Colloids and Interfaces

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13 pages, 2146 KiB

Open AccessArticle

Amplification of SERS Signal of Methotrexate Using Beta-Cyclodextrin Modified Silver Nanoparticles

by Natalia E. Markina, Irina Yu. Goryacheva and Alexey V. Markin

Colloids Interfaces 2023, 7(2), 42; https://doi.org/10.3390/colloids7020042 - 26 May 2023

Cited by 6 | Viewed by 2122

Abstract

The paper describes the use of native β-cyclodextrin (CD) for the modification of silver nanoparticles (AgNPs) in order to improve the determination of the anticancer drug methotrexate (MTX) using surface-enhanced Raman spectroscopy (SERS). A control experiment with unmodified AgNPs showed that the strong [...] Read more.

The paper describes the use of native β-cyclodextrin (CD) for the modification of silver nanoparticles (AgNPs) in order to improve the determination of the anticancer drug methotrexate (MTX) using surface-enhanced Raman spectroscopy (SERS). A control experiment with unmodified AgNPs showed that the strong SERS signal of MTX can only be achieved in alkaline media. However, competitive interactions and the strong background signal of human body fluid components significantly challenge MTX determination in real samples. While previous reports propose the use of thorough sample pretreatment (e.g., solid phase extraction), the application of CD-modified AgNPs increases the SERS signal of MTX in neutral media by seven times which enables simplifying the analysis and improving its accuracy by reducing the influence of endogenous components of body fluids. A detailed study of the synthesis conditions (CD concentration and reaction time) and SERS registration conditions (pH, NaCl concentration, dilution of urine samples) was performed to maximize the analytical signal and signal-to-noise ratio. The final assay was tested for MTX determination in artificially spiked samples of real human urine. The results demonstrated that MTX can be determined within the concentration range suitable for therapeutic drug monitoring (20–300 μg mL⁻¹) with satisfactory precision (6–15% RSD), accuracy (95–111% apparent recovery), and limit of detection (0.3 μg mL⁻¹). Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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16 pages, 26177 KiB

Open AccessArticle

Enhancing Structural Stability of Oil-Shell Microbubbles via Incorporation of a Gold Nanoparticle Protective Shell for Theranostic Applications

by Marzieh Ataei, Hsiu-Ping Yi, Aida Zahra Taravatfard, Ken Young Lin and Abraham Phillip Lee

Colloids Interfaces 2023, 7(2), 34; https://doi.org/10.3390/colloids7020034 - 23 Apr 2023

Cited by 1 | Viewed by 2288

Abstract

Phospholipid-stabilized microbubbles are utilized as contrast agents in medical ultrasound imaging, and researchers are currently investigating their potential as theranostic agents. Due to the inadequate water solubility and poor stability of numerous new therapeutics, the development of stable microbubbles with the capacity to [...] Read more.

Phospholipid-stabilized microbubbles are utilized as contrast agents in medical ultrasound imaging, and researchers are currently investigating their potential as theranostic agents. Due to the inadequate water solubility and poor stability of numerous new therapeutics, the development of stable microbubbles with the capacity to encapsulate hydrophobic therapeutics is necessary. Herein, we proposed a flow-focusing microfluidic device to generate highly monodispersed, phospholipid-stabilized dual-layer microbubbles for theranostic applications. The stability and microstructural evolution of these microbubbles were investigated by microscopy and machine-learning-assisted segmentation techniques at different phospholipid and gold nanoparticle concentrations. The double-emulsion microbubbles, formed with the combination of phospholipids and gold nanoparticles, developed a protective gold nanoparticle shell that not only acted as a steric barrier against gas diffusion and microbubble coalescence but also alleviated the progressive dewetting instability and the subsequent cascade of coalescence events. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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17 pages, 3509 KiB

Open AccessArticle

Interfacial Properties of Pea Protein Hydrolysate: The Effect of Ionic Strength

by Krystalia Sarigiannidou, Davide Odelli, Flemming Jessen, Mohammad Amin Mohammadifar, Fatemeh Ajalloueian, Mar Vall-llosera, Antonio Fernandes de Carvalho and Federico Casanova

Colloids Interfaces 2022, 6(4), 76; https://doi.org/10.3390/colloids6040076 - 7 Dec 2022

Cited by 2 | Viewed by 2397

Abstract

The effect of a tryptic hydrolysis as well as the effect of ionic strength (0–0.4 M NaCl) was investigated on the oil/water interfacial properties of soluble pea protein hydrolysate (SPPH) at neutral pH and room temperature (20 ± 0.01 °C). SEC-MALS and SDS-Page [...] Read more.

