Nanomaterials

Editorial

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4 pages, 178 KiB

Open AccessEditorial

Special Issue “Micro/Nano Emulsions: Smart Colloids for Multiple Applications”

by Ruggero Angelico

Nanomaterials 2022, 12(21), 3734; https://doi.org/10.3390/nano12213734 - 24 Oct 2022

Viewed by 903

Abstract

Microemulsions are known as thermodynamically stable nanodispersions driven by spontaneous emulsification and are commonly prepared as transparent mixtures composed of oil, water, a surfactant, and a cosurfactant [...] Full article

(This article belongs to the Special Issue Micro/Nano Emulsions: Smart Colloids for Multiple Applications)

Research

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11 pages, 3905 KiB

Open AccessArticle

Influence of Chymosin on Physicochemical and Hydrolysis Characteristics of Casein Micelles and Individual Caseins

by Chun-Chi Chen, Liang-Yu Chen, Wen-Tai Li, Ken-Lin Chang, Meng-I Kuo, Chao-Jung Chen and Jung-Feng Hsieh

Nanomaterials 2021, 11(10), 2594; https://doi.org/10.3390/nano11102594 - 1 Oct 2021

Cited by 7 | Viewed by 2619

Abstract

The effects of chymosin on the physicochemical and hydrolysis characteristics of casein micelles and individual caseins were investigated. Adding 0.03 units of chymosin/mL led to the casein micelles in skim milk coagulating after a 3 h incubation period at 30 °C. SDS–PAGE investigation [...] Read more.

The effects of chymosin on the physicochemical and hydrolysis characteristics of casein micelles and individual caseins were investigated. Adding 0.03 units of chymosin/mL led to the casein micelles in skim milk coagulating after a 3 h incubation period at 30 °C. SDS–PAGE investigation showed that β-CN, κ-CN, α_s-CN, and a portion of β-lactoglobulin (β-LG) in the milk supernatant fraction (MSF) were precipitated into the milk pellet fraction (MPF). The mean particle size of the MSF with chymosin decreased from 254.4 nm to 179.2 nm after a 3 h incubation period. Mass spectrometry and SDS–PAGE analysis suggested that chymosin hydrolyzed individual β-CN, κ-CN, and α_s-CN, but not β-LG. Chymosin hydrolysis led to a decrease in the molecular weights of the hydrolyzed β-CN, κ-CN, and α_s-CN. Particle size analysis indicated that there was no difference in the particle size distribution of hydrolyzed β-CN and α_s-CN. Moreover, our outcomes demonstrated that the hydrolysis of κ-CN by chymosin occurs before that of β-CN and α_s-CN. Full article

(This article belongs to the Special Issue Micro/Nano Emulsions: Smart Colloids for Multiple Applications)

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13 pages, 2296 KiB

Open AccessArticle

Phase Inversion and Interfacial Layer Microstructure in Emulsions Stabilized by Glycosurfactant Mixtures

by Rodolfo Esposito, Domenico Cavasso, Marcella Niccoli and Gerardino D’Errico

Nanomaterials 2021, 11(2), 331; https://doi.org/10.3390/nano11020331 - 27 Jan 2021

Cited by 7 | Viewed by 2526

Abstract

Identification of strategies to prolong emulsion kinetic stability is a fundamental challenge for many scientists and technologists. We investigated the relationship between the emulsion stability and the surfactant supramolecular organization at the oil–water interface. The pseudo-phase diagrams of emulsions formed by water and, [...] Read more.

Identification of strategies to prolong emulsion kinetic stability is a fundamental challenge for many scientists and technologists. We investigated the relationship between the emulsion stability and the surfactant supramolecular organization at the oil–water interface. The pseudo-phase diagrams of emulsions formed by water and, alternatively, a linear or a branched oil, stabilized by mixtures of two sugar-based surfactants, Span80 and Tween80, are presented. The surfactant ordering and dynamics were analyzed by electron paramagnetic resonance (EPR) spectroscopy. In Oil-in-Water (O/W) emulsions, which are stable for more than four days, disordered surfactant tails formed a compact and viscous layer. In Water-in-Oil (W/O) emulsions, whose stability is much lower, surfactants formed an ordered layer of extended tails pointing toward the continuous apolar medium. If linear oil was used, a narrow range of surfactant mixture composition existed, in which emulsions did not demix in the whole range of water/oil ratio, thus making it possible to study the phase inversion from O/W to W/O structures. While conductometry showed an abrupt inversion occurring at a well-defined water/oil ratio, the surfactant layer microstructure changed gradually between the two limiting situations. Overall, our results demonstrate the interconnection between the emulsion stability and the surfactant layer microstructuring, thus indicating directions for their rational design. Full article

