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Pickering emulsion

Chun-Yan Xie, Shi-Xin Meng, Long-Hui Xue, Rui-Xue Bai, Xin Yang, Yaolei Wang, Zhong-Ping Qiu, Bernard P Binks, Ting Guo, Tao Meng
Emulsion droplets can serve as ideal compartments for reactions. In fact, in many cases, the chemical reactions are supposed to be triggered at a desired position and time without change of the system environment. Here, we present a type of light and magnetic dual-responsive Pickering emulsion micro-reactor by co-adsorption of light-sensitive titania (TiO2) and super paramagnetic iron oxide (Fe3O4) nanoparticles at the oil-water interface of emulsion droplets. The droplets encapsulating different reactants in advance can be driven close to each other by an external magnetic field, and then chemical reaction is triggered by UV illumination due to the contact of the isolated reactants as a result of droplet coalescence...
November 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Hao Zhang, Sheng Xiang, Qian Luan, Yuping Bao, Qianchun Deng, Mingming Zheng, Shilin Liu, Jia Song, Hu Tang, Fenghong Huang
The aim of the present work was to study the feasibility of fabricating poly (lactic acid) (PLA) microspheres stabilized Pickering emulsions. For this purpose, the PLA microspheres were first prepared by oil-water emulsion solvent evaporation method. The effects of preparation conditions such as hydrophilic-lipophilic balance (HLB) value, emulsifier concentration, oil-water ratio and preparation temperature were evaluated by using optical microscopy. Besides, orthogonal experiments were designed to investigate the influence of preparation parameters on average diameter and uniformity, include stirring time, stirring speed, and PLA and polyvinyl alcohol (PVA) concentrations...
November 13, 2017: International Journal of Biological Macromolecules
Ji-Fen Zhang, Jiao Zhang, Fan Wang, Shuai Wang, Mei Wang, Tao Yi
A new Pickering emulsion, puerarin nanocrystalline self-stabilized Pickering emulsion (Pu-NSSPE) was developed. Box-Behnken design was used for optimizing the preparation formulation of Pu-NSSPE to improve its stability, and the effects of concentration of puerarin, volume ratio of water to oil, and pH value of water phase on the stratification index of emulsion, droplet size and drug concentration in emulsion were investigated. Results showed that the optimized Pu-NSSPE could be prepared with the concentration of puerarin of 0...
August 2017: Zhongguo Zhong Yao za Zhi, Zhongguo Zhongyao Zazhi, China Journal of Chinese Materia Medica
Thriveni G Anjali, Madivala G Basavaraj
The superior stability of Pickering emulsions can be detrimental in several applications. There is therefore growing interest in using stimuli responsive particle emulsifiers that can considerably reduce the cost of demulsification. Among the possible triggers for the remote control of emulsion stability, pH sensitive systems are advantageous because of the simplicity and ease of implementation. Herein, the destabilization mechanism of pH-switchable emulsions stabilized solely by particles of different shapes and surface properties - namely - hematite, silica and polystyrene - are discussed...
November 14, 2017: Physical Chemistry Chemical Physics: PCCP
Hang Hu, Chen Xiao, Honglian Wu, Yihui Li, Qing Zhou, Yuxiang Tang, Chan Yu, Xiangliang Yang, Zifu Li
Selective drug release is highly desirable for photothermal/chemo combination therapy when two or even more theranostic agents are encapsulated together within the same nanocarrier. Conventional nanocarrier can hardly achieve this goal. Herein, doxorubicin and indocyanine green (DOX/ICG) loaded nanocolloidosomes (NCs), with selective drug release, were fabricated as a novel multifunctional theranostic nanoplatform for photothermal/chemo combination therapy. Templating from galactose functionalized hydroxyethyl starch-polycaprolactone (Gal-HES-PCL) nanoparticles stabilized Pickering emulsions, the resultant DOX/ICG@Gal-HES-PCL NCs had a diameter around 140 nm and showed outstanding tumor targeting ability, preferable tumor penetration capability, and promoted photothermal effect...
November 10, 2017: ACS Applied Materials & Interfaces
Yunchong Zhang, Yang Jiang, Lei Han, Bijia Wang, Hong Xu, Yi Zhong, Linping Zhang, Zhiping Mao, Xiaofeng Sui
Reinforcement of biodegradable polymers with nanocellulose is attractive yet the effectiveness is often compromised by uneven dispersion. In this work, a general method of preparing reinforced biodegradable composites using regenerated cellulose (RC) was developed. From an oil-in-water Pickering emulsion of PLA/methylene chloride stabilized with RC, uniformly dispersed RC/PLA composites was obtained. The resulting RC/PLA composites showed enhanced crystallization and tensile strength of up to 34% compared with the native PLA, while the transmittance in the visible range remained above 70%...
