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Zhu X, Li K, Li J, Peng L. Physicochemical properties and antibacterial property of pickering emulsion stabilized by smart Janus nanospheres. Food Chem 2024; 451:139413. [PMID: 38663237 DOI: 10.1016/j.foodchem.2024.139413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 04/12/2024] [Accepted: 04/16/2024] [Indexed: 05/26/2024]
Abstract
In this study, responsive Janus nanospheres were prepared by grafting LMA and DMAEMA monomers on both sides of SiO2 nanospheres using the Pickering emulsion stencil method and RAFT polymerization. The successful synthesis was verified through infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), scanning electron microscopy (SEM) characterizations. Subsequently, Pickering emulsion was formulated using Janus nanospheres as emulsifiers. The particle size of the emulsion droplets was systematically investigated by manipulating factors such as pH, nanosphere dosage, water to oil ratio, and oil phase polarity. Notably, the Pickering emulsion exhibited responsive properties to pH, temperature, and CO2. Furthermore, Janus nanospheres exhibited excellent emulsification property for real oil phases, including canola oil, kerosene, gasoline, and diesel oil. Building upon this, a smart antibacterial Pickering emulsion was developed using Janus nanospheres, and its inhibition rate against E. coli could reach 100% within 4 h, which would be beneficial for its application in the food field.
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Affiliation(s)
- Xiaoping Zhu
- College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, PR China
| | - Keran Li
- College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, PR China; State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610500, PR China.
| | - Jing Li
- College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, PR China
| | - Lifei Peng
- College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500, PR China
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Barilyuk DV, Korol AA, Chikanova ES, Lomakina MA, Shtansky DV. Highly Hydrophilic TiO 2 Nanoparticles as Stabilizers of Pickering Emulsions with Photosensitive Lipophilic Compounds: Synthesis and Application. J Phys Chem B 2024; 128:7903-7911. [PMID: 39096291 DOI: 10.1021/acs.jpcb.4c03315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/05/2024]
Abstract
Pickering emulsions are a very promising system for encapsulating and photoprotecting active ingredients. The highest photoprotection efficiency can be achieved when bare TiO2 nanoparticles are used as stabilizers. However, the main problem when using highly hydrophilic TiO2 nanoparticles is their inability to adsorb at the oil-water interface. Here, we developed emulsions stabilized by bare, highly hydrophilic TiO2 nanoparticles for the encapsulation and photoprotection of active lipophilic compounds. Emulsion stabilization occurs due to the formation of hydrogen bonds between hydroxyl groups on the particle surface and the carbonyl groups of the oil molecules. The stability and rheological properties of emulsions are explained by the properties of the initial hydrosols. The resulting Pickering emulsions demonstrated effective UV protection of α-lipoic acid. Our results pave the way for the formulation of Pickering emulsions with a widely used cosmetic oil and show for the first time the possibility of photoprotection of a lipophilic active substance using unmodified TiO2 nanoparticles.
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Affiliation(s)
- Danil V Barilyuk
- National University of Science and Technology "MISIS", Leninsky prospect 4, Moscow 119049, Russia
| | - Artem A Korol
- National University of Science and Technology "MISIS", Leninsky prospect 4, Moscow 119049, Russia
| | - Ekaterina S Chikanova
- National University of Science and Technology "MISIS", Leninsky prospect 4, Moscow 119049, Russia
| | - Maria A Lomakina
- Chemistry Department, M.V. Lomonosov Moscow State University, Leninskiye Gory, 1/3, Moscow 119991, Russia
| | - Dmitry V Shtansky
- National University of Science and Technology "MISIS", Leninsky prospect 4, Moscow 119049, Russia
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Yu J, Shang Q, Zhang M, Hu L, Jia P, Zhou Y. Tung oil-based waterborne UV-curable coatings via cellulose nanofibril stabilized Pickering emulsions for self-healing and anticorrosion application. Int J Biol Macromol 2024; 256:128114. [PMID: 37979750 DOI: 10.1016/j.ijbiomac.2023.128114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 11/10/2023] [Accepted: 11/14/2023] [Indexed: 11/20/2023]
Abstract
In this study, waterborne UV-curable coatings with self-healing properties based on transesterification were prepared using renewable biomass resources for anti-corrosion application. Tung oil (TO)-based oligomer (TMHT) was synthesized through Diels-Alder reaction of TO with maleic anhydride, subsequent ring opening reaction with hydroxyethyl acrylate (HEA), and final neutralize reaction with triethylamine. A series of waterborne UV-curable coatings were prepared from cellulose nanofibrils (CNF) stabilized TMHT-based Pickering emulsions after drying and UV light-curing processes. It is suggested that CNF significantly improved the storage stability of Pickering emulsions. The obtained waterborne UV-curable coatings with CNF of 1-3 wt% exhibited remarking coating and mechanical performance (pencil hardness up to 5 H, adhesion up to 2 grade, flexibility of 2 mm, tensile strength up to 11.6 MPa, etc.), great transmittance (82.3 %-80.8 %) and great corrosion resistance (|Z|0.01Hz up to 5.4 × 106 Ω·cm2). Because of the presence of the dynamic ester bonds in TMHT, the coatings exhibited excellent self-healing performance (78.05 %-56.34 %) at 150 °C without catalyst and external force. More importantly, the |Z|0.01Hz of the self-healing coating was higher than that of the scratched coating, indicating that the self-healing performance could extend the service life of the coating in corrosion resistant application.
