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Myong In Oh, Styliani Consta
Electrospray ionization mass spectrometry (ESI-MS) has the potential to become a high-throughput robust experimental method for the detection of protein-protein equilibrium constants. Poorly understood processes that affect the stability of weak non-covalent protein complexes in the intervening droplet environment is a significant factor that precludes the advancement of the method. We use molecular dynamics to study the stability of a ubiquitin and ubiquitin-associated domain complex (RCSB PDB code 2MRO) in an aqueous droplet with changing size and charge concentration...
December 9, 2016: Journal of Physical Chemistry Letters
Mahesh Kharat, Zheyuan Du, Guodong Zhang, David Julian McClements
The utilization of curcumin as a nutraceutical in food and supplement products is often limited because of its low-water solubility, poor chemical stability, and low oral bioavailability. This study examined the impact of pH, storage temperature, and molecular environment on the physical and chemical stability of pure curcumin in aqueous solutions and in oil-in-water emulsions. Unlike naturally occurring curcuminoid mixtures (that contain curcumin, demethoxy-curcumin and bisdemethoxy-curcumin), pure curcumin was highly unstable to chemical degradation in alkaline aqueous solutions (pH ≥ 7...
December 9, 2016: Journal of Agricultural and Food Chemistry
Taro Omura, Kaori Imagawa, Kyosuke Kono, Toyoko Suzuki, Hideto Minami
We have reported the cellulose particles with a spongy structure, which we prepared by the solvent releasing method (SRM) from cellulose droplets comprising cellulose, 1-butyl-3-methylimidazoliumchrolide ([Bmim]Cl), and N,N-dimethylformamide (DMF). The spongy structure collapsed as the medium evaporated, resulting in dense cellulose particles. In this study, we encapsulated the hydrophilic and hydrophobic fluorescent substances in these particles to investigate the use of such particles in potential applications that require encapsulating of substances (e...
December 9, 2016: ACS Applied Materials & Interfaces
Lauriane Alison, Patrick A Rühs, Elena Tervoort, Alexandra Teleki, Michele Zanini, Lucio Isa, André R Studart
Edible solid particles constitute an attractive alternative to surfactants as stabilizers of food-grade emulsions for products requiring a long-term shelf life. Here, we report on a new approach to stabilize edible emulsions using silica nanoparticles modified by noncovalently bound chitosan oligomers. Electrostatic modification with chitosan increases the hydrophobicity of the silica nanoparticles and favors their adsorption at the oil-water interface. The interfacial adsorption of the chitosan-modified silica particles enables the preparation of oil-in-water emulsions with small droplet sizes of a few micrometers through high-pressure homogenization...
December 9, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Dhiman Das, Dinh Tuan Phan, Zhao Yugang, Kang Yuejun, Vincent Chan, Chun Yang
A novel continuous flow microfluidic platform specifically designed for environmental monitoring of O/W emulsions during an aftermath of oil spills is reported herein. Ionized polycyclic aromatic hydrocarbons which are toxic are readily released from crude oil to the surrounding water phase through the smaller oil droplets with enhanced surface area. Hence, a multi-module microfluidic device is fabricated to (1) form ion enrichment zones in the water phase of O/W emulsions for the ease of detection and (2) to separate micron-sized oil droplets from the O/W emulsions...
December 9, 2016: Electrophoresis
Naomi C Delic, J Guy Lyons, Nick Di Girolamo, Gary M Halliday
The cornea sits at the anterior aspect of the eye and additionally to the skin, is highly exposed to ultraviolet radiation (UVR). The cornea blocks a significant proportion of UVB from reaching the posterior structures of the eye. However, UVA can penetrate the full thickness of the cornea, even reaching the anterior portion of the lens. Epidemiological data indicate that UVR is a contributing factor for a multitude of corneal diseases of the cornea including pterygium, photokeratitis, climatic droplet keratopathy, (CDK) and ocular surface squamous neoplasia (OSSN), although the pathogenic mechanisms of each require further elucidation...
December 9, 2016: Photochemistry and Photobiology
Rafael D Schulman, Amir Porat, Kathleen Charlesworth, Adam Fortais, Thomas Salez, Elie Raphaël, Kari Dalnoki-Veress
We report on the elastocapillary deformation of flexible microfibers in contact with liquid droplets. A fiber is observed to bend more as the size of the contacting droplet is increased. At a critical droplet size, proportional to the bending elastocapillary length, the fiber is seen to spontaneously wind around the droplet. To rationalize these observations, we invoke a minimal model based on elastic beam theory, and find agreement with experimental data. Further energetic considerations provide a consistent prediction for the winding criterion...