The effect of a tryptic hydrolysis as well as the effect of ionic strength (0–0.4 M NaCl) was investigated on the oil/water interfacial properties of soluble pea protein hydrolysate (SPPH) at neutral pH and room temperature (20 ± 0.01 °C). SEC-MALS and SDS-Page analysis showed that tryptic hydrolysis created a lower molecular weight polypeptide mixture, whereas FTIR analysis and DSC thermograms demonstrated a more disordered and flexible structure. The bulk properties of SPPH were studied in terms of hydrodynamic diameter and turbidity, where higher particle size (+ ~13 nm) and turbidity were observed at 0.4 M NaCl. Regarding the interfacial properties, the surface activity of SPPH improved by increasing ionic strength, with maximum interfacial pressure (14.28 mN/m) at 0.4 M NaCl. Nevertheless, the addition of NaCl negatively affected the elasticity and strength of the interfacial film, where the sample without salt exhibited the highest dilatational and shear storage modulus in all the frequencies considered. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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11 pages, 3115 KiB

Open AccessArticle

Green Synthesis of Antibacterial Silver Nanocolloids with Agroindustrial Waste Extracts, Assisted by LED Light

by Ambar Cañadas, Arleth Gualle, Karla Vizuete, Alexis Debut, Patricio Rojas-Silva, Sebastian Ponce and Lourdes M. Orejuela-Escobar

Colloids Interfaces 2022, 6(4), 74; https://doi.org/10.3390/colloids6040074 - 1 Dec 2022

Cited by 4 | Viewed by 2309

Abstract

Herein, the green synthesis of silver nanoparticles (AgNPs), assisted by LED light, using the aqueous extracts of agroindustrial waste products, such as avocado seeds (ASs), cocoa pod husks (CPHs), and orange peels (OPs), is presented. Surface plasmon resonance analysis showed faster and complete [...] Read more.

Herein, the green synthesis of silver nanoparticles (AgNPs), assisted by LED light, using the aqueous extracts of agroindustrial waste products, such as avocado seeds (ASs), cocoa pod husks (CPHs), and orange peels (OPs), is presented. Surface plasmon resonance analysis showed faster and complete NP formation when irradiated with blue LED light. Green and red light irradiation showed non- and limited nanoparticle formation. TEM analyses confirmed the semispherical morphology of the synthesized AgNPs, with the exception of OP–AgNPs, which showed agglomeration during the light irradiation. For AS–AgNPs and CPH–AgNPs, the average particle diameter was about 15 nm. Interestingly, the CPH extract demonstrated faster nanoparticle formation as compared to the AS extract (100 min vs. 250 min irradiation time, respectively). FTIR spectroscopy assessed the involvement of diverse functional groups of the bioactive phytochemicals present in the plant extracts during nanoparticle photobiosynthesis. The antioxidant activity, as determined by ferric reducing antioxidant power (FRAP) assay, varied from 1323.72 µmol TE/mL in the AS aqueous extract to 836.50 µmol TE/mL in the CPH aqueous extract. The total polyphenol content was determined according to the Folin–Ciocalteu procedure; the AS aqueous extract exhibited a higher polyphenol content (1.54 mg GAE/g) than did the CPH aqueous extract (0.948 mg GAE/g). In vitro antibacterial assays revealed that the AS–AgNPs exhibited promising antibacterial properties against pathogenic bacteria (E. Coli), whereas the CPH–AgNPs showed antibacterial activity against S. aureus and E. coli. The green synthesis of AgNPs using AS, CPH, and OP aqueous extracts reported in this work is environmentally friendly and cost-effective, and it paves the way for future studies related to agroindustrial waste valorization for the production of advanced nanomaterials, such as antibacterial AgNPs, for potential biomedical, industrial, and environmental applications. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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12 pages, 2607 KiB

Open AccessArticle

Bionanocomposite Active Packaging Material Based on Soy Protein Isolate/Persian Gum/Silver Nanoparticles; Fabrication and Characteristics

by Mahmood Alizadeh Sani, Arezou Khezerlou, Milad Tavassoli, Keyhan Mohammadi, Shokoufeh Hassani, Ali Ehsani and David Julian McClements

Colloids Interfaces 2022, 6(4), 57; https://doi.org/10.3390/colloids6040057 - 18 Oct 2022

Cited by 34 | Viewed by 3659

Abstract

In this study, nanocomposite active films were fabricated containing silver nanoparticles (SNPs) embedded within soy protein isolate (SPI)/Persian gum (PG) matrices. The physical, mechanical, and antibacterial properties of these composite films were then characterized. In addition, scanning electron microscopy (SEM), Fourier transform infrared [...] Read more.