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Affiliation(s)
- Jinni Yu
- Institute of Chemical Industry of Forest Products, CAF; Key Lab. of Biomass Energy and Material, No 16, Suojin Wucun, Nanjing 210042, Jiangsu Province, China; Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, 159 Longpan Road, Nanjing 210037, Jiangsu Province, China
| | - Qianqian Shang
- Institute of Chemical Industry of Forest Products, CAF; Key Lab. of Biomass Energy and Material, No 16, Suojin Wucun, Nanjing 210042, Jiangsu Province, China; Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, 159 Longpan Road, Nanjing 210037, Jiangsu Province, China.
| | - Meng Zhang
- Institute of Chemical Industry of Forest Products, CAF; Key Lab. of Biomass Energy and Material, No 16, Suojin Wucun, Nanjing 210042, Jiangsu Province, China; Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, 159 Longpan Road, Nanjing 210037, Jiangsu Province, China
| | - Lihong Hu
- Institute of Chemical Industry of Forest Products, CAF; Key Lab. of Biomass Energy and Material, No 16, Suojin Wucun, Nanjing 210042, Jiangsu Province, China; Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, 159 Longpan Road, Nanjing 210037, Jiangsu Province, China
| | - Puyou Jia
- Institute of Chemical Industry of Forest Products, CAF; Key Lab. of Biomass Energy and Material, No 16, Suojin Wucun, Nanjing 210042, Jiangsu Province, China; Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, 159 Longpan Road, Nanjing 210037, Jiangsu Province, China.
| | - Yonghong Zhou
- Institute of Chemical Industry of Forest Products, CAF; Key Lab. of Biomass Energy and Material, No 16, Suojin Wucun, Nanjing 210042, Jiangsu Province, China; Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, 159 Longpan Road, Nanjing 210037, Jiangsu Province, China
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Ma Q, Nie C, Bu X, Liu B, Li W, Zhang X, Tan Y, Wu P, Fan G, Wang J. Properties of Pickering emulsions stabilized by cellulose nanocrystals extracted from litchi peels. Int J Biol Macromol 2023; 242:124879. [PMID: 37192711 DOI: 10.1016/j.ijbiomac.2023.124879] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/04/2023] [Accepted: 05/11/2023] [Indexed: 05/18/2023]
Abstract
The development of Pickering emulsions which are applicable to the food industry still remains challenges due to the limited availability for biocompatible, edible and natural emulsifiers. The purpose of this study was to extract cellulose nanocrystals from litchi peels (LP-CNCs), and evaluate their emulsifying properties. The results showed that the LP-CNCs were needle-like and they possessed high crystallinity (72.34 %) and aspect ratio. When the concentrations of LP-CNCs were >0.7 wt% or the contents of oil were no >0.5, stable Pickering emulsions were obtained. The microstructures of emulsions confirmed that LP-CNCs formed dense interfacial layers on the surface of oil droplets, which functioned as barriers to prevent aggregation and flocculation among droplets. Rheological results showed that the emulsions exhibited typical shear thinning behavior. The elastic of emulsions was dominant, and their gel strength could be enhanced by regulating the contents of emulsifiers or oil. Additionally, the Pickering emulsions stabilized by LP-CNCs showed extremely high pH, ionic strength, and temperature tolerance. This strategy provides an innovative alternative to tackle the dilemma of preparing highly stable Pickering emulsions using natural particles in food products.