(This article belongs to the Special Issue Micro/Nano Emulsions: Smart Colloids for Multiple Applications)

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14 pages, 1109 KiB

Open AccessArticle

Bioinspired Nanoemulsions Stabilized by Phosphoethanolamine and Phosphoglycerol Lipids

by Carlo Caianiello, Marcellino D'Avino, Domenico Cavasso, Luigi Paduano and Gerardino D'Errico

Nanomaterials 2020, 10(6), 1185; https://doi.org/10.3390/nano10061185 - 18 Jun 2020

Cited by 5 | Viewed by 2410

Abstract

Water-in-oil (W/O) nanoemulsions stabilized by phospholipids (PLs) are increasingly exploited in a wide spectrum of applications, from pharmaceuticals to food and cosmetic formulations. In this work, we report the design and optimization of an innovative emulsion based on a mixture of phosphoethanolamine (PE) [...] Read more.

Water-in-oil (W/O) nanoemulsions stabilized by phospholipids (PLs) are increasingly exploited in a wide spectrum of applications, from pharmaceuticals to food and cosmetic formulations. In this work, we report the design and optimization of an innovative emulsion based on a mixture of phosphoethanolamine (PE) and phosphoglycerol (PG) PLs, inspired by the composition of the inner leaflet of a bacterial outer membrane. Using the natural oil squalene as the continuous organic phase, no additional emulsion stabilizer is needed. On the other hand, a small amount of Span 80 is required when dodecane is used. The obtained nanoemulsions are stable for at least two hours, thus allowing the droplet size and distribution to be characterized by Dynamic Light Scattering (DLS) and the lipid layer structure and dynamics to be analyzed by Electron Paramagnetic Resonance (EPR) spectroscopy. The results indicate that squalene shallowly intercalates among the lipid tail termini, being unable to deeply penetrate the adsorbed lipid monolayer. The altered lipid dynamics are proposed to be the reason for the enhanced emulsion stability, this paving the way to future implementations and possible applications. Full article

(This article belongs to the Special Issue Micro/Nano Emulsions: Smart Colloids for Multiple Applications)

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6 pages, 2349 KiB

Open AccessArticle

Interfacial and Bulk Stabilization of Oil/Water System: A Novel Synergistic Approach

by Ahmad Shakeel, Ujala Farooq and Claire Chassagne

Nanomaterials 2020, 10(2), 356; https://doi.org/10.3390/nano10020356 - 18 Feb 2020

Cited by 16 | Viewed by 2989

Abstract

Oil/water emulsions are usually stabilized either by interfacial modification using nanoparticles and surfactants (stated as pickering emulsion or bijels) or by bulk stabilization with the help of low-molecular-weight or polymeric gelators (known as bigels) in response to some external stimuli (e.g., pH, temperature). [...] Read more.

Oil/water emulsions are usually stabilized either by interfacial modification using nanoparticles and surfactants (stated as pickering emulsion or bijels) or by bulk stabilization with the help of low-molecular-weight or polymeric gelators (known as bigels) in response to some external stimuli (e.g., pH, temperature). Both these approaches result in different systems that are quite useful for different applications, including catalysis, pharmaceutical and agrochemicals. However, these systems also possess some inherent drawbacks that need to be addressed, like difficulty in fabrication and ensuring the permanent binding of nanoparticles at the oil/water interface, in case of nanoparticles stabilized emulsions (i.e., interfacial stabilization). Similarly, the long-term stability of the oil/water systems produced by using (hydro/organo) gelators (i.e., bulk stabilization) is a major concern. Here, we show that the oil/water system with improved mechanical and structural properties can be prepared with the synergistic effect of interfacial and bulk stabilization. We achieve this by using nanoparticles to stabilize the oil/water interface and polymeric gelators to stabilize the bulk phases (oil and water). Furthermore, the proposed strategy is extremely adaptable, as the properties of the resultant system can be finely tuned by manipulating different parameters such as nanoparticles content and their surface functionalization, solvent type and its volume fraction, and type and amount of polymeric gelators. Full article

(This article belongs to the Special Issue Micro/Nano Emulsions: Smart Colloids for Multiple Applications)

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15 pages, 2766 KiB

Open AccessArticle

Two-Dimensional Clusters of Colloidal Particles Induced by Emulsion Droplet Evaporation

by Hai Pham-Van, Linh Tran-Phan-Thuy, Cuong Tran-Manh, Bich Do-Danh and Hoang Luc-Huy

Nanomaterials 2020, 10(1), 156; https://doi.org/10.3390/nano10010156 - 16 Jan 2020

Cited by 6 | Viewed by 2969

Abstract

The minimization principle of the second moment of the mass distribution (

M_{2}

) is responsible for the unique structure of three-dimensional clusters by using emulsion droplet evaporation. Herein we study the structure of two-dimensional clusters of colloidal particles bound at the [...] Read more.

