Journal Description
Colloids and Interfaces
Colloids and Interfaces
is an international, peer-reviewed, open access journal on colloids and interfaces chemistry published bimonthly online by MDPI.
- Open Access— free for readers, no limits on space and color.
- High Visibility: indexed within Scopus, ESCI (Web of Science), CAPlus / SciFinder, Inspec, and other databases.
- Journal Rank: CiteScore - Q2 (Chemistry (miscellaneous))
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 21 days after submission; acceptance to publication is undertaken in 5 days (median values for papers published in this journal in the first half of 2024).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
2.5 (2023);
5-Year Impact Factor:
2.6 (2023)
Latest Articles
Co-Encapsulation of Paclitaxel and Doxorubicin in Liposomes Layer by Layer
Colloids Interfaces 2024, 8(4), 42; https://doi.org/10.3390/colloids8040042 - 2 Jul 2024
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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
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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.
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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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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
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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.
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Open AccessFeature PaperArticle
Predictive Approach to the Phase Behavior of Polymer–Water–Surfactant–Electrolyte Systems Using a Pseudosolvent Concept
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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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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
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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 ( ), the number of lattice sites occupied by the component (r), and its characteristic energy ( ). We introduce the extra-thermodynamic postulate that r and 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.
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(This article belongs to the Special Issue Surfactants and Interfaces)
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Open AccessArticle
Development of PSL-Loaded PLGA Nanoparticles for the Treatment of Allergic Contact Dermatitis
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Ryo Fujisawa, Ryuse Sakurai, Takeshi Oshizaka, Kenji Mori, Akiyoshi Saitoh, Issei Takeuchi and Kenji Sugibayashi
Colloids Interfaces 2024, 8(3), 39; https://doi.org/10.3390/colloids8030039 - 18 Jun 2024
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Allergic contact dermatitis (ACD) can easily develop once sensitization is established by exposure to small amounts of antigen, and steroids are used for treatment. In this study, we evaluated the therapeutic efficacy of prednisolone (PSL)-loaded poly(DL-lactide-co-glycolide) (PLGA) nanoparticles (NPs) on a
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Allergic contact dermatitis (ACD) can easily develop once sensitization is established by exposure to small amounts of antigen, and steroids are used for treatment. In this study, we evaluated the therapeutic efficacy of prednisolone (PSL)-loaded poly(DL-lactide-co-glycolide) (PLGA) nanoparticles (NPs) on a mouse model of contact dermatitis (CHS). Nanoparticles were prepared using a poor solvent diffusion method, and particle size distribution and mean particle size were measured using dynamic light scattering. Treatment experiments with PSL-loaded PLGA NPs were performed before and after sensitization with 1-fluoro-2,4-dinitrobenzene (DNFB), and evaluation was performed by quantifying intracutaneous IL-4 and TNF-α levels in a mouse model of CHS using ELISA. When PSL-loaded PLGA NPs were administered before sensitization, IL-4 expression was significantly decreased, and TNF-α tended to decrease in the group treated with PSL-loaded PLGA NPs compared to the non-treated group. When PSL-loaded PLGA NPs were administered after sensitization, IL-4 expression was significantly decreased in the group treated with PSL-loaded PLGA NPs compared to the non-treated group. In both cases, there were no significant differences between the PSL-loaded PLGA NP treatment group and the PSL-containing ointment group. These results suggest that, in the treatment of CHS, PSL-loaded PLGA NPs show a certain therapeutic effect when preadministration.