In this study, nanocomposite active films were fabricated containing silver nanoparticles (SNPs) embedded within soy protein isolate (SPI)/Persian gum (PG) matrices. The physical, mechanical, and antibacterial properties of these composite films were then characterized. In addition, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were used to provide information about the microstructure, interactions, and crystallinity of the films. Pure SPI films had poor physicochemical attributes but the addition of PG (0.25, 0.5, or 1 wt%) improved their water vapor permeability, mechanical properties, and water solubility (WS). The moisture content (MC) of the films decreased after the introduction of PG, which was attributed to fewer free hydroxyl groups to bind to the water molecules. Our results suggest there was a strong interaction between the SPI and the PG and SNPs in the films, suggesting these additives behaved like active fillers. Optimum film properties were obtained at 0.25% PG in the SPI films. The addition of PG (0.25%) and SNPs (1%) led to a considerable increase in tensile strength (TS) and a decrease in elongation at break (EB). Furthermore, the incorporation of the SNPs into the SPI/PG composite films increased their antibacterial activity against pathogenic bacteria (Escherichia coli and Staphylococcus aureus), with the effects being more prominent for S. aureus. Spectroscopy analyses provided insights into the nature of the molecular interactions between the different components in the films. Overall, the biodegradable active films developed in this study may be suitable for utilization as eco-friendly packaging materials in the food industry. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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14 pages, 4234 KiB

Open AccessArticle

Unfolded Lipase at Interfaces Studied via Interfacial Dilational Rheology: The Impact of Urea

by Saeid Dowlati, Aliyar Javadi, Reinhard Miller, Kerstin Eckert and Matthias Kraume

Colloids Interfaces 2022, 6(4), 56; https://doi.org/10.3390/colloids6040056 - 17 Oct 2022

Cited by 5 | Viewed by 2245

Abstract

Unfolding can interrupt the activity of enzymes. Lipase, the enzyme responsible for triglyceride catalysis, can be deactivated by unfolding, which can significantly affect the yield of enzymatic processes in biochemical engineering. Different agents can induce lipase unfolding, among which we study the impact [...] Read more.

Unfolding can interrupt the activity of enzymes. Lipase, the enzyme responsible for triglyceride catalysis, can be deactivated by unfolding, which can significantly affect the yield of enzymatic processes in biochemical engineering. Different agents can induce lipase unfolding, among which we study the impact of urea as a strong denaturant. Unfolding weakens the rigidity and stability of globular proteins, thereby changing the viscoelastic properties of the protein adsorbed layers. These changes can be detected and quantified using interfacial dilational rheology. The urea-induced unfolding of lipase destructs its globular structure, making it more flexible. The interfacial tension and viscoelastic moduli of lipase adsorbed layers reduce upon the addition of urea in the range of studied concentrations. The results agree with the theory that, upon unfolding, a distal region of the loop and tail domain forms adjacent to the proximal region of the interface. The exchange of matter between these regions reduces the viscoelasticity of the unfolded lipase adsorbed layers. Additionally, unfolding reduces the rigidity and brittleness of the lipase adsorbed layers: the aged adsorbed layer of native lipase can break upon high-amplitude perturbations of the interfacial area, unlike the case for urea-induced unfolded lipase. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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9 pages, 1609 KiB

Open AccessArticle

A Molecular View of the Surface Pressure/Area Per Lipid Isotherms Assessed by FTIR/ATR Spectroscopy

by E. Anibal Disalvo, Antonio Sebastian Rosa, Jimena P. Cejas and Maria A. Frias

Colloids Interfaces 2022, 6(4), 54; https://doi.org/10.3390/colloids6040054 - 11 Oct 2022

Cited by 2 | Viewed by 2184

Abstract

The macroscopic behavior of a lipid monolayer in terms of packing and compressibility properties is classically obtained from surface pressure/area per molecule isotherms. Molecular interpretations trying to fit the II/A curves have been attempted by molecular dynamics. In this regard, the simulation is [...] Read more.