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Affiliation(s)
- Qin Ma
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Chunling Nie
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Xianpan Bu
- Ankang R&D Center for Se-enriched Products, Ankang, Shaanxi 725000, China
| | - Bingqian Liu
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Weilong Li
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Xiaowan Zhang
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Yinfeng Tan
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Pengrui Wu
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, Shaanxi, China
| | - Guangsen Fan
- School of Food and Health, Beijing Technology & Business University (BTBU), Beijing 100048, China.
| | - Jianguo Wang
- College of Food Science and Engineering, Northwest A&F University, Yangling 712100, Shaanxi, China.
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Cionti C, Vavassori G, Pargoletti E, Meroni D, Cappelletti G. One-step, highly stable Pickering emulsions stabilized by ZnO: tuning emulsion stability by in situ functionalization. J Colloid Interface Sci 2022; 628:82-89. [PMID: 35908434 DOI: 10.1016/j.jcis.2022.07.129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 07/18/2022] [Accepted: 07/20/2022] [Indexed: 11/15/2022]
Abstract
HYPOTHESIS Oxide-stabilized emulsions generally require a surface functionalization step to tune the oxide wettability, often involving hazardous hydrophobizing agents. Here, we propose the in situ functionalization of ZnO in vegetable oils without the addition of any modifier, resulting in the one-step formation of highly stable Pickering emulsions. EXPERIMENTS The role of ZnO surface features was studied by modifying the particles' wettability through surface functionalization and by comparing different oil phases. The emulsion stability was assessed through aging tests, multiple hot-and-cold cycles, centrifugation, and addition of multiple electrolytes. FINDINGS While the wetting features of the functionalized oxide play a crucial role when the oil phase is methyl octanoate, emulsions based on vegetable oils form also using hydrophilic ZnO. During the emulsification, an in situ functionalization of bare ZnO particles takes place due to the fatty acids present in vegetable oil. These in situ-generated systems lead to stable emulsions showing < 2 μm-diameter oil droplets. The resulting emulsions display excellent stability over time (over seven months) and against temperature variations, mechanical stress and increased ionic strength. Finally, we demonstrate that this approach can be extended to a variety of vegetable oils and oxides with different morphologies.
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Affiliation(s)
- Carolina Cionti
- Department of Chemistry, Università degli Studi di Milano, via Golgi 19, Milano 20133, Italy; Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), via Giusti 9, Florence 50121, Italy
| | - Giovanni Vavassori
- Department of Chemistry, Università degli Studi di Milano, via Golgi 19, Milano 20133, Italy
| | - Eleonora Pargoletti
- Department of Chemistry, Università degli Studi di Milano, via Golgi 19, Milano 20133, Italy; Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), via Giusti 9, Florence 50121, Italy
| | - Daniela Meroni
- Department of Chemistry, Università degli Studi di Milano, via Golgi 19, Milano 20133, Italy; Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), via Giusti 9, Florence 50121, Italy.
| | - Giuseppe Cappelletti
- Department of Chemistry, Università degli Studi di Milano, via Golgi 19, Milano 20133, Italy; Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), via Giusti 9, Florence 50121, Italy.
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Chen K, Zhou X, Wang D, Li J, Qi D. Synthesis and characterization of a broad-spectrum TiO2@lignin UV-protection agent with high antioxidant and emulsifying activity. Int J Biol Macromol 2022; 218:33-43. [DOI: 10.1016/j.ijbiomac.2022.06.190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 06/08/2022] [Accepted: 06/28/2022] [Indexed: 01/08/2023]
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Effect of surface functionalized silica nanoparticles on interfacial behavior: Wettability, interfacial tension and emulsification characteristics. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118220] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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8
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Fresco-Cala B, Cárdenas S. Advanced polymeric solids containing nano- and micro-particles prepared via emulsion-based polymerization approaches. A review. Anal Chim Acta 2022; 1208:339669. [DOI: 10.1016/j.aca.2022.339669] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 02/26/2022] [Accepted: 02/28/2022] [Indexed: 12/11/2022]
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Effect of Fe3O4/CNC ratio on properties of olive oil-in-water Pickering emulsions. Colloid Polym Sci 2022. [DOI: 10.1007/s00396-021-04938-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Sun Y, Tang W, Pu C, Li R, Sun Q, Wang H. Improved stability of liposome-stabilized emulsions as coencapsulation delivery system for vitamin B2, vitamin E and β-carotene. Food Funct 2022; 13:2966-2984. [DOI: 10.1039/d1fo03617c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To realize the co-encapsulation of multiple nutraceuticals with different solubilities, Pickering emulsions stabilized by freshly-prepared liposome suspension stabilized emulsion (Fre-Lip-Sus-E) and hydrated lyophilized liposome stabilized emulsion (Hyd-Lyo-Lip-E) were prepared, in...
