Generation of Fermat’s spiral patterns by solutal Marangoni-driven coiling in an aqueous two-phase system

Xiao, Yang; Ribe, Neil M.; Zhang, Yage; Pan, Yi; Cao, Yang; Shum, Ho Cheung

doi:10.1038/s41467-022-34368-5

Cited by 8 publications

(5 citation statements)

References 31 publications

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“…Parts of this process may be attributed to the formation of an emulsion due to the residual small amount of water in the nanoparticles during the phase transition 35 . Then, due to toluene evaporation, these isolated rings gradually aggregate through the Marangoni effect 36 (Fig. 1b 1, Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

Superlattice assembly strategy of small noble metal nanoparticles for surface-enhanced Raman scattering

Yao,

Yan,

Dong

et al. 2024

Commun Mater

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The self-assembly of noble metal nanoparticles into periodic structures has been a theme of great interest for surface-enhanced Raman scattering (SERS) and use in functional devices. However, small nanoparticle self-assembly faces numerous challenges in tunability, referring to controlling their structural properties like structure, gaps, and arrangement. These issues highlight the need for further research and development to enhance the tunability and stability of self-assembled small nanoparticles. Here, we report a general centimeter-scale superlattice assembly strategy for noble metal nanoparticles less than 15 nm in size. Not only is this monolayer superlattice assembly generally applicable to different kinds and sizes of noble metal nanoparticles, but also, the crystal plane spacing can also be quickly and conveniently controlled by changing the ethanol concentration. SERS results reveal that optimized superlattice membranes of noble metal nanoparticles possess high detection sensitivity and ordered hot spots. Therefore, our strategy offers prospects for high-performance SERS substrates based on small noble metal nanoparticle superlattices.

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Section: Resultsmentioning

confidence: 99%

Superlattice assembly strategy of small noble metal nanoparticles for surface-enhanced Raman scattering

Yao,

Yan,

Dong

et al. 2024

Commun Mater

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“…This balance between short-range attraction and long-range electrostatic repulsion provides a stable mechanism for preventing coagulation . In metastable three-phase systems, Marangoni convection induces clockwise or counterclockwise Fermat’s spiral that drives the transfer of more and more nanoclusters to the W/A interface . Moreover, the Marangoni force overcomes the electrostatic repulsion between nanoclusters so that the nanoparticles self-assemble into a dense multilayer film at the center of the W/A interface (spiral center) to the whole interface (Figure b-iv).…”

Section: Resultsmentioning

confidence: 99%

“…Marangoni-driven spreading on liquid surfaces or Marangoni convection within a liquid is a powerful method for fast selfdriving assembly of nanoparticles. 13,14 The Marangoni effect can be defined as (1) The above equation indicates that the Marangoni effect mainly comes from the surface tension gradients caused by the liquid temperature and composition , 15 where the surface tension gradient will pull the liquid from the low surface tension region to the high surface tension region until the gradient is eliminated. In other words, by changing the temperature and composition of the liquid, the surface tension gradient can occur, thus producing a Marangoni effect.…”

Section: Introductionmentioning

confidence: 99%

“…The above equation indicates that the Marangoni effect mainly comes from the surface tension gradients caused by the liquid temperature true( ∂ γ ∂ T true) and composition true( ∂ γ ∂ c true) , where the surface tension gradient will pull the liquid from the low surface tension region to the high surface tension region until the gradient is eliminated. In other words, by changing the temperature and composition of the liquid, the surface tension gradient can occur, thus producing a Marangoni effect.…”

Section: Introductionmentioning

confidence: 99%

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Three-Phase Catassembly of 10 nm Au Nanoparticles for Sensitive and Stable Surface-Enhanced Raman Scattering Detection

Xie,

Li,

Wang

et al. 2023

Anal. Chem.

