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Langmuir: the ACS Journal of Surfaces and Colloids

Florence Sarah Blachon, Frederic F Harb, Bogdan Munteanu, Agnès Piednoir, Remy Fulcrand, Thierry Charitat, Giovanna Fragneto, Olivier Pierre-Louis, Bernard Tinland, Jean-Paul Rieu
In vivo lipid membranes interact with rough supramolecular structures such as protein clusters and fibrils. How these features whose size ranges from a few nanometers to a few tens of nanometers impact lipid and protein mobility is still investigated. Here, we study supported phospholipid bilayers, a unique biomimetic model, deposited on etched surfaces bearing nanometric corrugations. Surface roughness and mean curvature are carefully characterized by AFM imaging using ultrasharp tips. Neutron specular reflectivity supplements this surface characterization, and indicates that the bilayers follow the large scale corrugations of the substrate...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Phillip Leon Bartels, Andy Zhou, Anna Ruth Arnold, Nicole N Nunez, Frank Nelson Crespilho, Sheila S David, Jacqueline K Barton
Escherichia coli Endonuclease III (EndoIII) and MutY are DNA glycosylases that contain [4Fe4S] clusters and that serve to maintain the integrity of the genome after oxidative stress. Electrochemical studies on highly-oriented pyrolytic graphite (HOPG) revealed that DNA binding by EndoIII leads to a large negative shift in midpoint potential of the cluster, consistent with stabilization of the oxidized [4Fe4S]3+ form. However, the smooth, hydrophobic HOPG surface is non-ideal for working with proteins in the absence of DNA...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Itai Schlesinger, Uri Sivan
Using an ultra-high resolution AFM operated in frequency modulation mode we extend existing measurements of the force acting between hydrophobic surfaces immersed in water in three essential ways. (1) The measurement range, which was previously limited to distances longer than 2-3 nanometers, is extended to cover all distances, down to contact. The measurements disclose that the long-range attraction observed also by conventional techniques, turns at distances shorter than 1-2 nanometers into pronounced repulsion...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Jocelyn Alice Peach, Adam Czajka, Gavin Hazell, Christopher Hill, Azmi Mohamed, Jonathan C Pegg, Sarah E Rogers, Julian Eastoe
For equivalent micellar volume fraction (Φ) systems containing anisotropic micelles are generally more viscous than those comprising spherical micelles. Many surfactants used in water-in- CO2 (w/c) microemulsions are fluorinated analogues of sodium bis(2-ethylhexyl) sulfosuccinate (AOT): here it is proposed that mixtures of CO2-philic surfactants with hydrotropes and co-surfactants may generate elongated micelles in w/c systems at high-pressures (e.g. 100-400 bar). A range of novel w/c microemulsions, stabilised by new custom-synthesized CO2-phillic, partially fluorinated surfactants, were formulated with hydrotropes and co-surfactant...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Nobuhiro Kawatsuki, Ryosuke Fujii, Yu Fujioka, Satoshi Minami, Mizuho Kondo
The application of a top-coating of 4-methoxy cinnamic acid (MCA) onto a photoinactive liquid crystalline polymeric film containing benzoic acid (BA) side groups (P6BAM) is shown to enable thermally stimulated, photoinduced reorientation of the polymer structure. Annealing the MCA-coated P6BAM films leads to H-bond formation between BA and MCA, which also effectively smooths the film surface. Exposure to linearly polarized (LP) UV light initiates axis-selective photoreaction of the MCA groups; subsequent thermal treatment in the LC temperature range of P6BAM amplifies molecular reorientation of the BA side groups, while simultaneously eliminating the MCA molecules...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Matthew Mullen, William B Euler
The spectral response of ultrathin films of rhodamine 6G (Rh6G) cast onto polyvinylidenefluoride (PVDF) coated glass slides is studied to investigate a perceived fluorescence emission enhancement. Varying the thickness of the Rh6G layer (submonolayer to multiple layers) on the PVDF layer revealed the existence of multiple Rh6G species on the surface, similar to previous reports on glass. Excitation spectra show that J-type excitons are not responsible for an emission enhancement. Trends in the fluorescence emission intensity show that the surface roughness of the PVDF layer prevents the Rh6G molecules from organizing the way they would on a smooth glass surface...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Victor A Ermakov, Ernesto Jimenez-Villar, José Maria Clemente da Silva Filho, Emre Yassitepe, Naga Vishnu Vardhan Mogili, Fernando Iikawa, Gilberto Fernandes de Sá, Carlos Lenz Cesar, Francisco Chagas Marques