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Open AccessArticle
An Investigation of the Effect of pH on Micelle Formation by a Glutamic Acid-Based Biosurfactant
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Jacob D. Mayer, Robert M. Rauscher, Shayden R. Fritz, Yayin Fang, Eugene J. Billiot, Fereshteh H. Billiot and Kevin F. Morris
Colloids Interfaces 2024, 8(3), 38; https://doi.org/10.3390/colloids8030038 - 11 Jun 2024
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NMR spectroscopy, molecular modeling, and conductivity experiments were used to investigate micelle formation by the amino acid-based surfactant tridecanoic L-glutamic acid. Amino acid-based biosurfactants are green alternatives to surfactants derived from petroleum. NMR titrations were used to measure the monomeric surfactant’s primary and
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NMR spectroscopy, molecular modeling, and conductivity experiments were used to investigate micelle formation by the amino acid-based surfactant tridecanoic L-glutamic acid. Amino acid-based biosurfactants are green alternatives to surfactants derived from petroleum. NMR titrations were used to measure the monomeric surfactant’s primary and gamma (γ) carboxylic acid pKa values. Intramolecular hydrogen bonding within the surfactant’s headgroup caused the primary carboxylic acid to be less acidic than the corresponding functional group in free L-glutamic acid. Likewise, intermolecular hydrogen bonding caused the micellar surfactant’s γ carboxylic functional group to be less acidic than the corresponding monomer value. The binding of four positive counterions to the anionic micelles was also investigated. At pH levels below 7.0 when the surfactant headgroup charge was −1, the micelle hydrodynamic radii were larger (~30 Å) and the mole fraction of micelle-bound counterions was in the 0.4–0.7 range. In the pH range of 7.0–10.5, the micelle radii decreased with increasing pH and the mole fraction of micelle bound counterions increased. These observations were attributed to changes in the surfactant headgroup charge with pH. Above pH 10.5, the counterions deprotonated and the mole fraction of micelle-bound counterions decreased further. Finally, critical micelle concentration measurements showed that the micelles formed at lower concentrations at pH 6 when the headgroup charge was predominately −1 and at higher concentrations at pH 7 where headgroups had a mixture of −1 and −2 charges in solution.
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Open AccessArticle
Biocomposite Films of Amylose Reinforced with Polylactic Acid by Solvent Casting Method Using a Pickering Emulsion Approach
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Marwa Faisal, Jacob Judas Kain Kirkensgaard, Bodil Jørgensen, Peter Ulvskov, Max Rée, Sue Kang, Nikolai Andersson, Mikkel Jørgensen, Jonas Simonsen, Kim H. Hebelstrup and Andreas Blennow
Colloids Interfaces 2024, 8(3), 37; https://doi.org/10.3390/colloids8030037 - 9 Jun 2024
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Binary and ternary blends of amylose (AM), polylactic acid (PLA), and glycerol were prepared using a Pickering emulsion approach. Various formulations of AM/PLA with low PLA contents ranging from 3% to 12% were mixed with AM matrix and reinforced with 25% cellulose nanofibers
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Binary and ternary blends of amylose (AM), polylactic acid (PLA), and glycerol were prepared using a Pickering emulsion approach. Various formulations of AM/PLA with low PLA contents ranging from 3% to 12% were mixed with AM matrix and reinforced with 25% cellulose nanofibers (CNF), and PLA-grafted cellulose nanofibers (g-CNF), the latter to enhance miscibility. Polymeric films were fabricated through solvent casting and characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Wide-Angle X-ray Scattering (WAXS), and the evaluations of physical, mechanical properties, and wettability were performed using contact angle measurements. The binary blends of AM and PLA produced films suitable for packaging, pharmaceutical, or biomedical applications with excellent water barrier properties. The ternary blends of AM/CNF/PLA and AM/g-CNF/PLA nanocomposite films demonstrated enhanced tensile strength and reduced water permeability compared to AM/PLA films. Adding g-CNF resulted in better homogeneity and increased relative crystallinity from 33% to 35% compared to unmodified CNF. The application of Pickering emulsion in creating AM-based CNF/ PLA composites resulted in a notable enhancement in tensile strength by 47%. This study presents an effective approach for producing biodegradable and reinforced PLA-based nanocomposite films, which show promise as bio-nanocomposite materials for food packaging applications.
