Microstructure and elasticity of dilute gels of colloidal discoids

Kao, Peng-Kai; Solomon, Michael J.; Ganesan, M.

doi:10.1039/d1sm01605a

Cited by 15 publications

(20 citation statements)

References 87 publications

(168 reference statements)

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“…Far from φ c we find that the exponent of the yield strain is −0.55(−0.85) for the GO gels with (and without) salt. Using G ′ 0 ∼ φ 2.7 this results in β = 1.5(1.9) and d f = 2.1(1.9) which is similar to what has been found in other gels 28 . However, the addition of salt should increase the bond rigidity k 0 and thereby G ′ 0 , which is not what we observe.…”

Section: Soft Matter Accepted Manuscriptsupporting

confidence: 88%

“…The value of L c /L 0 for non-aqueous 3-layer graphene gel is consistent with this overall trend. This shows that the microstructure is not only affected by the particle interactions but also by the aspect ratio 28 . The overall decrease of L c /L 0 with α (L c /L 0 ∼ α −0.25 ) explains why φ c for all the gels shown only differ by a factor of ≈ 30 at most across 4 orders of magnitude in aspect ratio as…”

Section: Soft Matter Accepted Manuscriptmentioning

confidence: 84%

“…Note that a similar trend has been observed in graphene gels 8 and also for carbon nanotube suspensions. 7 This decrease in g y is also seen in gels with fractal microstructures, where theory 32,39 predicts that G 0 0 ¼ f ðk 0 =L 0 Þf ð1þbÞ=ð3Àd f Þ and g y p f (1Àb)/(3Àdf) assuming stiff particles. Here, b and d f are related to the fractal dimensions of the elastic backbone and the flocs, respectively, k 0 is the bond rigidity and f a prefactor.…”

mentioning

confidence: 83%

“…This shows that the microstructure is not only affected by the particle interactions but also by the aspect ratio. 32 The overall decrease of L c /L 0 with a (L c /L 0 B a À0.25 ) explains why f c for all the gels shown only differ by a factor of E30 at most across 4 orders of magnitude in aspect ratio as f c = (L c /L 0 ) À3 a À1 B a À0. 25 .…”

mentioning

confidence: 90%

“…Instead we introduce the area fraction a = m(f À f c ) x which denotes the fraction of the area of the free volume V f occupied by a single sheet that is in contact with neighboring sheets with an unknown exponent x which must be positive. Since f c { 1 for high aspect ratio particle suspensions, 22,32 the area fraction a should go to 1 in the theoretical limit of f = 1. Therefore the prefactor m is set to 1.…”

mentioning

confidence: 99%

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The elastic response of graphene oxide gels as a crumpling phenomenon

Barwich

Möbius

2022

Soft Matter

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Section: Soft Matter Accepted Manuscriptsupporting

confidence: 88%

Section: Soft Matter Accepted Manuscriptmentioning

confidence: 84%

mentioning

confidence: 83%

mentioning

confidence: 90%

mentioning

confidence: 99%

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The elastic response of graphene oxide gels as a crumpling phenomenon

Barwich

Möbius

2022

Soft Matter

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Microstructural and Rheological Transitions in Bacterial Biofilms

et al. 2023

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Biofilms are aggregated bacterial communities structured within an extracellular matrix (ECM). ECM controls biofilm architecture and confers mechanical resistance against shear forces. From a physical perspective, biofilms can be described as colloidal gels, where bacterial cells are analogous to colloidal particles distributed in the polymeric ECM. However, the influence of the ECM in altering the cellular packing fraction (ϕ) and the resulting viscoelastic behavior of biofilm remains unexplored. Using biofilms of Pantoea sp. (WT) and its mutant (ΔUDP), the correlation between biofilm structure and its viscoelastic response is investigated. Experiments show that the reduction of exopolysaccharide production in ΔUDP biofilms corresponds with a seven‐fold increase in ϕ, resulting in a colloidal glass‐like structure. Consequently, the rheological signatures become altered, with the WT behaving like a weak gel, whilst the ΔUDP displayed a glass‐like rheological signature. By co‐culturing the two strains, biofilm ϕ is modulated which allows us to explore the structural changes and capture a change in viscoelastic response from a weak to a strong gel, and to a colloidal glass‐like state. The results reveal the role of exopolysaccharide in mediating a structural transition in biofilms and demonstrate a correlation between biofilm structure and viscoelastic response.

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Mechanomorphological Guidance of Colloidal Gel Regulates Cell Morphogenesis

Lin

Linares

Ramírez

et al. 2023

Macromolecular Bioscience

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Microstructural morphology of the extracellular matrix guides the organization of cells in 3D. However, current biomaterials‐based matrices cannot provide distinct spatial cues through their microstructural morphology due to design constraints. To address this, colloidal gels are developed as 3D matrices with distinct microstructure by aggregating ionic polyurethane colloids via electrostatic screening. Due to the defined orientation of interconnected particles, positively charged colloids form extended strands resulting in a dense microstructure whereas negatively charged colloids form compact aggregates with localized large voids. Chondrogenesis of human mesenchymal stem cells (MSCs) and endothelial morphogenesis of human endothelial cells (ECs) are examined in these colloidal gels. MSCs show enhanced chondrogenic response in dense colloidal gel due to their spatial organization achieved by balancing the cell–cell and cell–matrix interactions compared to porous gels where cells are mainly clustered. ECs tend to form relatively elongated cellular networks in dense colloidal gel compared to porous gels. Additionally, the role of matrix stiffness and viscoelasticity in the morphogenesis of MSCs and ECs are analyzed with respect to microstructural morphology. Overall, these results demonstrate that colloidal gels can provide spatial cues through their microstructural morphology and in correlation with matrix mechanics for cell morphogenesis.

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Microstructure and elasticity of dilute gels of colloidal discoids

Abstract: The linear elasticity of dilute colloidal gels formed from discoidal particles is quantified as a function of aspect ratio and modeled by confocal microscopy characterization of their fractal cluster microstructure.

Cited by 15 publications

References 87 publications

The elastic response of graphene oxide gels as a crumpling phenomenon

The elastic response of graphene oxide gels as a crumpling phenomenon

Microstructural and Rheological Transitions in Bacterial Biofilms

Mechanomorphological Guidance of Colloidal Gel Regulates Cell Morphogenesis

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