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Janus particles

M Kasko, V Kasko, S Oravec
Low-density lipoprotein cholesterol (LDL-C) is generally considered to be pro-atherogenic and high-density lipoprotein cholesterol (HDL-C) to be anti-atherogenic. The clinical approach to the diagnostics and treatment of clinical manifestations of atherosclerosis is the examination of the lipid spectrum. In routine clinical practice, the effects of the HDL class are measured only by determining the concentration of HDL cholesterol. It is questionable whether this clinical approach provides sufficient information to evaluate both the overall cardiovascular risk and the effect of hypolipidemic therapy...
2018: Bratislavské Lekárske Listy
Edyta Swider, Olga Koshkina, Jurjen Tel, Luis J Cruz, I Jolanda M de Vries, Mangala Srinivas
Nano- and microparticles have increasingly widespread applications in nanomedicine, ranging from drug delivery to imaging. Poly(lactic-co-glycolic acid) (PLGA) particles are the most widely-applied type of particles due to their biocompatibility and biodegradability. Here, we discuss the preparation of PLGA particles, and various modifications to tailor particles for applications in biological systems. We highlight new preparation approaches, including microfluidics and PRINT method, and modifications of PLGA particles resulting in novel or responsive properties, such as Janus or upconversion particles...
April 10, 2018: Acta Biomaterialia
Maciej Lisicki, Shang Yik Reigh, Eric Lauga
Janus particles with the ability to move phoretically in self-generated chemical concentration gradients are model systems for active matter. Their motion typically consists of straight paths with rotational diffusion being the dominant reorientation mechanism. In this paper, we show theoretically that by a suitable surface coverage of both activity and mobility, translational and rotational motion can be induced arbitrarily in three dimensions. The resulting trajectories are in general helical, and their pitch and radius can be controlled by adjusting the angle between the translational and angular velocity...
April 12, 2018: Soft Matter
Saki Yoshida, Shu Kikuchi, Shinji Kanehashi, Kazuo Okamoto, Kenji Ogino
Multicomponent polymer particles with specific morphology are promising materials exhibiting novel functionality which cannot be obtained with single-component polymer particles. Particularly, the preparation of such kinds of polymer particles involving electrically or optically active conjugated polymers with uniform size is a challenging subject due to their intense demands. Here, microspheres of binary polymer blend consisting of poly(4-butyltriphenylamine) (PBTPA)/poly(methyl methacrylate) (PMMA) (1:1 in weight) were produced via a microfluidic emulsification with a Y-shaped microreactor, and a subsequent solvent evaporation method...
April 10, 2018: Materials
Richard J Archer, Andrew J Parnell, Andrew I Campbell, Jonathan R Howse, Stephen J Ebbens
The field of active colloids is attracting significant interest to both enable applications and allow investigations of new collective colloidal phenomena. One convenient active colloidal system that has been much studied is spherical Janus particles, where a hemispherical coating of platinum decomposes hydrogen peroxide to produce rapid motion. However, at present producing these active colloids relies on a physical vapor deposition (PVD) process, which is difficult to scale and requires access to expensive equipment...
February 2018: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Jian Liu, Tingting Liu, Jian Pan, Shaomin Liu, G Q Max Lu
Mesoporous silica nanoparticles (MSNs) are promising functional nanomaterials for a variety of biomedical applications, such as bioimaging, drug/gene delivery, and cancer therapy. This is due to their low density, low toxicity, high biocompatibility, large specific surface areas, and excellent thermal and mechanical stability. The past decade has seen rapid advances in the development of MSNs with multiple compartments. These include hierarchical porous structures and core-shell, yolk-shell, and Janus structured particles for efficient diagnosis and therapeutic applications...
April 4, 2018: Annual Review of Chemical and Biomolecular Engineering
Kwahun Lee, Liuyang Zhang, Yi Yi, Xianqiao Wang, Yan Yu
The surface coatings of nanoparticles determine their interaction with biomembranes, but studies have been limited almost exclusively to nanoparticles with a uniform surface chemistry. Although nanoparticles are increasingly made with complex surface chemistries to achieve multi-functionalities, our understanding of how a heterogeneous surface coating affects particle-biomembrane interaction has been lagging far behind. Here we report an investigation of this question in an experimental system consisting of amphiphilic "two-faced" Janus nanoparticles and supported lipid membranes...