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Open AccessArticle
Diffusiophoresis of a Charged Soft Sphere in a Charged Spherical Cavity
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Wei-Zhi Chen and Huan-Jang Keh
Colloids Interfaces 2024, 8(3), 36; https://doi.org/10.3390/colloids8030036 - 2 Jun 2024
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The quasi-steady diffusiophoresis of a soft particle composed of an uncharged hard sphere core and a uniformly charged porous surface layer in a concentric charged spherical cavity full of a symmetric electrolyte solution with a concentration gradient is analyzed. By using a regular
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The quasi-steady diffusiophoresis of a soft particle composed of an uncharged hard sphere core and a uniformly charged porous surface layer in a concentric charged spherical cavity full of a symmetric electrolyte solution with a concentration gradient is analyzed. By using a regular perturbation method with small fixed charge densities of the soft particle and cavity wall, the linearized electrokinetic equations relevant to the fluid velocity field, electric potential profile, and ionic concentration distributions are solved. A closed-form formula for the diffusiophoretic (electrophoretic and chemiphoretic) velocity of the soft particle is obtained as a function of the ratios of the core-to-particle radii, particle-to-cavity radii, particle radius to the Debye screening length, and particle radius to the permeation length in the porous layer. In typical cases, the confining charged cavity wall significantly influences the diffusiophoresis of the soft particle. The fluid flow caused by the diffusioosmosis (electroosmosis and chemiosmosis) along the cavity wall can considerably change the diffusiophoretic velocity of the particle and even reverse its direction. In general, the diffusiophoretic velocity decreases with increasing core-to-particle radius ratios, particle-to-cavity radius ratios, and the ratio of the particle radius to the permeation length in the porous layer, but increases with increasing ratios of the particle radius to the Debye length.
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Open AccessFeature PaperArticle
Silk Fibroin Self-Assembly at the Air–Water Interface
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Olga Yu. Milyaeva, Alexander V. Akentiev, Alexey G. Bykov, Reinhard Miller, Anastasiya R. Rafikova, Kseniya Yu. Rotanova and Boris A. Noskov
Colloids Interfaces 2024, 8(3), 35; https://doi.org/10.3390/colloids8030035 - 2 Jun 2024
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Amphiphilic silk fibroin (SF) forms stable adsorption layers at the air–water interface. The range of the investigated protein concentrations can be divided into two parts according to the peculiarities of the surface layer properties. At protein concentrations from 0.0005 to 0.01 mg/mL, the
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Amphiphilic silk fibroin (SF) forms stable adsorption layers at the air–water interface. The range of the investigated protein concentrations can be divided into two parts according to the peculiarities of the surface layer properties. At protein concentrations from 0.0005 to 0.01 mg/mL, the dynamic surface elasticity monotonically increases with the concentration and surface age and reaches values of up to 220 mN/m. In this range, the adsorption layer compression leads to a fast increase of the surface pressure. In the second part (>0.01 mg/mL), the surface elasticity decreases again and the kinetic dependences of the film thickness and adsorbed amount change only a little. In this case, the layer compression leads only to a slight increase of the surface pressure. These two types of behavior can be attributed to the distinctions in the protein aggregation in the surface layer. Atomic force microscopy (AFM) investigations of the layers transferred from the liquid surface onto a mica surface by the Langmuir–Schaefer method show some peculiarities of the layer morphology in the intermediate concentration range (~0.02 mg/mL).
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Open AccessArticle
The Role of Adsorption Phenomena in ac Conductivity Measurements of Dielectric Nanoparticle Suspensions
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Ioulia Chikina and Andrey Varlamov
Colloids Interfaces 2024, 8(3), 34; https://doi.org/10.3390/colloids8030034 - 28 May 2024
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The authors of numerous measurements of conductivity for suspensions of nanoparticles of various types carried out in the last decade came to the general conclusion that the well-known Maxwell’s theory is not applicable to quantitative explanation of the properties of such systems. In
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The authors of numerous measurements of conductivity for suspensions of nanoparticles of various types carried out in the last decade came to the general conclusion that the well-known Maxwell’s theory is not applicable to quantitative explanation of the properties of such systems. In the present work, we demonstrate that the Maxwell’s theory can be still applicable even for such systems, but the specifics of the standard ac measurements have to be correctly taken into account. Namely, the dependence of the capacitance of “metal–electrolyte” cuvette boundaries on nanoparticle adsorption, which in its turn dramatically depends on nanoparticle concentration, has to be taken into account. The latter circumstance strongly (via the characteristic of the circuit) affects the results of conductivity measurements. We propose the new algorithm of the impedance measurement data analysis for the particles’ concentration dependence of conductivity (where is the volume fraction of nanoparticles in suspension) for the suspensions of the diamante nanoparticles in alcohol which demonstrates the adequate correspondence of the Maxwell’s theory to the available experimental findings.