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Barison S, Cabaleiro D, Rossi S, Kovtun A, Melucci M, Agresti F. Paraffin–graphene oxide hybrid nano emulsions for thermal management systems. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127132] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Fapojuwo DP, Oseghale CO, Akinnawo CA, Meijboom R. Bimetallic PdM (M = Co, Ni) catalyzed hydrogenation of nitrobenzene at the water/oil interface in a Pickering emulsion. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.126513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Liu L, Pu X, Tao H, Chen K, Guo W, Luo D, Ren Z. Pickering emulsion stabilized by organoclay and intermediately hydrophobic nanosilica for high-temperature conditions. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2020.125694] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Wang J, Sun Y, Yu M, Lu X, Komarneni S, Yang C. Emulsions stabilized by highly hydrophilic TiO 2 nanoparticles via van der Waals attraction. J Colloid Interface Sci 2021; 589:378-387. [PMID: 33482535 DOI: 10.1016/j.jcis.2021.01.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 12/16/2020] [Accepted: 01/05/2021] [Indexed: 10/22/2022]
Abstract
HYPOTHESIS Highly hydrophilic nanoparticles are generally considered not suitable for stabilizing Pickering emulsions, since they could not be effectively wetted by the oil phase at the water-oil interface. However, highly hydrophilic nanoparticles with good dispersity are possibly absorbed and packed onto the surface of the oil droplets in water via the van der Waals attraction between the nanoparticles and the oil droplets. Hence, a novel "van der Waals emulsion" should be possible to be stabilized by highly hydrophilic nanoparticles. EXPERIMENTS Oil-in-water emulsions solely stabilized by pristine TiO2 nanoparticles (i.e., TiO2 without any modification or additives) were prepared. The emulsification behavior under varying pH value, oil fraction, particle content and temperature of the emulsion were explored. Composite wax-based beads which encapsulated chemical sunscreen and was coated by TiO2 nanoparticles, was also fabricated using the obtained emulsion as the templates. FINDINGS The emulsions displayed the highest stability near the isoelectric points of the TiO2 nanoparticles, which was attributed to the van der Waals attraction between TiO2 nanoparticles and oil droplets. Such mechanism was supported by a theoretical analysis based on calculation of the Hamaker constants and experimental evidences. Therefore, this work presents a simple, general and green method for preparing particle-stabilized emulsions.
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Affiliation(s)
- Jing Wang
- Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China
| | - Yajuan Sun
- Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China.
| | - Mingying Yu
- Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China
| | - Xihua Lu
- College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China
| | - Sridhar Komarneni
- Department of Ecosystem Science and Management and Materials Research Institute, 204 Energy and the Environment Laboratory, The Pennsylvania State University, University Park, PA 16802, USA.
| | - Cheng Yang
- Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China.
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The hydration effect of singly charged ions on the electrosurface properties of titanium dioxide aqueous suspensions. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2020.125005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Chen L, Ao F, Ge X, Shen W. Food-Grade Pickering Emulsions: Preparation, Stabilization and Applications. Molecules 2020; 25:E3202. [PMID: 32674301 PMCID: PMC7397194 DOI: 10.3390/molecules25143202] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/10/2020] [Accepted: 07/11/2020] [Indexed: 01/14/2023] Open
Abstract
In recent years, Pickering emulsions have emerged as a new method and have attracted much attention in the fields of food sciences. Unlike conventional emulsions, Pickering emulsions are stabilized by solid particles, which can irreversibly adsorb on the oil-water interface to form a dense film to prevent the aggregation of droplets. The research and development of food-grade solid particles are increasingly favored by scientific researchers. Compared with conventional emulsions, Pickering emulsions have many advantages, such as fewer using amounts of emulsifiers, biocompatibility and higher safety, which may offer feasibility to have broad application prospects in a wide range of fields. In this article, we review the preparation methods, stabilization mechanism, degradation of Pickering emulsions. We also summarize its applications in food sciences in recent years and discuss its future prospects and challenges in this work.
