Micro/Nano Emulsions: Fabrication and Applications

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Synthesis, Interfaces and Nanostructures".

Deadline for manuscript submissions: closed (30 November 2023) | Viewed by 11154

Special Issue Editors


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Guest Editor
Department of Chemical and Environmental Engineering, University of Oviedo, Oviedo, Spain
Interests: emulsions; emulsification techniques; encapsulation; hydrophobicity; colloidal vesicles; colloidal complexes; novel emulsifiers; physicochemical stability
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Chemical and Environmental Engineering, University of Oviedo, Oviedo, Spain
Interests: surfactants; contact angle; surface tension; emulsions; colloid chemistry; colloid dispersion; dynamic light scattering; particle size analysis; rheology; colloids
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue aims to describe the techniques essential to producing microemulsions and nanoemulsions, taking into account novel formulations and novel preparation methods.

Articles submitted for publication in this Special Issue should be focused on microemulsion and nanoemulsion applications, such as drug delivery, encapsulation, and the synthesis of nanoparticles/nanostructured materials. We also welcome articles on preparation methods, innovative formulations, and the characterization of emulsions.

Articles could describe different formulations, such as formulations stabilized with surfactants, polymers, proteins, or other food-based particles, being of special interest those that allow for the droplet size and the droplet size distribution to be controlled or those with a low energy requirement.

Moreover, we welcome articles that describe any novel emulsion formulation regarding the final application or the use of novel grade stabilizers.

Prof. Dr. Gemma Gutierrez
Prof. Dr. Maria Matos
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • microemulsions
  • nanoencapsulation
  • particle formation
  • drug delivery
  • nanoemulsions
  • hydrophobicity

Published Papers (6 papers)