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Open AccessArticle
Discontinuous Shear Thickening of Suspensions of Magnetic Particles in Relation to the Polymer Coating on Their Surfaces
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Georges Bossis, Olga Volkova and Yan Grasselli
Colloids Interfaces 2024, 8(3), 33; https://doi.org/10.3390/colloids8030033 - 17 May 2024
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The phenomenon of discontinuous shear thickening (DST) is observed in suspensions of solid particles with a very high-volume fraction. It is characterized by an abrupt decrease in the shear rate for critical stress during a ramp of stress. This behavior can be reproduced
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The phenomenon of discontinuous shear thickening (DST) is observed in suspensions of solid particles with a very high-volume fraction. It is characterized by an abrupt decrease in the shear rate for critical stress during a ramp of stress. This behavior can be reproduced in numerical simulations by introducing a local friction between two particles above a given local force. We present experimental results showing this DST behavior obtained with suspensions of magnetic (iron) and nonmagnetic (calcium carbonate) particles and different amounts of a superplasticizer molecule used in the cement industry. For both types of particles, the same behavior was observed with first an increase in critical stress with the amount of plasticizer followed by a decrease at higher concentrations but with a larger viscosity before critical stress was reached. At a low concentration of plasticizer, the low critical stress is interpreted by the local sliding of plasticizer molecules on the surface of particles. At higher concentrations, when total coverage is achieved, the critical stress is higher since it has to remove the molecules out of the surface. At still higher concentrations, the increase in viscosity is explained by the formation of multilayers of molecules on the surface of the particles. This interpretation is supported by the measurement of the adsorption isotherm of the plasticizer on the surface of the particles.
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(This article belongs to the Special Issue Rheology of Complex Fluids and Interfaces)
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Flowable Electrodes from Colloidal Suspensions of Thin Multiwall Carbon Nanotubes
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Massinissa Hamouma, Wilfrid Neri, Xavier Bril, Jinkai Yuan, Annie Colin, Nicolas Brémond and Philippe Poulin
Colloids Interfaces 2024, 8(3), 32; https://doi.org/10.3390/colloids8030032 - 17 May 2024
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Flowable electrodes, a versatile alternative to traditional solid electrodes for electrochemical applications, exhibit challenges of high viscosity and carbon content, limiting flow and device performances. This study introduces colloidal suspensions of thin multiwall carbon nanotubes (MWCNTs) with diameters of 10–15 nm as electrode
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Flowable electrodes, a versatile alternative to traditional solid electrodes for electrochemical applications, exhibit challenges of high viscosity and carbon content, limiting flow and device performances. This study introduces colloidal suspensions of thin multiwall carbon nanotubes (MWCNTs) with diameters of 10–15 nm as electrode materials. These thin nanotubes, stabilized in water with a surfactant, form percolated networks, exhibiting high conductivity (50 ms/cm) and stability at a low carbon content (below 2 wt%). Colloidal clustering is enhanced by weak depletion attractive interactions. The resulting suspensions display yield stress and a shear thinning behavior with a low consistency index. They can easily flow at a nearly constant shear over a broad range of shear rates. They remain electrically conductive under shear, making them a promising option for flow electrochemical applications. This work suggests that the use of depletion-induced MWVNT aggregates addresses crucial issues in flow electrochemical applications, such as membrane fragility, operating energy, and pressure. These conductive colloidal suspensions thereby offer potential advancements in device performance and lifespan.