January 1, 2018: Carbohydrate Polymers
Junyi Yang, David Roell, Martin Echavarria, Sachin S Velankar
We examine the effect of composition on the morphology of a ternary mixture comprising two molten polymeric liquid phases (polyisobutylene and polyethylene oxide) and micron-scale spherical silica particles. The silica particles were treated with silanes to make them partially wetted by both polymers. Particle loadings up to 30 vol% are examined while varying the fluid phase ratios across a wide range. Numerous effects of particle addition are catalogued, stabilization of Pickering emulsions and of interfacially-jammed co-continuous microstructures, meniscus-bridging of particles, particle-induced coalescence of the dispersed phase, and significant shifts in the phase inversion composition...
November 6, 2017: Soft Matter
Ming Zhang, Rammile Ettelaie, Tao Yan, Suojiang Zhang, Fangqin Cheng, Bernard P Binks, Hengquan Yang
We develop a novel strategy to more effectively and controllably process continuous enzymatic or homogeneous catalysis reactions based on nonaqueous Pickering emulsions. A key element of this strategy is "bottom-up" construction of a macroscale continuous flow reaction system through packing catalyst-containing micron-sized ionic liquid (IL) droplet in oil in a column reactor. Due to the continuous influx of reactants into the droplet microreactors and the continuous release of products from the droplet microreactors, catalysis reactions in such a system can take place without limitations arising from establishment of the reaction equilibrium and catalyst separation, inherent in conventional batch reactions...
November 17, 2017: Journal of the American Chemical Society
Gilad Kaufman, Wei Liu, Danielle M Williams, Youngwoo Choo, Manesh Gopinadhan, Niveditha Samudrala, Raphael Sarfati, Elsa C Y Yan, Lynne Regan, Chinedum O Osuji
Protein adsorption and assembly at interfaces provides a potentially versatile route to create useful constructs for fluid compartmentalization. In this context, we consider the interfacial assembly of a bacterial biofilm protein, BslA, at air-water and oil-water interfaces. Densely packed, high modulus monolayers form at air-water interfaces leading to the formation of flattened sessile water drops. BslA forms elastic sheets at oil-water interfaces leading to the production of stable monodisperse oil-in-water microcapsules...
November 2, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Elshad Allahyarov, Axel Voigt, Hartmut Löwen
The impact of topology on the structure of a smectic monolayer confined to a sphere is explored by particle-resolved computer simulations of hard rods. The orientations of the particles are tangential to the sphere and either free or restricted to a prescribed director field with a latitude or longitude orderings. Depending on the imprinted topology, a wealth of different states are found including equatorial smectic with isotropic poles, equatorial smectic with empty poles, a broken egg-shell like modulated smectic, a capped nematic with equatorial bald patches, equatorial nematic with empty poles, and a situation with 4 or 8 half-strength topological defects...
November 15, 2017: Soft Matter
Marwa Hasanein Asfour, Heba Elmotasem, Dina Mahmoud Mostafa, Abeer A A Salama
The aim of the present study is to formulate the hydrophobic drug rutin in a solubilized form, intended for wound healing, via its loading into a novel Pickering emulsion stabilized by self aggregated chitosan particles (SACP). Rutin-loaded Pickering emulsion formulae were prepared using a high speed homogenizer. They were characterized by drop test, optical microscopy, droplet size and zeta potential determination. The results revealed that SACP have a nano size and a contact angle of 42.47±1.19° that tend to stabilize O/W emulsion...
October 24, 2017: International Journal of Pharmaceutics
Yongmin Zhang, Shuang Guo, Xiaofei Ren, Xuefeng Liu, Yun Fang
Herein, we described for the first time a CO2 and redox dual responsive paraffin oil-in-water Pickering emulsion stabilized by the modified silica nanoparticles with Se-containing tertiary amine, SeTA, in which the tertiary amine serves as a CO2-sensitive group, and the Se atom serves as a redox-sensitive center. The Pickering emulsion can be reversibly switched between stable and unstable states by bubbling CO2 and N2 in the reduced state, or with the addition of H2O2 and Na2SO3 in the absence of CO2, because of the adsorption and desorption of SeTA on the silica surface...
November 3, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Mikhil Ranka, Hari Katepalli, Daniel Blankschtein, T Alan Hatton
Stimuli-responsive pickering emulsions have received considerable attention in recent years, and the utilization of temperature as a stimulus has been of particular interest. Previous efforts have led to responsive systems that enable the formation of stable emulsions at room temperature, which can subsequently be triggered to destabilize with an increase in temperature. The development of a thermoresponsive system that exhibits the opposite response, however, i.e., one that can be triggered to form stable emulsions at elevated temperatures and subsequently be induced to phase separate at lower temperatures, has so far been lacking...