The macroscopic behavior of a lipid monolayer in terms of packing and compressibility properties is classically obtained from surface pressure/area per molecule isotherms. Molecular interpretations trying to fit the II/A curves have been attempted by molecular dynamics. In this regard, the simulation is performed by introducing parameters accounting for the lipid-lipid interaction in the monolayer plane. However, water, as an essential component of the interfacial phenomena, is not explicitly included in terms of molecular arrays. This drawback appears to be a consequence of the lack of experimental evidence that may complement the macroscopic view with the microscopic features. In this work, we propose that II/A curves can be reproduced from microscopic molecular data obtained with FTIR/ATR spectroscopy. The changes in surface pressure, in fact, changes in the surface tension of the lipid–water interphase, can be related to the acyl regions exposed to water and evaluated by the ratio of isolated-to-connected CH₂ populations. In turn, the area changes correspond to the variations in the primary and secondary hydration shells of the phosphate region. The isolated/connected CH₂ ratio represents the extension of the non-polar region exposed to water and is linked to the resulting water surface tension. The area per lipid is determined by the excluded volume of the hydration shells around the phosphate groups in correlation to the carbonyl groups. The derivative of the frequencies of the -CH₂ groups with respect to the water content gives an insight into the influence of water arrangements on the compressibility properties, which is important in understanding biologically relevant phenomena, such as osmotic stress in cells and the mechanical response of monolayers. It is concluded that the water population distributed around the different groups dominates, to a great extent, the physical properties of the lipid membranes. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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12 pages, 3639 KiB

Open AccessArticle

Single-Stranded DNA Recognition over Fluorescent Gold-Aryl Nanoparticles

by Javad B. M. Parambath, Gayathri A. Kanu, Raed O. Abu Odeh, Sanghyeon Kim, Changseok Han and Ahmed A. Mohamed

Colloids Interfaces 2022, 6(3), 42; https://doi.org/10.3390/colloids6030042 - 24 Aug 2022

Cited by 2 | Viewed by 2413

Abstract

Fluorescence labeling of gold-aryl nanoparticles, AuNPs-COOH, was achieved by the covalent derivatization with dansyl chloride (DNS-Cl) reagent (5-naphthalene-1-sulfonyl chloride) for potential ssDNA recognition. The fluorescent gold nanoparticles of AuNPs-C₆H₄-4-COO-dansyl (AuNPs-DNS) of spherical shape and a size of 19.3 ± [...] Read more.

Fluorescence labeling of gold-aryl nanoparticles, AuNPs-COOH, was achieved by the covalent derivatization with dansyl chloride (DNS-Cl) reagent (5-naphthalene-1-sulfonyl chloride) for potential ssDNA recognition. The fluorescent gold nanoparticles of AuNPs-C₆H₄-4-COO-dansyl (AuNPs-DNS) of spherical shape and a size of 19.3 ± 8.3 nm were synthesized in a carbonate-bicarbonate buffer (pH = 10.6) at 37 °C. The fluorescence emission at 475 nm was acquired using fluorescence spectroscopy and investigated using time-resolved photoluminescence. The conjugation of ssDNA to AuNPs-DNS using the freeze-thaw and salt-aging methods was confirmed by fluorescence emission quenching, gel electrophoresis separation, and lifetime decrease. Conjugated ssDNA to AuNPs-DNS using the freeze-thaw method was more efficient than the salt-aging method. The purity of ssDNA upon conjugation was measured with optical density, and the obtained A₂₆₀/A₂₈₀ ratio was in the range of 1.7–2.0. This research can be applied to other nucleotide recognition and theranostics. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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18 pages, 3101 KiB

Open AccessArticle

Phospholipids and Hyaluronan: From Molecular Interactions to Nano- and Macroscale Friction

by Sixuan Li, Lubica Macakova, Piotr Bełdowski, Per M. Claesson and Andra Dėdinaitė

Colloids Interfaces 2022, 6(3), 38; https://doi.org/10.3390/colloids6030038 - 23 Jun 2022

Cited by 2 | Viewed by 2691

Abstract

Phospholipids and hyaluronan are two key biomolecules that contribute to the excellent lubrication of articular joints. Phospholipids alone and in combination with hyaluronan have also displayed low friction forces on smooth surfaces in micro- and nanosized tribological contacts. In an effort to develop [...] Read more.