The minimization principle of the second moment of the mass distribution (

M_{2}

) is responsible for the unique structure of three-dimensional clusters by using emulsion droplet evaporation. Herein we study the structure of two-dimensional clusters of colloidal particles bound at the interface of liquid droplets in the plane. We found that, differently from the three-dimensional system, the two-dimensional clusters have multiple degenerate configurations (isomers). An interesting feature of such two-dimensional clusters is that they have the same packings as those belonging to a class of geometric figures known as polyiamonds. In particular, except for the six-particle cluster, many higher order clusters of polyiamond have not been reported previously. Using a simple geometrical approach, based on the number of ways to generate a packing, we calculated the occupation probabilities of distinct isomeric clusters. The level of agreement with the results of metropolis Monte Carlo simulations was good for clusters containing up to nine particles, suggesting that our two-dimensional cluster structures are not a result of the minimization of the second moment. In addition, the structure of these clusters is somewhat insensitive to the range and depth of the interparticle potential, in good agreement with the results in the literature. Full article

(This article belongs to the Special Issue Micro/Nano Emulsions: Smart Colloids for Multiple Applications)

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Review

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43 pages, 2820 KiB

Open AccessReview

Foray into Concepts of Design and Evaluation of Microemulsions as a Modern Approach for Topical Applications in Acne Pathology

by Marina-Theodora Talianu, Cristina-Elena Dinu-Pîrvu, Mihaela Violeta Ghica, Valentina Anuţa, Viorel Jinga and Lăcrămioara Popa

Nanomaterials 2020, 10(11), 2292; https://doi.org/10.3390/nano10112292 - 19 Nov 2020

Cited by 10 | Viewed by 3893

Abstract

With a fascinating complexity, governed by multiple physiological processes, the skin is considered a mantle with protective functions which during lifetime are frequently impaired, triggering dermatologic disorders. As one of the most prevalent dermatologic conditions worldwide, characterized by a complex pathogenesis and a [...] Read more.

With a fascinating complexity, governed by multiple physiological processes, the skin is considered a mantle with protective functions which during lifetime are frequently impaired, triggering dermatologic disorders. As one of the most prevalent dermatologic conditions worldwide, characterized by a complex pathogenesis and a high recurrence, acne can affect the patient’s quality of life. Smart topical vehicles represent a good option in the treatment of a versatile skin condition. By surpassing the stratum corneum known for diffusional resistance, a superior topical bioavailability can be obtained at the affected place. In this direction, the literature study presents microemulsions as a part of a condensed group of modern formulations. Microemulsions are appreciated for their superior profile in matters of drug delivery, especially for challenging substances with hydrophilic or lipophilic structures. Formulated as transparent and thermodynamically stable systems, using simplified methods of preparation, microemulsions have a simple and clear appearance. Their unique structures can be explained as a function of the formulation parameters which were found to be the mainstay of a targeted therapy. Full article

(This article belongs to the Special Issue Micro/Nano Emulsions: Smart Colloids for Multiple Applications)

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40 pages, 4891 KiB

Open AccessFeature PaperReview

Microemulsion Microstructure(s): A Tutorial Review

by Giuseppe Tartaro, Helena Mateos, Davide Schirone, Ruggero Angelico and Gerardo Palazzo

Nanomaterials 2020, 10(9), 1657; https://doi.org/10.3390/nano10091657 - 24 Aug 2020

Cited by 116 | Viewed by 10757

Abstract

Microemulsions are thermodynamically stable, transparent, isotropic single-phase mixtures of two immiscible liquids stabilized by surfactants (and possibly other compounds). The assortment of very different microstructures behind such a univocal macroscopic definition is presented together with the experimental approaches to their determination. This tutorial [...] Read more.