December 9, 2016: Soft Matter
A K L Oppermann, L C Verkaaik, M Stieger, E Scholten
Double (w1/o/w2) emulsions are potential fat replacers in foods. Fats are known for their lubricating properties, which contribute to texture perception. It is therefore of interest to understand how the composition of double emulsions influences lubrication properties. This study focuses on the understanding of the influence of the fraction of inner dispersed aqueous phase w1 and the gelation of the w1 droplets on the lubrication properties of double emulsions. The addition of an inner water phase w1 to the oil droplets decreased friction at low entrainment speeds due to adsorption of the lipophilic emulsifier polyglycerol polyricinoleate (PGPR) at the hydrophobic tribo-surface...
December 9, 2016: Food & Function
Bekir Sami Yilbas, Billel Salhi, Muhammad Rizwan Yousaf, Fahad Al-Sulaiman, Haider Ali, Nasser Al-Aqeeli
In this study, nanowires/nanowalls were generated on a silicon wafer through a chemical etching method. Octadecyltrichlorosilane (OTS) was deposited onto the nanowire/nanowall surfaces to alter their hydrophobicity. The hydrophobic characteristics of the surfaces were further modified via a 1.5-μm-thick layer of n-octadecane coating on the OTS-deposited surface. The hydrophobic characteristics of the resulting surfaces were assessed using the sessile water droplet method. Scratch and ultraviolet (UV)-visible reflectivity tests were conducted to measure the friction coefficient and reflectivity of the surfaces...
December 9, 2016: Scientific Reports
Rong Zhu, Xinyu Wang, Jing Yang, Yiyu Wang, Zongrui Zhang, Yuanjing Hou, Fei Lin
The present study describes a series of novel polycarbonate urethane films that were fabricated via the solution-casting method from 4,4'-methylenebis(cyclohexyl isocyanate) (H12MDI) and 1,4-butanediol (BDO) chain extender as hard segments, poly(1,6-hexanediol)carbonate diols (PCDL) and hydroxyl-terminated polydimethylsiloxane (PDMS) as soft segments, with dibutyltin dilaurate as the catalyst. Varied molar ratios of PDMS (less than 30%) were utilized to enhance the mechanical properties and biocompatibilities...
December 9, 2016: Biomedical Materials
Steve Arscott
A chemically driven dewetting effect is demonstrated using sessile droplets of dilute hydrofluoric acid on chemically oxidized silicon wafers. The dewetting occurs as the thin oxide is slowly etched by the droplet and replaced by a hydrogen-terminated surface; the result of this is a gradual increase in the contact angle of the droplet with time. The time-varying work of adhesion is calculated from the time-varying contact angle; this corresponds to the changing chemical nature of the surface during dewetting and can be modeled by the well-known logistic (sigmoid) function often used for the modeling of restricted growth, in this case, the transition from an oxidized surface to a hydrogen-terminated silicon surface...
December 6, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Tae-Ho Kim, Hyeri Kim, Ki-In Choi, Jeseung Yoo, Young-Soo Seo, Jeong-Soo Lee, Jaseung Koo
We investigate the effect of adding graphene oxide (GO) sheets at the polymer-polymer interface on the dewetting dynamics and compatibility of immiscible polymer bilayer films. GO monolayers are deposited at the poly(methyl methacrylate) (PMMA)-polystyrene (PS) interface by the Langmuir-Schaefer technique. GO monolayers are found to significantly inhibit the dewetting behavior of both PMMA films (on PS substrates) and PS films (on PMMA substrates). This can be interpreted in terms of an interfacial interaction between the GO sheets and these polymers, which is evidenced by the reduced contact angle of the dewet droplets...
December 6, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Greyson W Waldhart, Neal P Mankad, Bernard D Santarsiero
A microwell droplet approach provided high-quality samples in ≥90% yield of the "crystalline sponge", which was exhibited previously as a revolutionary organic structure determination method. The new protocol, from crystal growth to guest soaking, was conducted in 1-7 days (depending on the guest) and was robust toward user errors, marking improvements over existing protocols. Unit cell determination was used as a practical crystal screening metric. These advances improve the practicality of the crystalline sponge technique for characterizing unknown organic molecules...