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Open AccessReview
A Review of Investigations and Applications of Biocides in Nanomaterials and Nanotechnologies
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Assem Issayeva, Altynay Sharipova, Saule Aidarova, Galiya Madybekova, Jaroslav Katona, Seitzhan Turganbay and Reinhard Miller
Colloids Interfaces 2024, 8(3), 31; https://doi.org/10.3390/colloids8030031 - 16 May 2024
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In recent years, the development of nanomaterials with biocidal properties has received considerable attention due to their potential applications in various industries, including food, medicine, and cultural heritage preservation. The growing demand for coatings with antibacterial properties has sparked interest from industrial sectors
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In recent years, the development of nanomaterials with biocidal properties has received considerable attention due to their potential applications in various industries, including food, medicine, and cultural heritage preservation. The growing demand for coatings with antibacterial properties has sparked interest from industrial sectors in exploring the incorporation of biocides into these materials. Coatings are prone to microbial growth, which can cause damage such as cracking, discoloration, and staining. To combat these problems, the integration of biocides into coatings is a crucial strategy. Biocide-embedded nanomaterials offer numerous advantages, including high efficiency in small quantities, ease of application, good chemical stability, low toxicity, and non-bioaccumulation. Encapsulated nanobiocides are particularly attractive to the agro-industry, because they can be less toxic than traditional biocides while still effectively controlling microbial contamination. To fully exploit the benefits of nanobiocides, future research should focus on optimizing their synthesis, formulation, and delivery methods. The purpose of this review is to summarize the current status of biocide nanomaterials, discuss potential future research directions, and highlight research methods, the development of new forms of nanomaterials, and studies of their physico-chemical properties. Biocide nanocapsules of DCOIT (4,5-Dichloro-2-octyl-2H-isothiazol-3-one) are chosen as an example to illustrate the research pathways.
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(This article belongs to the Special Issue Exclusive Papers of the Editorial Board Members of Colloids and Interfaces 2024)
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Open AccessArticle
Effect of Asphaltenes and Asphaltene Dispersants on Wax Precipitation and Treatment
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Oualid M’barki, John Clements and Quoc P. Nguyen
Colloids Interfaces 2024, 8(3), 30; https://doi.org/10.3390/colloids8030030 - 14 May 2024
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A detailed understanding of the interactions between wax and asphaltenes with other components of crude oils and the effect of treatments with paraffin inhibitors (PIs) and asphaltene dispersants (ADs), with a focus on identifying specific structure-activity relationships, is necessary to develop effective flow
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A detailed understanding of the interactions between wax and asphaltenes with other components of crude oils and the effect of treatments with paraffin inhibitors (PIs) and asphaltene dispersants (ADs), with a focus on identifying specific structure-activity relationships, is necessary to develop effective flow assurance strategies. The morphological and rheological consequences of treating wax and asphaltenes in oils of differing composition with a series of ADs having structural features in common with an alpha olefin-maleic anhydride (AO-MA) comb-like copolymer PI were assessed alone and in combination with said PI. Of the four ADs studied, two were identified as being effective dispersants of asphaltenes in heptane-induced instability tests and in a West Texas (WT) crude. The degree to which a low concentration of asphaltenes stabilizes wax in the absence of treatment additives is lessened in oils having greater aromatic fractions. This is because these stabilizing interactions are replaced by more energetically favorable aromatic–asphaltene interactions, increasing oil viscosity. Treatment with AD alone also reduces the extent of wax–asphaltene interactions, increasing oil viscosity. In concert with the PI, treatment with the AD having greater structural similarity with the PI appears to improve wax solubility in both the presence and absence of asphaltenes. However, the viscosity of the treated oils is greater than that of the oil treated with PI alone, while treatment with AD having lesser structural similarity with the PI does not adversely affect oil viscosity. These data suggest that rather than treating both wax and asphaltenes, AD may poison the function of the PI. These data illuminate the pitfalls of designing flow assurance additives to interact with both wax and asphaltenes and developing treatment plans.
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(This article belongs to the Special Issue Crude Oil Recovery)
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Vesicle Morphogenesis in Amphiphilic Triblock Copolymer Solutions
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Senyuan Liu, Mohammad Sadegh Samie and Radhakrishna Sureshkumar
Colloids Interfaces 2024, 8(3), 29; https://doi.org/10.3390/colloids8030029 - 6 May 2024
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Coarse-grained molecular dynamics simulations are employed to investigate the spatiotemporal evolution of vesicles (polymersomes) through the self-assembly of randomly distributed amphiphilic BAB triblock copolymers with hydrophilic A and hydrophobic B blocks in an aqueous solution. The vesiculation pathway consists of several intermediate structures,
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Coarse-grained molecular dynamics simulations are employed to investigate the spatiotemporal evolution of vesicles (polymersomes) through the self-assembly of randomly distributed amphiphilic BAB triblock copolymers with hydrophilic A and hydrophobic B blocks in an aqueous solution. The vesiculation pathway consists of several intermediate structures, such as an interconnected network of copolymer aggregates, a cage of cylindrical micelles, and a lamellar cage. The cage-to-vesicle transition occurs at a constant aggregation number and practically eliminates the hydrophobic interfacial area between the B block and solvent. Molecular reorganization underlying the sequence of morphology transitions from a cage-like aggregate to a vesicle is nearly isentropic. The end-to-end distances of isolated copolymer chains in solution and those within a vesicular assembly follow lognormal probability distributions. This can be attributed to the preponderance of folded chain configurations in which the two hydrophobic end groups of a given chain stay close to each other. However, the probability distribution of end-to-end distances is broader for chains within the vesicle as compared with that of a single chain. This is due to the swelling of the folded configurations within the hydrophobic bilayer. Increasing the hydrophobicity of the B block reduces the vesiculation time without qualitatively altering the self-assembly pathway.