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Interfacial self-assembly with the advantage of providing large-area, high-density plasmonic hot spots is conducive to achieving high sensitivity and stable surface-enhanced Raman scattering (SERS) sensing. However, rapid and simple assembly of highly repeatable large-scale multilayers with small nanoparticles remains a challenge. Here, we proposed a catassembly approach, where the “catassembly” means the increase in the rate and control of nanoparticle assembly dynamics. The catassembly approach was dropping heated Au sols onto oil chloroform (CHCl3), which triggers a rapid assembly of plasmonic multilayers within 15 s at the oil–water–air (O/W/A) interface. A mixture of heated sol and CHCl3 constructs a continuous liquid–air interfacial tension gradient; thus, the plasmonic multilayer film can form rapidly without adding functional ligands. Also, the dynamic assembly process of the three-phase catassembly ranging from cluster to interfacial film formation was observed through experimental characterization and COMSOL simulation. Importantly, the plasmonic multilayers of 10 nm Au NPs for SERS sensing demonstrated high sensitivity with the 1 nM level for crystal violet molecules and excellent stability with an RSD of about 10.0%, which is comparable to the detection level of 50 nm Au NPs with layer-by-layer assembly, as well as breaking the traditional and intrinsic understanding of small particles of plasmon properties. These plasmonic multilayers of 10 nm Au NPs through the three-phase catassembly method illustrate high SERS sensitivity and stability, paving the way for small-nanoparticle SERS sensing applications.

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“…44 In addition, combining this system with Marangoni convections driven by chemical reactions, 45−47 concentration gradients of surfactants, 48,49 and local heating, 50,51 more complex and longterm movements of motile droplets will be expected. Incorporation of various biopolymers should result in shearinduced segregation 52 and also the alignments of stiff polymers such as collagen fibrils by the flow. 53 We expect that our findings about the active flow-induced segregation of DNA inside the droplets will contribute to the comprehension of selforganization mechanisms through phase separation under convection such as LLPS in cells.…”

Section: Discussionmentioning

confidence: 99%

Marangoni Droplets of Dextran in PEG Solution and Its Motile Change Due to Coil–Globule Transition of Coexisting DNA

Furuki,

Sakuta,

Yanagisawa

et al. 2024

ACS Appl. Mater. Interfaces

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Motile droplets using Marangoni convection are attracting attention for their potential as cell-mimicking small robots. However, the motion of droplets relative to the internal and external environments that generate Marangoni convection has not been quantitatively described. In this study, we used an aqueous two-phase system [poly(ethylene glycol) (PEG) and dextran] in an elongated chamber to generate motile dextran droplets in a constant PEG concentration gradient. We demonstrated that dextran droplets move by Marangoni convection, resulting from the PEG concentration gradient and the active transport of PEG and dextran into and out of the motile dextran droplet. Furthermore, by spontaneously incorporating long DNA into the dextran droplets, we achieved cell-like motility changes controlled by coexisting environment-sensing molecules. The DNA changes its position within the droplet and motile speed in response to external conditions. In the presence of Mg 2+ , the coil−globule transition of DNA inside the droplet accelerates the motile speed due to the decrease in the droplet's dynamic viscosity. Globule DNA condenses at the rear part of the droplet along the convection, while coil DNA moves away from the droplet's central axis, separating the dipole convections. These results provide a blueprint for designing autonomous small robots using phase-separated droplets, which change the mobility and molecular distribution within the droplet in reaction with the environment. It will also open unexplored areas of self-assembly mechanisms through phase separation under convections, such as intracellular phase separation.

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Generation of Fermat’s spiral patterns by solutal Marangoni-driven coiling in an aqueous two-phase system

Cited by 8 publications

References 31 publications

Superlattice assembly strategy of small noble metal nanoparticles for surface-enhanced Raman scattering

Superlattice assembly strategy of small noble metal nanoparticles for surface-enhanced Raman scattering

Three-Phase Catassembly of 10 nm Au Nanoparticles for Sensitive and Stable Surface-Enhanced Raman Scattering Detection

Marangoni Droplets of Dextran in PEG Solution and Its Motile Change Due to Coil–Globule Transition of Coexisting DNA

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