November 8, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Jean Buffiere, Zoltán Balogh-Michels, Marc Borrega, Thomas Geiger, Tanja Zimmermann, Herbert Sixta
This paper takes a comparative approach in characterizing two types of nano-scale cellulosic particles obtained using chemical-free pathways, either by nearcritical water treatment or by high-shear homogenization from the same microcrystalline cellulose (MCC). The nearcritical water treatment efficiently depolymerized cellulose, producing a solid precipitated fraction of low-molecular-weight material containing cellulose II, while homogenization mechanically deconstructed MCC without altering its molecular structure...
December 15, 2017: Carbohydrate Polymers
Jiun-Wen Hu, Mei-Wen Yen, Ae-June Wang, I-Ming Chu
Cyclodextrins (CDs) coupled with oils forms an insoluble inclusion complex that is able to adsorb to the interface between oils and aqueous phases; it thereby stabilizes Pickering emulsions. Three types of oils (triglyceride, linear chain oil, and ring-structured oil) were chosen to work with CDs to prepare bupivacaine (BPC)-encapsulated Pickering emulsions. We also investigated the relationship between oils and CDs; as well as their influences on stability, drug-releasing capability and skin permeability. Particle sizes and microstructures were determined by dynamic light scattering and scanning electron microscopy, respectively...
October 4, 2017: Colloids and Surfaces. B, Biointerfaces
Shun Yang, Yaru Wang, Shiting Lin, Jie Fan, Chang Liu, Xiao Yan
Polymeric absorbents were surface-engineered with photocatalysts for simultaneous adsorption and degradation of organic wastes in water using a facile Pickering emulsion polymerization method. This facile strategy not only overcome the low light energy utilization of traditional photocatalysts-polymer nanocomposites due to the core-shell structure, but also could convenient control the microstructure of the photocatalysts owing to the separated preparation procedure when compared to the direct growth method...
October 4, 2017: Chemosphere
Kate L Thompson, Natacha Cinotti, Elizabeth R Jones, Charlotte J Mable, Patrick W Fowler, Steven P Armes
Sterically stabilized diblock copolymer nanoparticles with an intensity-average diameter of 25 nm are prepared in the form of a concentrated aqueous dispersion using polymerization-induced self-assembly (PISA). The addition of n-dodecane followed by high-shear homogenization produces n-dodecane-in-water Pickering macroemulsions of 22-46 μm diameter. If the nanoparticles are present in sufficient excess, then subsequent processing using a high-pressure microfluidizer leads to the formation of Pickering nanoemulsions with a mean oil droplet diameter below 200 nm...
November 7, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Yiming Li, Haiyue Gong, Hua Cheng, Lisha Wang, Mutai Bao
Effective emulsification plays an important role in the treatment of marine oil spills. The negative effects of chemical surfactants have necessitated a search for alternative dispersant that are sustainable and environmentally-friendly. To identify alternate dispersants, oil-in-seawater emulsions stabilized by hydrocarbon-degrading bacteria were investigated. After individual immobilization and surface-modification, the hydrocarbon-degrading bacteria, Bacillus cereus S-1, was found to produce a stable oil-in-seawater Pickering emulsion, which was similar to particle emulsifiers...
September 29, 2017: Marine Pollution Bulletin
Jinghui Wang, Renliang Huang, Wei Qi, Rongxin Su, Zhimin He
Enzyme-loaded water-in-oil Pickering emulsion is a promising system for biphasic catalytic reactions. In this paper, we report on oriented enzyme immobilization at the oil/water interface in a Pickering emulsion, in which CHO-Janus silica nanoparticles (CHO-JNPs) are utilized as a stabilizer of the emulsion and support for the enzyme to enhance both catalytic activity and recyclability. The catalytic performance of this immobilized enzyme (lipase from Candida sp.) was evaluated by esterification of hexanoic acid and 1-hexanol in a water/heptane biphasic medium...
October 13, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Fanyu Zhang, Lifei Liu, Xiuniang Tan, Xinxin Sang, Jianling Zhang, Chengcheng Liu, Bingxing Zhang, Buxing Han, Guanying Yang
Herein we demonstrate the formation of a novel kind of Pickering emulsion that is stabilized by a Zr-based metal-organic framework (Zr-MOF) and graphene oxide (GO). It was found that the Zr-BDC-NO2 and GO solids assembling at the oil/water interface can effectively stabilize the oil droplets that are dispersed in the water phase. Such a Pickering emulsion offers a facile route for fabricating Zr-MOF/GO composite materials. After removing water and oil by freeze drying from Pickering emulsions, the Zr-MOF/GO composites were obtained and their morphologies, structures and interaction properties were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectrometry, respectively...
October 18, 2017: Soft Matter
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