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Water-Based Bi2S3 Nano-Inks Obtained with Surfactant-Assisted Liquid Phase Exfoliation and Their Direct Processing into Thin Films
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Micaela Pozzati, Felix Boll, Matteo Crisci, Sara Domenici, Francesco Scotognella, Bernd Smarsly, Teresa Gatti and Mengjiao Wang
Colloids Interfaces 2024, 8(3), 28; https://doi.org/10.3390/colloids8030028 - 30 Apr 2024
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Bi2S3 has gained considerable attention as a semiconductor for its versatile functional properties, finding application across various fields, and liquid phase exfoliation (LPE) serves as a straightforward method to produce it in nano-form. Till now, the commonly used solvent for
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Bi2S3 has gained considerable attention as a semiconductor for its versatile functional properties, finding application across various fields, and liquid phase exfoliation (LPE) serves as a straightforward method to produce it in nano-form. Till now, the commonly used solvent for LPE has been N-Methyl-2-pyrrolidone, which is expensive, toxic and has a high boiling point. These limitations drive the search for more sustainable alternatives, with water being a promising option. Nonetheless, surfactants are necessary for LPE in water due to the hydrophobic nature of Bi2S3, and organic molecules with amphoteric characteristics are identified as suitable surfactants. However, systematic studies on the use of ionic surfactants in the LPE of Bi2S3 have remained scarce until now. In this work, we used sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS) and sodium hexadecyl sulfonate (SHS) as representative species and we present a comprehensive investigation into their effects on the LPE of Bi2S3. Through characterizations of the resulting products, we find that all surfactants effectively exfoliate Bi2S3 into few-layer species. Notably, SDBS demonstrates superior stabilization of the 2D layers compared to the other surfactants, while SHS becomes the most promising surfactant for obtaining products with high yield. Moreover, the resulting nano-inks are used for fabricating films using spray-coating, reaching a fine tuning of band gap by controlling the number of cycles, and paving the way for the utilization of 2D Bi2S3 in optoelectronic devices.
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Open AccessArticle
Rheological Behaviors and Fractional Viscoelastic Modeling of Glucopone (APG)/Water/Hydrocarbons Solutions
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Mohamed A. Siddig
Colloids Interfaces 2024, 8(3), 27; https://doi.org/10.3390/colloids8030027 - 24 Apr 2024
Abstract
The aims of this work are to study the rheological behaviors of a microemulsion of Glucopone–water–hydrocarbon systems and to use a fractional model to describe several experimental results of these systems. Four different types of hydrocarbons were considered. The frequency dependent storage, G
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The aims of this work are to study the rheological behaviors of a microemulsion of Glucopone–water–hydrocarbon systems and to use a fractional model to describe several experimental results of these systems. Four different types of hydrocarbons were considered. The frequency dependent storage, G′, and loss modulus, G″, were investigated below the critical strain. The critical strain was found to decrease as the alkane chain lengths increased, while the opposite behavior was observed for zero shear viscosity, η0. Most of the microemulsions exhibited stable elastic fluid behavior (G′ > G″) below 10 rad s−1 angular frequency. For all systems, elastic modulus values were found to be greater than loss modulus in the frequency range studied, indicating more elastic behaviors. Shear-thinning behaviors were observed, and the complex viscosity decreased with an increase in hydrocarbon chain lengths. The effects of hydrocarbon types on the rheological behaviors were more profound in the dodecane systems which showed maximum values of G′ and η0. The Friedrich–Braun model was introduced and was used to describe several experimental results on Alkyl polyglocoside solutions. Fractional rheology successfully described the viscoelastic phenomena in Glucopone surfactant solutions and the comparisons between the experimental results and the theoretical predictions were found to be satisfactory.