Microemulsions are thermodynamically stable, transparent, isotropic single-phase mixtures of two immiscible liquids stabilized by surfactants (and possibly other compounds). The assortment of very different microstructures behind such a univocal macroscopic definition is presented together with the experimental approaches to their determination. This tutorial review includes a necessary overview of the microemulsion phase behavior including the effect of temperature and salinity and of the features of living polymerlike micelles and living networks. Once these key learning points have been acquired, the different theoretical models proposed to rationalize the microemulsion microstructures are reviewed. The focus is on the use of these models as a rationale for the formulation of microemulsions with suitable features. Finally, current achievements and challenges of the use of microemulsions are reviewed. Full article

(This article belongs to the Special Issue Micro/Nano Emulsions: Smart Colloids for Multiple Applications)

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26 pages, 2583 KiB

Open AccessReview

Synthesis and Technology of Nanoemulsion-Based Pesticide Formulation

by Isshadiba Faikah Mustafa and Mohd Zobir Hussein

Nanomaterials 2020, 10(8), 1608; https://doi.org/10.3390/nano10081608 - 17 Aug 2020

Cited by 115 | Viewed by 13886

Abstract

Declines in crop yield due to pests and diseases require the development of safe, green and eco-friendly pesticide formulations. A major problem faced by the agricultural industry is the use of conventional agrochemicals that contribute broad-spectrum effects towards the environment and organisms. As [...] Read more.

Declines in crop yield due to pests and diseases require the development of safe, green and eco-friendly pesticide formulations. A major problem faced by the agricultural industry is the use of conventional agrochemicals that contribute broad-spectrum effects towards the environment and organisms. As a result of this issue, researchers are currently developing various pesticide formulations using different nanotechnology approaches. The progress and opportunities in developing nanoemulsions as carriers for plant protection or nanodelivery systems for agrochemicals in agricultural practice have been the subject of intense research. New unique chemical and biologic properties have resulted in a promising pesticide nanoformulations for crop protection. These innovations—particularly the nanoemulsion-based agrochemicals—are capable of enhancing the solubility of active ingredients, improving agrochemical bioavailability, and improving stability and wettability properties during the application, thus resulting in better efficacy for pest control and treatment. All of these—together with various preparation methods towards a greener and environmentally friendly agrochemicals—are also discussed and summarized in this review. Full article

(This article belongs to the Special Issue Micro/Nano Emulsions: Smart Colloids for Multiple Applications)

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17 pages, 1022 KiB

Open AccessReview

The Role of Additives in Warm Mix Asphalt Technology: An Insight into Their Mechanisms of Improving an Emerging Technology

by Paolino Caputo, Abraham A. Abe, Valeria Loise, Michele Porto, Pietro Calandra, Ruggero Angelico and Cesare Oliviero Rossi

Nanomaterials 2020, 10(6), 1202; https://doi.org/10.3390/nano10061202 - 19 Jun 2020

Cited by 65 | Viewed by 4922

Abstract

The asphalt industry’s incentive to reduce greenhouse gas emissions has increased since the 1990s due to growing concerns on environmental issues such as global warming and carbon footprint. This has stimulated the introduction of Warm Mix Asphalt (WMA) and its technologies which serve [...] Read more.

The asphalt industry’s incentive to reduce greenhouse gas emissions has increased since the 1990s due to growing concerns on environmental issues such as global warming and carbon footprint. This has stimulated the introduction of Warm Mix Asphalt (WMA) and its technologies which serve the purpose of reducing greenhouse gas emissions by reducing the mixing and compaction temperatures of asphalt mix. WMA gained popularity due to the environmental benefit it offers without compromising the properties, performance and quality of the asphalt mix. WMA is produced at significantly lower temperatures (slightly above 100 °C) and thus results in less energy consumption, fewer emissions, reduced ageing, lower mixing and compaction temperatures, cool weather paving and better workability of the mix. The latter of these benefits is attributed to the incorporation of additives into WMA. These additives can also confer even better performance of WMA in comparison to conventional Hot Mix Asphalt (HMA) methods. Even though there are recommended dosages of several WMA additives, there is no general standardized mixture design procedure and this makes it challenging to characterize the mechanism(s) of action of these additives in the warm mix. The effects of the addition of additives into WMA are known to a reasonable extent but not so much is known about the underlying interactions and phenomena which bring about the mechanism(s) by which these additives confer beneficial features into the warm mix. Additives in a certain way are being used to bridge the gap and minimize or even nullify the effect of the mixing temperature deficit involved in WMA processes while improving the general properties of the mix. This review presents WMA technologies such as wax, chemical additives and foaming processes and the mechanisms by which they function to confer desired characteristics and improve the durability of the mix. Hybrid techniques are also briefly mentioned in this paper in addition to a detailed description of the specific modes of action of popular WMA technologies such as Sasobit, Evotherm and Advera. This paper highlights the environmental and technical advantages of WMA over the conventional HMA methods and also comprehensively analyzes the mechanism(s) of action of additives in conferring desirable characteristics on WMA, which ultimately improves its durability. Full article

(This article belongs to the Special Issue Micro/Nano Emulsions: Smart Colloids for Multiple Applications)

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