April 4, 2018: ACS Nano
Wesley F Reinhart, Athanassios Z Panagiotopoulos
We measure the kinetics of crystal growth from a melt of triblock Janus colloids using non-equilibrium molecular dynamics simulations. We assess the impact of interaction anisotropy by systematically varying the size of the attractive patches from 40% to 100% coverage, finding substantially different growth behaviors in the two limits. With isotropic particles, the interface velocity is directly proportional to the subcooling, in agreement with previous studies. With highly anisotropic particles, the growth curves are well approximated by using a power law with exponent and prefactor that depend strongly on the particular surface geometry and patch fraction...
March 28, 2018: Journal of Chemical Physics
Qiaohong Peng, Hailin Cong, Bing Yu, Li Wei, Khalid Mahmood, Hua Yuan, Ruixia Yang, Xiaoyan Zhang, Yue Wu
Anisotropic Janus particles are of great interest for many applications. It is well known that behavior and utility of Janus particles are highly dependent on their chemistry and geometry. Herein, we report the synthesis of monodisperse polymeric Janus microparticles that were anisotropic not only in chemistry and shape but also in surface morphology and porosity, via a modified seeded polymerization technique. Chemical composition, shape, morphology and porosity of the polymeric Janus microparticles were flexibly controlled by utilizing different quantities and species of monomer and porogen...
March 21, 2018: Journal of Colloid and Interface Science
Zaiyi Shen, Alois Würger, Juho S Lintuvuori
Using lattice Boltzmann simulations we study the hydrodynamics of an active spherical particle near a no-slip wall. We develop a computational model for an active Janus particle, by considering different and independent mobilities on the two hemispheres and compare the behaviour to a standard squirmer model. We show that the topology of the far-field hydrodynamic nature of the active Janus particle is similar to the standard squirmer model, but in the near-field the hydrodynamics differ. In order to study how the near-field effects affect the interaction between the particle and a flat wall, we compare the behaviour of a Janus swimmer and a squirmer near a no-slip surface via extensive numerical simulations...
March 27, 2018: European Physical Journal. E, Soft Matter
Guolong Zhu, Zihan Huang, Ziyang Xu, Li-Tang Yan
The ability to tailor the interfacial behaviors of nanoparticles (NPs) is crucial not only for the design of novel nanostructured materials with superior properties and of interest for many promising applications such as water purification, enhanced oil recovery, and innovative energy transduction, but also for a better insight into many biological systems where nanoscale particles such as proteins or viruses can interact and organize at certain interfaces. As a class of emerging building blocks, Janus NPs consisting of two compartments of different chemistry or polarity are ideal candidates to generate tunable and stable interfacial nanostructures because of the asymmetric nature...
March 28, 2018: Accounts of Chemical Research
Anna Kozina, Salvador Ramos, Pedro Díaz-Leyva, Rolando Castillo
We study mixtures of amphiphilic Janus and homogeneous hydrophobic particles trapped at an air/water interface. In contrast to an expected monolayer formation, bilayers of colloidal particles are produced. Despite their strong interfacial adsorption, Janus particles form the upper layer. They are not placed on top of the other particles but rather shifted about one-third of the particle diameter. To understand the mechanism of bilayer formation, particle behaviour at the surface and in the bulk of the spreading solvent is considered...
March 26, 2018: Soft Matter
David Alexander Gregory, Stephen J Ebbens
While much attention has focused on self-motile asymmetrical catalytically active "Janus" colloids as a route to enable new fluidic transport applications, the motion of symmetrical catalytically active colloids is less well investigated. This is despite isotopically active colloids being more accessible, and commonly used as supports for heterogeneous catalysis. Here, we addressed this by systematically investigating the motion of platinum- coated colloids capable of isotropically decomposing hydrogen peroxide...
March 21, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
J Harder, A Cacciuto
We use computer simulations to study the behavior of a mixture of large passive charged colloids in a suspension of smaller active dipolar Janus particles. We find that when a single charged colloid is present in solution, it acquires a rotational or translational motion depending on how the active dipoles self-assemble on its surface to form active complexes. The collective behavior of these complexes is quite remarkable, and includes swarming behavior and coherent macroscopic motion. We detail how the variety of different phenomenologies emerging in this system can ultimately be controlled by the strength of the active forces and the relative concentration of the two species...