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Research

16 pages, 2793 KiB  
Article
A Cocktail-Based Formula for the Design of Nanosized Cosmeceuticals as Skincare and Anti-Age Products
by Ines Castangia, Federica Fulgheri, Matteo Perra, Gianluigi Bacchetta, Laura Fancello, Francesco Corrias, Iris Usach, Josè Esteban Peris, Maria Letizia Manca and Maria Manconi
Nanomaterials 2023, 13(17), 2485; https://0-doi-org.brum.beds.ac.uk/10.3390/nano13172485 - 04 Sep 2023
Viewed by 1230
Abstract
Nasco and Bovale grape pomace extracts, alone or in association, were loaded in nanoemulsions tailored for cosmetic application, using Kolliphor®RH40 (kolliphor) as the synthetic surfactant, Olivem®1000 (olivem) as the natural one, and lecithin as the cosurfactant. Pink transparent or [...] Read more.
Nasco and Bovale grape pomace extracts, alone or in association, were loaded in nanoemulsions tailored for cosmetic application, using Kolliphor®RH40 (kolliphor) as the synthetic surfactant, Olivem®1000 (olivem) as the natural one, and lecithin as the cosurfactant. Pink transparent or milky dispersions, as a function of the used extract and surfactant, were obtained to be used as cosmeceutical serum or milk. The sizes of the nanoemulsion droplets were small (≈77 nm with kolliphor and ≈141 nm with olivem), homogenously dispersed (~0.24 with kolliphor and ~0.16 with olivem), highly negatively charged (≈−43 mV irrespective of the used surfactant) and their stability either on storage or under stressing conditions was affected by the used extract and surfactant. Formulations protected the extracts from the degradation caused by UV exposition, were biocompatible against keratinocytes, protected them against oxidative damages induced using hydrogen peroxide and inhibited the release of nitrite induced in macrophages using the lipopolysaccharide inflammatory stimulus. The overall results underlined the key role played by the composition of the formula to achieve a suitable cosmeceutical for skin care but even for the prevention of premature aging and chronic damages caused by the stressing conditions. Full article
(This article belongs to the Special Issue Micro/Nano Emulsions: Fabrication and Applications)
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23 pages, 5403 KiB  
Article
Novel Microemulsions with Essential Oils for Environmentally Friendly Cleaning of Copper Cultural Heritage Artifacts
by Mihaela Ioan, Dan Florin Anghel, Ioana Catalina Gifu, Elvira Alexandrescu, Cristian Petcu, Lia Mara Diţu, Georgiana Alexandra Sanda, Daniela Bala and Ludmila Otilia Cinteza
Nanomaterials 2023, 13(17), 2430; https://0-doi-org.brum.beds.ac.uk/10.3390/nano13172430 - 26 Aug 2023
Cited by 1 | Viewed by 2048
Abstract
Cleaning represents an important and challenging operation in the conservation of cultural heritage, and at present, a key issue consists in the development of more sustainable, “green” materials and methods to perform it. In the present work, a novel xylene-in-water microemulsion based on [...] Read more.
Cleaning represents an important and challenging operation in the conservation of cultural heritage, and at present, a key issue consists in the development of more sustainable, “green” materials and methods to perform it. In the present work, a novel xylene-in-water microemulsion based on nonionic surfactants with low toxicity was obtained, designed as low-impact cleaning agent for metallic historic objects. Phase diagram of the mixtures containing polyoxyethylene-polyoxypropilene triblock copolymer Pluronic P84 and D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) as surfactants, water, ethanol and xylene was studied, and a microemulsion with low surfactant content was selected as suitable cleaning nanosystem. Essential oils (EOs) from thyme and cinnamon leaf were added to the selected microemulsion in order to include other beneficial properties such as anticorrosive and antifungal protection. The microemulsions with or without EOs were characterized by size, size distribution and zeta potential. The cleaning efficacy of the tested microemulsions was assessed based on their ability to remove two types of artificial dirt by using X-ray energy dispersion spectrometry (EDX), scanning electron microscopy (SEM), contact angle measurements and color analysis. Microemulsions exhibit high capacity to remove artificial dirt from model copper coupons in spite of very low content of the organic solvent. Both thyme and cinnamon oil loading microemulsions prove to significantly reduce the corrosion rate of treated metallic plates compared to those of bare copper. The antifungal activity of the novel type of microemulsion was evaluated against Aspergillus niger, reported as main treat in biocorrosion of historic copper artifacts. Application of microemulsion with small amounts of EOs on Cu plates inhibits the growth of fungi, providing a good fungicidal effect. Full article
(This article belongs to the Special Issue Micro/Nano Emulsions: Fabrication and Applications)
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30 pages, 6695 KiB  
Article
Microemulsions of Nonionic Surfactant with Water and Various Homologous Esters: Preparation, Phase Transitions, Physical Property Measurements, and Application for Extraction of Tricyclic Antidepressant Drugs from Aqueous Media
by Radu C. Racovita, Maria D. Ciuca, Daniela Catana, Cezar Comanescu and Oana Ciocirlan
Nanomaterials 2023, 13(16), 2311; https://0-doi-org.brum.beds.ac.uk/10.3390/nano13162311 - 11 Aug 2023
Cited by 2 | Viewed by 1582
Abstract
Microemulsions are nanocolloidal systems composed of water, an oil, and a surfactant, sometimes with an additional co-surfactant, which have found a wide range of practical applications, including the extractive removal of contaminants from polluted water. In this study, microemulsion systems, including a nonionic [...] Read more.
Microemulsions are nanocolloidal systems composed of water, an oil, and a surfactant, sometimes with an additional co-surfactant, which have found a wide range of practical applications, including the extractive removal of contaminants from polluted water. In this study, microemulsion systems, including a nonionic surfactant (Brij 30), water, and esters selected from two homologous series of C1–C6 alkyl acetates and ethyl C1–C4 carboxylates, respectively, were prepared by the surfactant titration method. Phase transitions leading to the formation of Winsor II and Winsor IV microemulsions were observed and phase diagrams were constructed. The dependences of phase transitions on the salinity and pH and the addition of isopropanol as a co-surfactant were also investigated. Some physical properties, namely density, refractive index, electrical conductivity, dynamic viscosity, and particle size, were measured for a selection of Winsor IV microemulsions, providing further insight into some other phase transitions occurring in the monophasic domains of phase diagrams. Finally, Winsor II microemulsions were tested as extraction solvents for the removal of four tricyclic antidepressant drugs from aqueous media. Propyl acetate/Brij 30/H2O microemulsions provided the best extraction yields (>90%), the highest Nernst distribution coefficients (~40–88), and a large volumetric ratio of almost 3 between the recovered purified water and the resulting microemulsion extract. Increasing the ionic strength (salinity) or the pH of the aqueous antidepressant solutions led to an improvement in extraction efficiencies, approaching 100%. These results could be extrapolated to other classes of pharmaceutical contaminants and suggest ester- and nonionic surfactant-based microemulsions are a promising tool for environmental remediation. Full article