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Affiliation(s)
- Lijuan Chen
- Department of Food Science and Technology, College of Light Industry Science and Engineering, Nanjing Forestry University, Nanjing 210037, China;
| | - Fen Ao
- School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi’an 710000, China;
| | - Xuemei Ge
- Department of Food Science and Technology, College of Light Industry Science and Engineering, Nanjing Forestry University, Nanjing 210037, China;
| | - Wen Shen
- School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi’an 710000, China;
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Sadgar AL, Deore TS, Jayaram RV. Pickering Interfacial Catalysis-Knoevenagel Condensation in Magnesium Oxide-Stabilized Pickering Emulsion. ACS OMEGA 2020; 5:12224-12235. [PMID: 32548405 PMCID: PMC7271354 DOI: 10.1021/acsomega.0c00819] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 05/07/2020] [Indexed: 06/01/2023]
Abstract
In the present study, a novel catalytic route for the Knoevenagel condensation reaction has been developed by Pickering interfacial catalysis using magnesium oxide (MgO) as both an emulsion stabilizer and a base catalyst. MgO was prepared by the precipitation method using sodium hydroxide or ammonium hydroxide as the precipitating agent and calcined at different temperatures. The calcined samples were characterized by XRD, SEM, TEM, AFM, BET, and DLS techniques. The catalytic application of the emulsions stabilized by MgO was investigated for the Knoevenagel condensation reaction of benzaldehyde and its derivatives with malononitrile. All of the reactions were carried out at an ambient temperature (30 °C) under static conditions without stirring. Both the emulsion-stabilizing ability and the catalytic activity of MgO were found to be affected by the method of preparation, calcination temperature, and the nature of the oil phase. It was observed that the method of preparation varied the texture and morphology of MgO and thus the stability and droplet size of the emulsion formed. This was further reflected in the catalytic activity. The highest yield (87%) of the condensation product was obtained with MgO prepared by precipitation using a strong base (NaOH) and further calcined at 400 °C. The developed catalytic system offers several green chemistry advantages such as reusable solid-base catalyst and use of a single material as both emulsion stabilizer and catalyst. Room-temperature reaction under static conditions is an additional advantage of the developed catalytic system.
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Liu L, Pu X, Zhou Y, Zhou J, Luo D, Ren Z. Smart Pickering water-in-oil emulsion by manipulating interactions between nanoparticles and surfactant as potential oil-based drilling fluid. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2019.124246] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Kataruka A, Hutchens SB. PDMS polymerized high internal phase emulsions (polyHIPEs) with closed-cell, aqueous-filled microcavities. SOFT MATTER 2019; 15:9665-9675. [PMID: 31728471 DOI: 10.1039/c9sm01732a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Emulsion templates can produce a wide range of unique microstructures via solidification of the continuous phase. Some of these structures result in unique, fluid-filled composites reminiscent of biological tissue when the templating droplets develop into closed-cell structures. However, the state-of-the-art falls short in replicating the mechanical and functional response of biological structures due to stiff, fragile, and bio-incompatible materials while lacking systematic processing parameters. This article describes the synthesis of high internal phase, closed-cell, polydimethylsiloxane (PDMS) elastomeric foams which simultaneously achieve biocompatibility, mechanical robustness, flexibility, and selective permeability. Water-in-oil high internal phase emulsions (HIPEs) stabilized by silica nano-particles (SNPs) provide the microstructural template, resulting in a >74% by volume aqueous phase (up to 82%). To overcome the prohibitive barrier to HIPE formation when using a mechanically-superior, but highly viscous commercial PDMS kit, we produce HIPE templates via centrifugation of low internal phase emulsions (LIPEs, <30% by volume dispersed phase). This oil phase crosslinks into an aqueous-filled (water + glycerol + NaCl) elastomeric composite. The composite's microstructural dependence on viscosity ratio, mixing speed, emulsifier concentration, and centrifugal force are systematically characterized. The resulting microstructured, fluid-filled elastomer composites exhibit mechanically robust and highly flexible behavior due to the excellent properties of the PDMS continuous phase.
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