Colloids and Interfaces

15 pages, 1878 KiB

Open AccessArticle

Distribution of Red Blood Cells Deformability: Study on Density-Separated Cell Subpopulations

by Gregory Barshtein, Dan Arbell, Alexander Gural and Leonid Livshits

Colloids Interfaces 2024, 8(4), 47; https://doi.org/10.3390/colloids8040047 - 19 Aug 2024

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Aging-related processes lead to significant metabolic and structural changes in red blood cells (RBCs) and, as a result, to heterogeneity in cell populations. Using the Percoll linear density gradient, separating the RBC population and obtaining fractions enriched with cells of different ages is [...] Read more.

Aging-related processes lead to significant metabolic and structural changes in red blood cells (RBCs) and, as a result, to heterogeneity in cell populations. Using the Percoll linear density gradient, separating the RBC population and obtaining fractions enriched with cells of different ages is possible. Previously, cells from the “light” fraction were characterized by increased deformability. However, the distribution of RBC deformability in subpopulations possessing a different density has not been studied. In this study, we measured the deformability of RBCs from cell fractions characterized by different densities. RBC deformability was determined using a computerized cell flow-properties analyzer, which provides the deformability distribution in a population of 10,000–15,000 cells. Our results demonstrate a strong correlation between the cytosol hemoglobin concentration and the cell deformation indexes. In addition, we show that the “lightest” fraction of RBCs contains the lowest number of deformable and the highest number of highly deformable cells. In contrast, the “dense” fraction is enriched with undeformable RBCs, with a minimal presence of highly deformable cells. In summary, we have shown that RBC fractions depleted or enriched with undeformable cells can be obtained by using a density gradient. However, these fractions are not homogeneous in their deformability properties. Full article

(This article belongs to the Special Issue Rheology of Complex Fluids and Interfaces)

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14 pages, 3763 KiB

Open AccessArticle

Extraction and Surface Activity of Australian Native Plant Extracts: Alphitonia excelsa

by Damien A. Sebben, Susan J. Semple, Mark R. Condina, Brooke A. Dilmetz, Peter Hoffmann, David J. Claudie, Marta Krasowska and David A. Beattie

Colloids Interfaces 2024, 8(4), 46; https://doi.org/10.3390/colloids8040046 - 19 Aug 2024

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Abstract

Saponin surfactants extracted from plants have significant potential applications in many industries. The interfacial properties of extracts of Alphitonia excelsa, a native Australian plant rich in saponins, have been characterised to assess their suitability as dual-purpose foaming and antibacterial additives. Two sources [...] Read more.

Saponin surfactants extracted from plants have significant potential applications in many industries. The interfacial properties of extracts of Alphitonia excelsa, a native Australian plant rich in saponins, have been characterised to assess their suitability as dual-purpose foaming and antibacterial additives. Two sources of the plant (Adelaide Botanic Gardens and homelands of Chuulangun Aboriginal Corporation) were investigated to look for alteration of properties as a result of differences in cultivation and geographic location. Two methods of saponin extraction (water and water/ethanol mixtures) were investigated to determine differences in extraction efficiency and performance. Distinct differences were observed between the traditional analytical analysis (for saponin content) of the extracts based on source and extraction method; however, these differences were not as stark when considering the effect of the extracts on air–water interfacial tension and dilatational rheology, with extraction method proving to be the single biggest factor in extract efficacy. The data obtained point toward the presence of an altered array of surface-active species (different relative amounts of particular saponins in the water/ethanol extracted material) as a function of the extraction method. All extracts presented some antibacterial effect, albeit modest. This work highlights that the extraction method needs to be carefully considered and tailored for a given application. Full article

(This article belongs to the Special Issue Surfactants and Interfaces)

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12 pages, 2944 KiB

Open AccessArticle

Fluctuations in Humidity Influence the Structure Formation and Swelling of Casein Microparticles

by Calvin Hohn and Ronald Gebhardt

Colloids Interfaces 2024, 8(4), 45; https://doi.org/10.3390/colloids8040045 - 14 Aug 2024

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Abstract

Caseins are a sustainable alternative to non-biodegradable materials for the production of functional microparticles. These show a characteristic swelling behavior when they are prepared from micellar casein under gentle conditions using depletion flocculation and subsequent film drying. The typical two-step swelling process is [...] Read more.