(This article belongs to the Special Issue Micro/Nano Emulsions: Fabrication and Applications)
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14 pages, 3398 KiB  
Article
Enhanced Emulsifying Ability of Deoxycholate through Dynamic Interaction with Layered Double Hydroxide
by Jing Xie, Kyounghyoun Lee, Hyeonjin Park, Hyun Jung and Jae-Min Oh
Nanomaterials 2023, 13(3), 567; https://0-doi-org.brum.beds.ac.uk/10.3390/nano13030567 - 30 Jan 2023
Cited by 2 | Viewed by 1714
Abstract
The emulsifying ability of the naturally occurring surfactant deoxycholic acid (DCA) was improved by dynamic interaction with nanometric layered particles, layered double hydroxide (LDH). As DCA molecules are rigid due to the facial configuration of hydrophobic–hydrophilic groups, they tend to form molecular aggregation [...] Read more.
The emulsifying ability of the naturally occurring surfactant deoxycholic acid (DCA) was improved by dynamic interaction with nanometric layered particles, layered double hydroxide (LDH). As DCA molecules are rigid due to the facial configuration of hydrophobic–hydrophilic groups, they tend to form molecular aggregation in an acidic condition or imbalanced water–lipid ratios. In this study, the homogeneous hybrids of DCA and LDH were obtained by the in situ growth of LDH at a DCA molecule. The DCA−LDH hybrid successfully prevented the molecular aggregation of DCA at an acidic pH and imbalanced water–to–oil ratio. The dynamic light scattering showed that the hydrodynamic radius of micelle in the emulsion made with DCA−LDH maintained its small size (<500 nm), while upon pH change and dilution with water, that made with DCA only uncontrollably increased up to ~3000 nm. The polydispersity index value of the DCA–LDH emulsion remained constant (<0.3) after the pH change and dilution with water, indicating the high stability of the formulation. Furthermore, time-dependent turbidity monitoring revealed that the DCA-only formulation suffered from serious coalescence and creaming compared with the DCA–LDH formulation. It is suggested that the dynamic interaction between LDH layers and DCA prevented molecular aggregation under unfavorable conditions for the oil–in–water emulsion. Full article
(This article belongs to the Special Issue Micro/Nano Emulsions: Fabrication and Applications)
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18 pages, 19877 KiB  
Article
Hypolipidemic Activity of Olive Oil-Based Nanostructured Lipid Carrier Containing Atorvastatin
by Heba S. Elsewedy, Tamer M. Shehata, Mervt M. Almostafa and Wafaa E. Soliman
Nanomaterials 2022, 12(13), 2160; https://0-doi-org.brum.beds.ac.uk/10.3390/nano12132160 - 23 Jun 2022
Cited by 4 | Viewed by 1706
Abstract
Currently, hyperlipidemia is a growing health issue that is considered a risk factor for obesity. Controlling body weight and modifying life style in most of cases are not adequate and the condition requires medical treatment. Statin drugs (mainly Atorvastatin (ATO)), have been used [...] Read more.
Currently, hyperlipidemia is a growing health issue that is considered a risk factor for obesity. Controlling body weight and modifying life style in most of cases are not adequate and the condition requires medical treatment. Statin drugs (mainly Atorvastatin (ATO)), have been used broadly and for long time as medications for handling higher levels of lipid, especially bad cholesterol, which accordingly controls the prevalence of obesity. Still, the obstacle that stands in front of any formulation is the poor solubility of the drug. Low solubility of ATO came up with poor absorption as well as poor bioavailability. This paved the way for the present study, which aimed to exploit nanotechnology and develop certain nanolipid carriers that could accommodate hydrophobic drugs, such as ATO. Nanostructured lipid carrier (NLC) containing ATO was fabricated using olive oil. Olive oil is natural plant oil possessing confirmed hypolipidemic activity that would help in improving the efficacy of the formulation. Via applying the Quality by Design (QbD) approach, one NLC formula was selected to be optimized based on appropriate size and higher entrapment. Optimized ATO-NLC was scrutinized for zeta potential, in vitro study and kinetic profile. Moreover, stability testing and in vivo hypolipidemic behavior was conducted. The optimized NLC formulation seemed to show particle size (254.23 nm) with neutral zeta potential (−1.77 mV) and entrapment efficiency (69.56%). The formulation could be prolonged for 12 h and provided higher % of release (97.17%). Stability testing confirmed the role of modifying the surface of the formulation with PEG-DSPE in providing a highly stable formulation that could withstand three months storage in two altered conditions. Ultimately, optimized ATO-NLC could successfully lower total cholesterol level in rats induced with obesity and fed a high-fat diet. Remarkably, ATO-NLC prepared with olive oil, in addition to shielding its surface, would provide a stable formulation that holds up the synergistic action between olive oil and ATO. Full article
(This article belongs to the Special Issue Micro/Nano Emulsions: Fabrication and Applications)
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12 pages, 3965 KiB  
Article
Morphological Studies of Composite Spin Crossover@SiO2 Nanoparticles
by Yue Zan, Lionel Salmon and Azzedine Bousseksou
Nanomaterials 2021, 11(12), 3169; https://0-doi-org.brum.beds.ac.uk/10.3390/nano11123169 - 23 Nov 2021
Cited by 5 | Viewed by 1693
Abstract
Spin crossover (SCO) iron (II) 1,2,4-triazole-based coordination compounds in the form of composite SCO@SiO2 nanoparticles were prepared using a reverse microemulsion technique. The thickness of the silica shell and the morphology of the as obtained core@shell nanoparticles were studied by modifying the [...] Read more.
Spin crossover (SCO) iron (II) 1,2,4-triazole-based coordination compounds in the form of composite SCO@SiO2 nanoparticles were prepared using a reverse microemulsion technique. The thickness of the silica shell and the morphology of the as obtained core@shell nanoparticles were studied by modifying the polar phase/surfactant ratio (ω), as well as the quantity and the insertion phase (organic, aqueous and micellar phases) of the tetraethylorthosilicate (TEOS) precursor, the quantity of ammonia and the reaction temperature. The morphology of the nanoparticles was monitored by transmission electron microscopy (TEM/HRTEM) while their composition probed by combined elemental analyses, thermogravimetry and EDX analyses. We report that not only the particle size can be controlled but also the size of the silica shell, allowing for interesting perspectives in post-synthetic modification of the shell. The evolution of the spin crossover properties associated with the change in morphology was investigated by variable temperature optical and magnetic measurements. Full article
(This article belongs to the Special Issue Micro/Nano Emulsions: Fabrication and Applications)
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