study demonstrates that depletion effects can be crucial in the direct synthesis of supercrystals. We also provide a general approach to investigate novel preparation routes of supercrystals in situ and across several length scales via X-ray scattering.

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Morphological control of bundled actin networks subject to fixed-mass depletion

Clarke,

Melcher,

Crowell

et al. 2024

The Journal of Chemical Physics

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Depletion interactions are thought to significantly contribute to the organization of intracellular structures in the crowded cytosol. The strength of depletion interactions depends on physical parameters such as the depletant number density and the depletant size ratio. Cells are known to dynamically regulate these two parameters by varying the copy number of proteins of a wide distribution of sizes. However, mammalian cells are also known to keep the total protein mass density remarkably constant, to within 0.5% throughout the cell cycle. We thus ask how the strength of depletion interactions varies when the total depletant mass is held fixed, a.k.a. fixed-mass depletion. We answer this question via scaling arguments, as well as by studying depletion effects on networks of reconstituted semiflexible actin in silico and in vitro. We examine the maximum strength of the depletion interaction potential U∗ as a function of q, the size ratio between the depletant and the matter being depleted. We uncover a scaling relation U∗ ∼ qζ for two cases: fixed volume fraction φ and fixed mass density ρ. For fixed volume fraction, we report ζ < 0. For the fixed mass density case, we report ζ > 0, which suggests that the depletion interaction strength increases as the depletant size ratio is increased. To test this prediction, we prepared our filament networks at fixed mass concentrations with varying sizes of the depletant molecule poly(ethylene glycol) (PEG). We characterize the depletion interaction strength in our simulations via the mesh size. In experiments, we observe two distinct actin network morphologies, which we call weakly bundled and strongly bundled. We identify a mass concentration where different PEG depletant sizes lead to weakly bundled or strongly bundled morphologies. For these conditions, we find that the mesh size and intra-bundle spacing between filaments across the different morphologies do not show significant differences, while the dynamic light scattering relaxation time and storage modulus between the two states do show significant differences. Our results demonstrate the ability to tune actin network morphology and mechanics by controlling depletant size and give insights into depletion interaction mechanisms under the fixed-depletant-mass constraint relevant to living cells.

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Depletion-Driven Assembly of Polymer-Coated Nanocrystals

Cited by 3 publications

References 121 publications

Effective Hard-Sphere Repulsions between Oleate-Capped Colloidal Metal Oxide Nanocrystals

Effective Hard-Sphere Repulsions between Oleate-Capped Colloidal Metal Oxide Nanocrystals

Direct Synthesis of CuPd Icosahedra Supercrystals studied by in situ X-ray Scattering

Morphological control of bundled actin networks subject to fixed-mass depletion

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