Caseins are a sustainable alternative to non-biodegradable materials for the production of functional microparticles. These show a characteristic swelling behavior when they are prepared from micellar casein under gentle conditions using depletion flocculation and subsequent film drying. The typical two-step swelling process is a result of the internal particulate network structure, which is surrounded by water channels. The seasonal and daily fluctuations in humidity during the 16 h film drying process influence the structure formation and swelling kinetics, which we analyze using system dynamics analysis. Microparticles with better and more uniform swelling properties can be produced using a drying apparatus with an integrated humidifier and ventilation system. At higher humidity levels, the casein micelles are less compressed during film drying, which facilitates the initial swelling of the microparticles. Furthermore, the more stable drying conditions in the drying apparatus result in a more homogeneous compaction of the film, which causes similar swelling rates for different microparticles. Full article

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10 pages, 1377 KiB

Open AccessCommunication

An Adoption of the Fractional Maxwell Model for Characterizing the Interfacial Dilational Viscoelasticity of Complex Surfactant Systems

by Giuseppe Loglio, Agnieszka Czakaj, Ewelina Jarek, Volodymyr I. Kovalchuk, Marcel Krzan, Libero Liggieri, Reinhard Miller and Piotr Warszynski

Colloids Interfaces 2024, 8(4), 44; https://doi.org/10.3390/colloids8040044 - 30 Jul 2024

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Abstract

In this communication, the single-element version of the fractional Maxwell model (single FMM) is adopted to quantify the observed behaviour of the interfacial dilational viscoelasticity. This mathematical tool is applied to the results obtained by the oscillating drop method for aqueous solutions of [...] Read more.

In this communication, the single-element version of the fractional Maxwell model (single FMM) is adopted to quantify the observed behaviour of the interfacial dilational viscoelasticity. This mathematical tool is applied to the results obtained by the oscillating drop method for aqueous solutions of ethyl lauroyl arginate (LAE). The single FMM adequately fits the experimental results, fairly well characterizing the frequency dependence of the modulus and the inherent phase-shift angle of the complex physical quantity, i.e., the interfacial dilational viscoelasticity. Further speculations are envisaged to apply the FMM to step perturbations in the time domain, allowing for the same parameter set as in the frequency domain. Full article

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10 pages, 5528 KiB

Open AccessArticle

Heat Transfer Fluids Based on Amino-Functionalized Silica Dispersed in 1,2-Propylene Glycol and in 50-50 Aqueous 1,2-Propylene Glycol

by Marta Kalbarczyk, Sebastian Skupiński and Marek Kosmulski

Colloids Interfaces 2024, 8(4), 43; https://doi.org/10.3390/colloids8040043 - 16 Jul 2024

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Abstract

1,2-propylene glycol and its 50-50 w/w mixture with water were used to prepare heat transfer fluids based on amino-functionalized silica. On top of pH-neutral dispersions (no reagents added except for the solvent and the particles), dispersions acidified with acetic acid and [...] Read more.

1,2-propylene glycol and its 50-50 w/w mixture with water were used to prepare heat transfer fluids based on amino-functionalized silica. On top of pH-neutral dispersions (no reagents added except for the solvent and the particles), dispersions acidified with acetic acid and with HCl were used to enhance the positive electric charge of silica particles. The colloidal particles had a positive zeta potential >40 mV and showed apparent particle radii of 70 nm, and these properties remained unchanged on heating up to 80 °C for up to 28 days. Full article

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12 pages, 2527 KiB

Open AccessArticle

Co-Encapsulation of Paclitaxel and Doxorubicin in Liposomes Layer by Layer

by Isaac Izcoatl Mota Díaz, Janna Douda, Patricia García López, Sandra Edith Cabrera Becerra, Miguel Ángel Gómez Álvarez, Rebeca Jiménez Rodríguez, Rafael Jurado León and Pedro López Sánchez

Colloids Interfaces 2024, 8(4), 42; https://doi.org/10.3390/colloids8040042 - 2 Jul 2024

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Abstract

The synergistic effect of antineoplastic drug co-encapsulation systems has made them highly regarded due to their improved pharmacological efficacy. Biopolymer-coated liposomes were evaluated for paclitaxel and doxorubicin co-encapsulation in MCF-7 and MDA-MB-231 breast cancer cell lines. These nanosystems are characterized by dynamic light [...] Read more.