December 2, 2016: Organic Letters
Tahnee J Dening, Paul Joyce, Shasha Rao, Nicky Thomas, Clive A Prestidge
Biocompatible lipid hybrid particles composed of montmorillonite and medium chain triglycerides were engineered for the first time by spray drying oil-in-water emulsions stabilized by montmorillonite platelets to form montmorillonite-lipid hybrid (MLH) microparticles containing up to 75% w/w lipid. In vitro lipolysis studies under simulated intestinal conditions indicated that the specific porous nanoarchitecture and surface chemistry of MLH particles significantly increased the rate (>10-fold) and extent of lipase-mediated digestion compared to that of coarse and homogenized submicrometer triglyceride emulsions...
December 7, 2016: ACS Applied Materials & Interfaces
Shengnan Wang, Min Chen, Limin Wu
A facile, one-step method to prepare cagelike hollow silica nanospheres with large through-holes (HSNLs) using a lysozyme-assisted O/W miniemulsion technique is presented. The tetraethoxysilane (TEOS)-xylene mixture forms oil droplets which are stabilized by the cationic surfactant cetyltrimethylammonium bromide (CTAB), cosurfactant hexadecane (HD), and protein lysozyme. HSNLs (with diameter of 300-460 nm) with large through-holes (10-30 nm) were obtained directly after ultrasonic treatment and aging. Lysozyme can not only stabilize the oil/water interface, assist the hydrolysis of TEOS, and interact with silica particles to assemble into silica-lysozyme clusters but also contribute to the formation of through-holes due to its hydrophilicity variation at different pH conditions...
December 7, 2016: ACS Applied Materials & Interfaces
Heidi Toft Hansen, Christian Janfelt
Internal standards have been introduced in quantitative mass spectrometry imaging in order to compensate for differences in intensities throughout an image caused by, for example, difference in ion suppression or analyte extraction efficiency. To test how well the internal standards compensate for differences in tissue types in, for example, whole-body imaging, a set of tissue homogenates of different tissue types (lung, liver, kidney, heart, and brain) from rabbit was spiked to the same concentration with the drug amitriptyline and imaged in the same experiment using isotope labeled amitriptyline as internal standard...
December 6, 2016: Analytical Chemistry
Lylian Challier, Rebeca Miranda-Castro, Bertrand Barbe, Claire Fave, Benoît Limoges, Eric Peyrin, Corinne Ravelet, Emmanuelle Fiore, Pierre Labbé, Liliane Coche-Guérente, Eric Ennifar, Guillaume Bec, Philippe Dumas, François Mavré, Vincent Noël
Nucleic acid aptamers are involved in a broad field of applications ranging from therapeutics to analytics. Deciphering the binding mechanisms between aptamers and small ligands is therefore crucial to improve and optimize existing applications and to develop new ones. Particularly interesting is the enantiospecific binding mechanism involving small molecules with nonprestructured aptamers. One archetypal example is the chiral binding between l-tyrosinamide and its 49-mer aptamer for which neither structural nor mechanistic information is available...
December 6, 2016: Analytical Chemistry
Daniel J Merthe, Vitaly V Kresin
Electric deflection measurements on liquid helium nanodroplets doped with individual polar molecules demonstrate that the cold superfluid matrix enables full orientation of the molecular dipole along the external field. This translates into a deflection force that is increased enormously by comparison with typical deflection experiments, and it becomes possible to measurably deflect neutral doped droplets with masses of tens to hundreds of thousands of Daltons. By using continuous fluxes of fully oriented polar molecules and measuring the deflection of the doped nanodroplet beam, this approach makes it possible to directly determine the dipole moments of internally cryogenically cold molecules...
December 1, 2016: Journal of Physical Chemistry Letters
Hallie C Boyer, Bryan Richard Bzdek, Jonathan Philip Reid, Cari S Dutcher
The surface composition and tensions of aqueous aerosols govern a set of processes that largely determine the fate of particles in the atmosphere. Predictive modeling of surface tension can provide significant contributions to studies of atmospheric aerosol effects on climate and human health. A previously derived surface tension model for single solute aqueous solutions used adsorption isotherms and statistical mechanics to enable surface tension predictions across the entire concentration range as a function of solute activity...
December 9, 2016: Journal of Physical Chemistry. A
Robert J Buszek, Claron J Ridge, Samuel B Emery, C Michael Lindsay, Jerry A Boatz
In a recently reported helium droplet-mediated deposition experiment to produce copper-coated magnesium core-shell nanoclusters, structural inversion was observed, which resulted in copper in the nanocluster interior, surrounded by oxidized magnesium on the copper surface. This study utilizes density functional theory methods to model the migration of copper atoms into the interior of a magnesium nanocluster to probe the energetics of this process and to compare it to the complementary process of magnesium atom migration into the interior of a copper nanocluster...
December 8, 2016: Journal of Physical Chemistry. A
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