Phospholipids and hyaluronan are two key biomolecules that contribute to the excellent lubrication of articular joints. Phospholipids alone and in combination with hyaluronan have also displayed low friction forces on smooth surfaces in micro- and nanosized tribological contacts. In an effort to develop aqueous-based lubrication systems, it is highly relevant to explore if these types of molecules also are able to provide efficient lubrication of macroscopic tribological contacts involving surfaces with roughness larger than the thickness of the lubricating layer. To this end, we investigated the lubrication performance of hyaluronan, the phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and mixtures of these two components using glass surfaces in a mini-traction machine. We compared our data with those obtained using flat silica surfaces in previous atomic force microscopy studies, and we also highlighted insights on hyaluronan–phospholipid interactions gained from recent simulations. Our data demonstrate that hyaluronan alone does not provide any lubricating benefit, but DPPC alone and in mixtures with hyaluronan reduces the friction force by an order of magnitude. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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12 pages, 2174 KiB

Open AccessArticle

A Sebum-Mimetic Lipid Monolayer and Its Interaction with (Bio)Surfactants

by Ilona Jurek and Kamil Wojciechowski

Colloids Interfaces 2022, 6(2), 37; https://doi.org/10.3390/colloids6020037 - 20 Jun 2022

Viewed by 2493

Abstract

Surfactants present in cleansing formulations interact not only with the unwanted lipids accumulating on the human skin (dirt) but also with its protective lipidic layer (sebum). Development of simple models of human sebum would help to compare different surfactants and biosurfactants under the [...] Read more.

Surfactants present in cleansing formulations interact not only with the unwanted lipids accumulating on the human skin (dirt) but also with its protective lipidic layer (sebum). Development of simple models of human sebum would help to compare different surfactants and biosurfactants under the same conditions. In this contribution we propose a first monolayer model of synthetic sebum composed of lard, stearic acid, lanolin, squalane and cholesterol. The monolayer compression isotherm features a gas-liquid (G-LE1), two liquid-liquid transitions (LE1-LE2 and LE2-LC), and a collapse at π_coll = 45 mN/m. The monolayer spread on pure water and pre-compressed to π₀ = 30 mN/m was exposed to four synthetic surfactants (sodium lauryl sulfate (SLS), sodium laureth sulfate (SLES), ammonium lauryl sulfate (ALS) and cocamidopropyl betaine (CAPB)) and four plant extracts (oat (Avena sativa L.), horse chestnut (Aesculus hippocastanum L.), cowherb (Vaccaria hispanica [P. Mill.] Rauschert), soybean (Glycine max L.) and soapwort (Saponaria officinalis L.)) introduced to the subphase at a dry mass content of 1% (w/w). Three modes of the monolayer-(bio)surfactant interactions were observed: (1) complete solubilization (SLS, SLES, ALS, CAPB); (2) penetration accompanied by an increase of surface pressure and elasticity but without solubilization (horse chestnut, cowherb, soapwort); (3) no interaction (oat, soybean). Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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14 pages, 2494 KiB

Open AccessArticle

Levofloxacin and Amikacin Adsorption on Nanodiamonds: Mechanism and Application Prospects

by Tianyi Shen, Maria G. Chernysheva, Gennadii A. Badun, Andrey G. Popov, Alexander V. Egorov, Neli M. Anuchina, Ivan S. Chaschin and Natalia P. Bakuleva

Colloids Interfaces 2022, 6(2), 35; https://doi.org/10.3390/colloids6020035 - 29 May 2022

Cited by 10 | Viewed by 3296

Abstract

This research is focused on the adsorption modification of detonation nanodiamond surfaces with antibiotics for their further use as smart materials for cardiovascular surgery purposes, namely as bioprostheses modifiers. Tritium-labeled amikacin and levofloxacin were used as tracers for the adsorption process control. We [...] Read more.

This research is focused on the adsorption modification of detonation nanodiamond surfaces with antibiotics for their further use as smart materials for cardiovascular surgery purposes, namely as bioprostheses modifiers. Tritium-labeled amikacin and levofloxacin were used as tracers for the adsorption process control. We found that nanodiamonds form adsorption complexes with levofloxacin via physical adsorption, while in the case of amikacin, electrostatic attraction contributes to the formation of more stable complexes, even in the presence of electrolytes and desorbing agents (models of biological fluids). Antimicrobial characterization of nanodiamond–levofloxacin and nanodiamond–amikacin complexes indicates a reduction in the dose of antibiotics that is used as an antimicrobial agent. Therefore, the use of biomaterial based on DND complexes with antibiotics as the basis of bioprostheses will allow one either to avoid or significantly reduce the duration and intensity of antibiotics use in the postoperative period, which is critically important from the viewpoint of the development of antibiotic resistance in pathogens. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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11 pages, 1603 KiB

Open AccessArticle

Diffusiophoresis of a Soft Particle as a Model for Biological Cells

by Hiroyuki Ohshima

Colloids Interfaces 2022, 6(2), 24; https://doi.org/10.3390/colloids6020024 - 14 Apr 2022

Cited by 6 | Viewed by 3288

Abstract

We derive the general expression for the diffusiophoretic mobility of a soft particle (i.e., polyelectrolyte-coated hard particle) in a concentration gradient of electrolytes for the case in which the particle’s core size is large enough compared with the Debye length. Therefore, the particle [...] Read more.