The synergistic effect of antineoplastic drug co-encapsulation systems has made them highly regarded due to their improved pharmacological efficacy. Biopolymer-coated liposomes were evaluated for paclitaxel and doxorubicin co-encapsulation in MCF-7 and MDA-MB-231 breast cancer cell lines. These nanosystems are characterized by dynamic light scattering, transmission electron microscopy, and UV–VIS spectroscopy. The conventional and hybrid liposomal systems presented sizes of 150 to 230 nm and %EE greater than 80% for the encapsulated active ingredients. These drug-laden liposomal systems significantly decreased cell viability in both breast cancer cell lines compared with liposome-free drugs. The delivery of antineoplastic drugs in breast cancer therapy could potentially benefit from new hybrids for drug co-encapsulation. Full article

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13 pages, 10449 KiB

Open AccessArticle

Study of Interfacial Properties of Anionic–Nonionic Surfactants Based on Succinic Acid Derivatives via Molecular Dynamics Simulations and the IGMH Method

by Wannian Zhang, Feng Luo, Zhigang Gao, Haizhu Chi, Jinlong Wang, Fang Yu and Yu-Peng He

Colloids Interfaces 2024, 8(4), 41; https://doi.org/10.3390/colloids8040041 - 1 Jul 2024

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Abstract

Surfactants are widely used in fields such as oil recovery and flotation. The properties and mechanisms of surfactants can be effectively studied using molecular dynamics (MD) simulations. Herein, the aggregation behavior of surfactants was studied at the oil–water interface by MD simulation, and [...] Read more.

Surfactants are widely used in fields such as oil recovery and flotation. The properties and mechanisms of surfactants can be effectively studied using molecular dynamics (MD) simulations. Herein, the aggregation behavior of surfactants was studied at the oil–water interface by MD simulation, and the micro-morphology of surfactants was analyzed under a low concentration and saturated state at the oil–water interface, respectively. The visualization results of the MD simulation showed that DTOA was saturated at the oil–water interface at 120 surfactant molecules, whereas 160 surfactant molecules were required for BEMA. In addition, the effect of surfactant concentration on the interfacial thickness and hydrogen bond distribution was studied, with the inflection point of hydrogen bond distribution identified as a characteristic parameter for surfactant saturation at the oil–water interface. The aggregation behavior of their hydrophobic and hydrophilic chains at the oil–water interface was qualitatively assessed using order parameters. Finally, the aggregation state of surfactants in salt-containing systems was studied, and it was found that the surfactants could effectively adsorb magnesium ions and calcium ions at the oil–water interface. However, the curve of the number of hydrogen bonds varies greatly, with a possible reason being that BEMA has a different coordination manner with diverse metal ions. This study provides some original insights into both the theoretical study and practical application of anionic and nonionic surfactants. Full article

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32 pages, 4249 KiB

Open AccessFeature PaperArticle

Predictive Approach to the Phase Behavior of Polymer–Water–Surfactant–Electrolyte Systems Using a Pseudosolvent Concept

by Ji-Zen Sheu and Ramanathan Nagarajan

Colloids Interfaces 2024, 8(4), 40; https://doi.org/10.3390/colloids8040040 - 21 Jun 2024

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Abstract

A predictive approach to the phase behavior of four-component polymer–water–surfactant–electrolyte systems is formulated by viewing the four-component system as a binary polymer–pseudosolvent system, with the pseudosolvent representing water, surfactant, and the electrolyte. The phase stability of this binary system is examined using the [...] Read more.

A predictive approach to the phase behavior of four-component polymer–water–surfactant–electrolyte systems is formulated by viewing the four-component system as a binary polymer–pseudosolvent system, with the pseudosolvent representing water, surfactant, and the electrolyte. The phase stability of this binary system is examined using the framework of the lattice fluid model of Sanchez and Lacombe. In the lattice fluid model, a pure component is represented by three equation-of-state parameters: the hard-core volume of a lattice site (

v^{*}

), the number of lattice sites occupied by the component (r), and its characteristic energy (

ε^{*}

). We introduce the extra-thermodynamic postulate that r and

v^{*}

for the pseudosolvent are the same as for water and all surfactant–electrolyte composition-dependent characteristics of the pseudosolvent can be represented solely through its characteristic energy parameter. The key implication of the postulate is that the phase behavior of polymer–pseudosolvent systems will be identical for all pseudosolvents with equal values of characteristic energy, despite their varying real compositions. Based on the pseudosolvent model, illustrative phase diagrams have been computed for several four-component systems containing alkyl sulfonate/sulfate surfactants, electrolytes, and anionic or nonionic polymers. The pseudosolvent model is shown to describe all important trends in experimentally observed phase behavior pertaining to polymer and surfactant molecular characteristics. Most importantly, the pseudosolvent model allows one to construct a priori phase diagrams for any polymer–surfactant–electrolyte system, knowing just one experimental composition data for a system at the phase boundary, using available thermodynamic data on surfactants and electrolytes and without requiring any information on the polymer. Full article

(This article belongs to the Special Issue Surfactants and Interfaces)

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Colloids Interfaces, Volume 8, Issue 4 (August 2024) – 8 articles

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