Aqueous colloidal silver nanoparticles have substantial potential in biological application as markers and antibacterial agents and in surface-enhanced Raman spectroscopy applications. A simple method of fabrication and encapsulation into an inert shell is of great importance today to make their use ubiquitous. Here we show that colloids of silver-core/silica-shell nanoparticles can be easily fabricated by a laser-ablation-assisted chemical reduction method and their sizes can be tuned in the range of 2.5 to 6...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Tibor Müllner, Armin Zankel, Alexandra Höltzel, Frantisek Svec, Ulrich Tallarek
Shaping chemical interfaces of hard and soft matter materials into physical morphologies that guarantee excellent transport properties is of central importance for technologies relying on adsorption, separation, and reaction at the interface. Polymer monoliths with a hierarchically structured pore space, for example, are widely used in flow-driven processes, whose efficiency depends on the morphology of the support material over several length scales. Compared with alternative support structures, particularly silica monoliths, polymer monoliths yield lower efficiency, which suggests a suboptimal morphology...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Maho Kobayashi, Kyoka Susuki, Haruo Otsuji, Yusuke Sakuda, Shunsuke Asahina, Naoki Kikuchi, Toshiyuki Kanazawa, Yoshiyuki Kuroda, Hiroaki Wada, Atsushi Shimojima, Kazuyuki Kuroda
The properties of the outermost surfaces of mesoporous silica thin films are critical in determining their functions. Obtaining information on the presence or absence of silica layers on the film surfaces and on the degree of mesopore opening is essential for applications of surface mesopores. In this study, the outermost surfaces of mesoporous silica thin films with 3-dimensional orthorhombic and 2-dimensional hexagonal structures were observed using ultralow voltage high resolution scanning electron microscopy (HR-SEM) with decelerating optics...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Arghya Chakravorty, Zhe Jia, Lin Li, Emil Alexov
A new feature of the popular software DelPhi is developed and reported, allowing for computing the surface averaged electrostatic potential (SAEP) of macromolecules. The user is given the option to specify the distance from the van der Waals surface where the electrostatic potential will be outputted. In conjunction with DelPhiPKa and the BION server, the user can adjust the charges of titratable groups according to specific pH values, and add explicit ions bound to the macromolecular surface. This approach is applied to a set of four proteins with "experimentally" delivered zeta (ζ)-potentials at different pH values and salt concentrations...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Lu Lai, Sheng-Jin Li, Jing Feng, Ping Mei, Zhao-Hua Ren, Yan-Ling Chang, Yi Liu
The inhibitory effects of CdTe/ZnS quantum dots (QDs) modified with 3-mercaptopropionic acid (negatively charged) or cysteamine (positively charged) on the metabolic activity of Escherichia coli were investigated using biological microcalorimetry. Results show that the inhibitory ratio of positive QDs is higher than that of negative QDs. Transmission electron microscopy images indicate that QDs are prone to be adsorbed on the surface of E. coli. This condition disturbs the membrane structure and function of E...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Kyle M McElhinny, Peishen Huang, Yongho Joo, Catherine Kanimozhi, Arunee Lakkham, Kenji Sakurai, Paul G Evans, Padma Gopalan
The structural configuration of molecules assembled at organic-inorganic interfaces within electronic materials strongly influences the functional electronic and vibrational properties relevant to applications ranging from energy storage to photovoltaics. Controlling and characterizing the structural state of an interface and its evolution under external stimuli is crucial both for the fundamental understanding of the factors influenced by molecular structure and for the development of methods for material synthesis...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Francesco Spinozzi, Giacomo Ceccone, Paolo Moretti, Gabriele Campanella, Claudio Ferrero, Sophie Combet, Isaac Ojea-Jimenez, Paolo Ghigna
We propose a novel method for determining the structural and thermodynamic properties of nanoparticle-protein complexes under physiological conditions. The method consists of collecting a full set of small-angle X-ray and neutron-scattering measurements in solutions with different concentrations of nanoparticles and protein. The nanoparticle-protein dissociation process is described in the framework of the Hill cooperative model, based on which the whole set of X-ray and neutron-scattering data is fitted simultaneously...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Benjamin L Micklavzina, Shengwei Zhang, Hao He, Marjorie L Longo