February 2018: Physical Review. E
Brooke W Longbottom, Stefan A F Bon
Microspheres with catalytic caps have become a popular model system for studying self-propelled colloids. Existing experimental studies involve predominantly "smooth" particle surfaces. In this study we determine the effect of irregular surface deformations on the propulsive mechanism with a particular focus on speed. The particle surfaces of polymer microspheres were deformed prior to depositing a layer of platinum which resulted in the formation of nanoscopic pillars of catalyst. Self-propulsion was induced upon exposure of the micromotors to hydrogen peroxide, whilst they were dispersed in water...
March 15, 2018: Scientific Reports
Khaoula Lebdioua, Anne Aimable, Manuella Cerbelaud, Arnaud Videcoq, Claire Peyratout
HYPOTHESIS: Pickering emulsions were prepared using wax and silica submicronic particles (650 nm), as a first step towards the synthesis of Janus particles. Surfactants added to silica particles control the emulsion stability and particles arrangement, i.e. their penetration depth into the wax and their ability to form a monolayer. Thus, a systematic study of surfactants is proposed. EXPERIMENTS: Zeta potential measurements and sedimentation tests are conducted to evaluate interactions of two cationic (CTAB: hexadecyltrimethylammonium bromide and DDAB: didodecyldimethylammonium bromide) and two polymeric surfactants with silica surface...
March 7, 2018: Journal of Colloid and Interface Science
Chengjun Kang, Andrei Honciuc
The self-assembly of micro/nanoparticles into suprastructures is a promising way to develop reconfigurable materials and to gain insights into the fundamental question of how matter organizes itself. The geometry of particles, especially those deviating from perfectly spherical shapes, is of significant importance in colloidal assembly because it influences the particle "recognition", determines the particle packing, and ultimately dictates the formation of assembled suprastructures. In order to organize particles into desired structures, it is of vital importance to understand the relationship between the shape of the colloidal building blocks and the assembled suprastructures...
March 7, 2018: ACS Nano
Chengjun Kang, Andrei Honciuc
One of the greatest challenges in colloidal self-assembly is to obtain multiple distinct but transformable suprastructures from the same particles in monophasic solvent. Here, we combined deformable and rigid lobes in snowman-shaped amphiphilic Janus nanoparticles (JNPs). These JNPs exhibited excellent ability to self-assemble into micelles, worms, mini-capsules, giant- and elongated-vesicles. This rich suprastructural diversity was obtained by kinetic manipulation of the self-assembly conditions. The suprastructures consist of four to thousands of highly oriented JNPs with dimensions ranging from 500-nanometer to 30-μm...
March 7, 2018: Journal of Physical Chemistry Letters
Kamlesh Panwar, Manjeet Jassal, Ashwini K Agrawal
Silver-silica (Ag-SiO2 ) Janus particles with varying functionalities i.e. amine, thiol and epoxy on the exposed surface of SiO2 particles were synthesized and explored for their antimicrobial activity. Due to their easy dispersibility, Janus particles with silver nanoparticles (AgNPs) of diameter ∼3 nm showed much lower minimum bactericidal concentration (MBC) as compared to conventional isotropic AgNPs powder having AgNPs of almost similar diameter. The isotropic AgNPs and functionalized Ag-SiO2 Janus particles were attached on cotton fabric using exhaustion method followed by curing...
May 1, 2018: Carbohydrate Polymers
Bing Han, Wendi Xia, Kaining Liu, Fucong Tian, Ying Chen, Xiaoyan Wang, Fuxin Liang, Zhenzhong Yang
The amphiphilic monomer 2-hydroxyethyl methacrylate (HEMA) is widely used in dental adhesives as a priming component, especially for dentin bonding. It behaves as a compatibilizer between hydrophilic and hydrophobic components, and stabilizes the multi-component adhesive system. However, there are several drawbacks associated with using HEMA, such as water retention within the adhesive layer, hydrolysis in oral environments, and cytotoxicity. These drawbacks lead to the failure of tooth restoration and represent a heavy medical burden...
February 22, 2018: ACS Applied Materials & Interfaces
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