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(This article belongs to the Special Issue Rheology of Complex Fluids and Interfaces)
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Open AccessArticle
Caffeine Adsorption on a Thermally Modified Bentonite: Adsorbent Characterization, Experimental Design, Equilibrium and Kinetics
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Javier A. Quintero-Jaramillo, Javier Ignacio Carrero and Nancy R. Sanabria-González
Colloids Interfaces 2024, 8(2), 26; https://doi.org/10.3390/colloids8020026 - 15 Apr 2024
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Caffeine is a chemical compound found in various products such as coffee, tea, and energy drinks; therefore, it is common in wastewater and surface water. The present study investigated caffeine adsorption on a thermally modified bentonite-type clay. The effects of the heat treatment
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Caffeine is a chemical compound found in various products such as coffee, tea, and energy drinks; therefore, it is common in wastewater and surface water. The present study investigated caffeine adsorption on a thermally modified bentonite-type clay. The effects of the heat treatment of the adsorbent over the temperature range of 60–500 °C, as well as the initial pH of the solution, stirring speed, and contact time, on the removal of caffeine were analyzed. The adsorbent was characterized by XRF, XRD, FT–IR, thermal analysis (TGA–DSC), and N2 physisorption at 77 K. The response surface methodology (RSM) based on a central composite design (CCD) was used to evaluate and optimize the adsorption of caffeine in aqueous solution. The maximum adsorption capacity of caffeine obtained with the Langmuir model was 80.3 ± 2.1 mg/g (0.41 ± 0.01 mmol/g) at 25 °C under equilibrium conditions (initial pH = 8.0, stirring speed = 400 rpm, contact time = 120 min). A kinetic study showed that the pseudo-second-order and Elovich models adequately describe the adsorption process. Bentonite thermally modified at 400 °C can be considered a low-cost adsorbent with potential application for removing caffeine in aqueous media.
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Adsorption Layer Properties and Foam Behavior of Aqueous Solutions of Whey Protein Isolate (WPI) Modified by Vacuum Cold Plasma (VCP)
by
Elham Ommat Mohammadi, Samira Yeganehzad, Mohammad Ali Hesarinejad, Mohsen Dabestani, Regine von Klitzing, Reinhard Miller and Emanuel Schneck
Colloids Interfaces 2024, 8(2), 25; https://doi.org/10.3390/colloids8020025 - 9 Apr 2024
Abstract
For years, cold plasma processing has been used as a non-thermal technology in industries such as food. As interfacial properties of protein play a remarkable role in many processes, this study investigates the effect of cold plasma on the foaming and interfacial behavior
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For years, cold plasma processing has been used as a non-thermal technology in industries such as food. As interfacial properties of protein play a remarkable role in many processes, this study investigates the effect of cold plasma on the foaming and interfacial behavior of WPI. The objective of this study is to evaluate the effect of different gases (air, 1:1 argon–air mixture, and sulfur hexafluoride (SF6)) used in low-pressure cold plasma (VCP) treatments of whey protein isolate (WPI) on the surface and foaming behavior of aqueous WPI solutions. Dynamic surface dilational elasticity, surface tension isotherms, surface layer thickness, and the foamability and foam stability were investigated in this study. VCP treatment did not significantly affect the adsorption layer thickness. However, an increase in induction time, surface pressure equilibrium value, and aggregated size is observed after SF6VCP treatment, which can be attributed to the reaction of WPI with the reactive SF6 species of the cold plasma. The surface dilational elastic modulus increased after VCP treatment, which can be related to the increased mechanical strength of the protein layer via sulfonation and aggregate formation. VCP treatment of WPI increases the foam stability, while the average diameter of foam bubbles and liquid drainage in the foam depends on the gas used for the cold plasma.