In this work, we study the mechanical properties of sodium dodecyl sulfate (SDS) and dodecylamine hydrochloride (DAH) micellar films at a graphite surface via atomic force microscopy (AFM). Breakthrough forces for these films were measured using silicon nitride cantilevers and were found to be 1.1 ± 0.1 nN for a 10 mM DAH film and 3.0 ± 0.3 nN for a 10 mM SDS film. For 10 mM SDS films, it was found that the addition of 1.5 mM of NaCl, Na2SO4, or MgCl2 produced a 50-70% increase in the measured breakthrough force...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Surendra Kumar Jain, Roland J-M Pellenq, Keith E Gubbins, Xuan Peng
Realistic molecular models of silica-templated CMK-1, CMK-3, and CMK-5 carbon materials have been developed by using carbon rods and carbon pipes that were obtained by adsorbing carbon in a model MCM-41 pore. The interactions between the carbon atoms with the silica matrix were described using the PN-Traz potential, and the interaction between the carbon atoms was calculated by the reactive empirical bond order (REBO) potential. Carbon rods and pipes with different thicknesses were obtained by changing the silica-carbon interaction strength, the temperature, and the chemical potential of carbon vapor adsorption...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Sergej Püschel-Schlotthauer, Victor Meiwes Turrión, Carol K Hall, Marco G Mazza, Martin Schoen
Liquid-crystalline phases are known for their unique properties, i.e., the combination of fluidity and long-range orientational and/or positional order. The presence of a colloidal particle gives rise to perturbations of this order locally. These perturbations are the origin of intercolloidal forces driving the colloidal self-assembly in a directed manner. Hence, the understanding of these perturbations is the first step in understanding and controlling the self-assembly process. Here, we perform Monte Carlo simulations to investigate the perturbations of orientational and positional order in a smectic A phase caused by a spherical colloid...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Qiaoshan Chen, Caiyun Jia, Yu Li, Jie Xu, Baohong Guan, Matthew Z Yates
The past decades have witnessed great advances in nanotechnology since tremendous efforts have been devoted for the design, synthesis, and application of nanoparticles. However, for most mineral materials such as calcium sulfate, it is still a challenge to prepare their nanoparticles, especially with uniform size and high monodispersity. In this work, we report a route to regulate the morphology and structure of α-calcium sulfate hemihydrate (α-HH) and successfully synthesize and stabilize its mesocrystals for the first time...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Shiyang Jia, Joanne D Du, Adrian Hawley, Wye-Khay Fong, Bim Graham, Ben J Boyd
The ability of donor-acceptor Stenhouse adducts (DASAs) to function as a green light responsive switch for lipid-based liquid crystalline drug delivery systems was investigated. The host matrix comprising phytantriol cubic phase was selected due to its high sensitivity toward changes in lipid packing. Small-angle X-ray scattering demonstrated that the matrix undergoes rapid and fully reversible order-order phase transitions upon irradiation with 532 nm light, converting between the bicontinuous cubic phase and reversed hexagonal phases...
February 20, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Guannan Ju, Jing Liu, Donglin Li, Mengjiao Cheng, Feng Shi
Oil spill accidents normally have two important features when considering practical clean-up strategies: (1) unexpected occurrence in any situations possibly without specific equipment and chemicals; (2) emergency to be cleaned to minimize the influences on ecosystems. To address these two practical problems regarding removal of spilt oil, we have proposed an in situ, rapid and facile candle-soot strategy to fabricate water/oil separating materials based on superhydrophobicity/superoleophilicity. The one-step fabrication method is independent on any chemicals or equipment and can be ready for use through short smoking processes within 5 min by using raw materials available in daily life such as textiles...
February 19, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
George W Greene, Rajiv Thapa, Stephen Andrew Holt, Xiaoen Wang, Christopher J Garvey, Rico F Tabor
Lubricin is a "mucin-like" glycoprotein found in synovial fluids and coating the cartilage surfaces of articular joints which is now generally accepted as one of the body's primary boundary lubricants and anti-adhesive agents. Lubricin's superior lubrication and anti-adhesion are believed to derive from its unique interfacial properties by which lubricin molecules adhere to surfaces (and biomolecules, including hyaluronic acid and collagen) through discrete interactions localized to its two terminal end-domains...
February 18, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
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