We derive the general expression for the diffusiophoretic mobility of a soft particle (i.e., polyelectrolyte-coated hard particle) in a concentration gradient of electrolytes for the case in which the particle’s core size is large enough compared with the Debye length. Therefore, the particle surface can be regarded as planar, and the electrolyte concentration gradient is parallel to the core surface. The obtained expression can be applied for arbitrary values of the fixed charge density of the polyelectrolyte layer and the surface charge density of the particle core. We derive approximate analytic mobility expressions for soft particles of three types, i.e., (i) weakly charged soft particles, (ii) soft particles with a thick polyelectrolyte layer, in which the equilibrium electric potential deep inside the polyelectrolyte layer is equal to the Donnan potential, and (iii) soft particles with an uncharged polymer layer of finite thickness. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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Review

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15 pages, 10608 KiB

Open AccessReview

Adsorption, Surface Viscoelasticity, and Foaming Properties of Silk Fibroin at the Air/Water Interface

by Xiuying Qiao, Reinhard Miller, Emanuel Schneck and Kang Sun

Colloids Interfaces 2022, 6(3), 40; https://doi.org/10.3390/colloids6030040 - 19 Jul 2022

Cited by 1 | Viewed by 2494

Abstract

Like other proteins, the natural silk fibroin (SF) extracted from domesticated silkworms can adsorb at the air/water interface and stabilize foam due to its amphiphilic character and surface activity. At the interface, the adsorbed SF molecules experience structural reorganization and form water-insoluble viscoelastic [...] Read more.

Like other proteins, the natural silk fibroin (SF) extracted from domesticated silkworms can adsorb at the air/water interface and stabilize foam due to its amphiphilic character and surface activity. At the interface, the adsorbed SF molecules experience structural reorganization and form water-insoluble viscoelastic films, which protect foam bubbles from coalescence and rupture. The solution conditions, such as protein concentration, pH, and additives, have significant influences on the molecular adsorption, layer thickness, interfacial mechanical strength, and, thus, on the foaming properties of SF. The understanding of the relationship between the interfacial adsorption, surface viscoelasticity, and foaming properties of SF is very important for the design, preparation, and application of SF foams in different fields. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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45 pages, 7199 KiB

Open AccessReview

Proposed Methods for Testing and Comparing the Emulsifying Properties of Proteins from Animal, Plant, and Alternative Sources

by David Julian McClements, Jiakai Lu and Lutz Grossmann

Colloids Interfaces 2022, 6(2), 19; https://doi.org/10.3390/colloids6020019 - 24 Mar 2022

Cited by 37 | Viewed by 14051

Abstract

The food industry is trying to reformulate many of its products to replace functional ingredients that are chemically synthesized or isolated from animal sources (such as meat, fish, eggs, or milk) with ingredients derived from plant or microbial sources. This effort is largely [...] Read more.

The food industry is trying to reformulate many of its products to replace functional ingredients that are chemically synthesized or isolated from animal sources (such as meat, fish, eggs, or milk) with ingredients derived from plant or microbial sources. This effort is largely a result of the demand for foods that are better for the environment, human health, and animal welfare. Many new kinds of plant- or microbial-derived proteins are being isolated for potential utilization as functional ingredients by the food industry. A major challenge in this area is the lack of standardized methods to measure and compare the functional performance of proteins under conditions they might be used in food applications. This information is required to select the most appropriate protein for each application. In this article, we discuss the physicochemical principles of emulsifier functionality and then present a series of analytical tests that can be used to quantify the ability of proteins to form and stabilize emulsions. These tests include methods for characterizing the effectiveness of the proteins to promote the formation and stability of the small droplets generated during homogenization, as well as their ability to stabilize the droplets against aggregation under different conditions (e.g., pH, ionic composition, temperature, and shearing). This information should be useful to the food industry when it is trying to identify alternative proteins to replace existing emulsifiers in specific food applications. Full article

(This article belongs to the Special Issue Biocolloids and Biointerfaces)

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