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(This article belongs to the Special Issue Proteins at the Interface)
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In Vitro Gastrointestinal Release of Chlorogenic Acid and Curcumin Co-Encapsulated in Double Emulsions with the Outer Interface Stabilized by Cellulose Nanocrystals
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Javier Paredes-Toledo, Javier Herrera, Paulo Díaz-Calderón, Paz Robert and Begoña Giménez
Colloids Interfaces 2024, 8(2), 24; https://doi.org/10.3390/colloids8020024 - 9 Apr 2024
Abstract
A Pickering double emulsion (DE) with an outer (O:W2) interface stabilized by cellulose nanocrystals (DE-CNC) was designed as a co-delivery systems for chlorogenic acid (CA) and curcumin, then compared with a control DE emulsion with an O:W2 interface stabilized with
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A Pickering double emulsion (DE) with an outer (O:W2) interface stabilized by cellulose nanocrystals (DE-CNC) was designed as a co-delivery systems for chlorogenic acid (CA) and curcumin, then compared with a control DE emulsion with an O:W2 interface stabilized with sodium caseinate (DE-NaCas). DE-CNC was more resistant to creaming during storage (6.79%, day 42) and showed higher encapsulation efficiency (EE) of CA (>90%). Conversely, both DEs exhibited similarly high EE for curcumin (>97%). The ζ-potential values were highly negative in both DEs, but tended to be lower in DE-CNC due to the highly negative charge of the CNCs. DE-CNC allowed for a steady release of CA during the oral, gastric, and intestinal phases of digestion, while a total release of CA was already observed in the gastric phase in case of DE-NaCas. The bioaccessibility of CA was similar in both DEs (~57–58%). Curcumin was mainly released in the intestinal phase with both DEs, reaching slightly lower bioaccessibility values with DE-CNC. The use of CNCs as a stabilizer for the outer interface of DEs is a promising strategy to increase the stability and EE of these systems, providing oral co-delivery vehicles capable of releasing significantly bioactive compounds during the intestinal phase of digestion.
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(This article belongs to the Special Issue Recent Advances on Emulsions and Applications: 2nd Edition)
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Oil/Brine Screening for Improved Fluid/Fluid Interactions during Low-Salinity Water Flooding
by
Jose Villero-Mandon, Peyman Pourafshary and Masoud Riazi
Colloids Interfaces 2024, 8(2), 23; https://doi.org/10.3390/colloids8020023 - 1 Apr 2024
Abstract
Low-salinity water flooding/smart water flooding (LSWF/SWF) are used for enhanced oil recovery (EOR) because of the improved extraction efficiency. These methods are more environmentally friendly and in many scenarios more economical for oil recovery. They are proven to increase recovery factors (RFs) by
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Low-salinity water flooding/smart water flooding (LSWF/SWF) are used for enhanced oil recovery (EOR) because of the improved extraction efficiency. These methods are more environmentally friendly and in many scenarios more economical for oil recovery. They are proven to increase recovery factors (RFs) by between 6 and 20%, making LSWF/SWF technologies that should be further evaluated to replace conventional water flooding or other EOR methods. Fluid/fluid interaction improvements include interfacial tension (IFT) reduction, viscoelastic behavior (elastic properties modification), and microemulsion generation, which could complement the main mechanisms, such as wettability alteration. In this research, we evaluate the importance of fluid/fluid mechanisms during LSWF/SWF operations. Our study showed that a substantial decrease in IFT occurs when the oil asphaltene content is in the range of 0% to 3 wt.%. An IFT reduction was observed at low salinity (0–10,000 ppm) and a specific oil composition condition. Optimal IFT occurs at higher divalent ion concentrations when oil has low asphaltene content. For the oil with high asphaltene content, the sulfates concentration controls the IFT alteration. At high asphaltene concentrations, the formation of micro-dispersion is not effective to recover oil, and only a 5% recovery factor improvement was observed. The presence of asphaltene at the oil/low-salinity brine interface increases the energy required to disrupt it, inducing significant changes in the elastic moduli. In cases of low asphaltene content, the storage modulus demonstrates optimal performance at higher divalent concentrations. Conversely, at high asphaltene concentrations, the dominant factors to control the interface are paraffin content and temperature.
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(This article belongs to the Special Issue Crude Oil Recovery)
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