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Langmuir: the ACS Journal of Surfaces and Colloids

Ye Yang, Pengyu Chen, Yufei Cao, Zihan Huang, Guo-Long Zhu, Ziyang Xu, Xiaobin Dai, Shi Chen, Bing Miao, Li-Tang Yan
The ability to understand and exploit entropic contributions to ordering transition is of essential importance in the design of self-assembling systems with well-controlled structures. However, much less is known about the role of assembly kinetics in entropy-driven phase behaviors. Here, by combining computer simulations and theoretical analysis we report that the implementation of entropy in driving phase transition significantly depends on the kinetic process in the reaction-induced self-assembly of newly designed nanoparticle systems...
July 17, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Diego Pradilla, Ana Barrera, May Grete Sætran, Geir Sørland, Oscar Alvarez
The long-term physical stability of surfactant-stabilized (Span80® and Tween20®) concentrated water-in-mineral oil (W/O) emulsions in the presence of an electrolyte (NaCl) was studied. Pulse field gradient NMR and rheology (bulk and interfacial) were used to probe the response at the macroscopic, microscopic and molecular levels rendering a multi-scale approach. Results show that: i) emulsions prepared with NaCl exhibit higher values of the elastic shear modulus (G_(with NaCl)^'>G_(without NaCl)^') even after ~20 days, ii) the stabilization effect of salt against coarsening of droplets is not due to differences in droplet size (and thus G') or the energy incorporated through emulsification and iii) NaCl relaxes the liquid-liquid interface via a salting-in effect which results in a lower interfacial shear elasticity (G_(with NaCl)^s'<G_(without NaCl)^s') but a higher resistance to coarsening events due to changes in the adsorption density of the layer...
July 17, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Massimo Tawfilas, Michele Mauri, Luca De Trizio, Roberto Lorenzi, Roberto Simonutti
Nanocrystals (NCs) surface characterization is a fundamental step for understanding the physical and chemical phenomena involved at the nanoscale. Surface energy and chemistry depend on particle size and composition, and in turn determine the interaction of NCs with the surrounding environment, their properties and stability, and the feasibility of nanocomposites. This work aims at extracting more information on the surface of different titanium dioxide polymorphs using 1H-TD-NMR of water. Taking advantage of the interaction between water molecules and titanium dioxide NCs it is possible to correlate the proton transverse relaxation times (T2) as function of the concentration and the specific surface area (δ_p∙C_m) and use it as an indicator of the crystal phase...
July 17, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Taisiia Berestok, Pablo Guardia, Maria Ibáñez, Michaela Meyns, Massimo Colombo, Maksym V Kovalenko, Francesca Peiró, Andreu Cabot
The assembly of colloidal nanocrystals (NCs) is a unique strategy to produce porous materials with high crystallinity and unmatched control over structural and chemical parameters. This strategy has been demonstrated mostly for single component nanomaterials. In the present work, we report the gelation of colloidal NC solutions driven by the electrostatic interaction of oppositely charged NCs. A key step for leading this strategy to success is to produce a stable colloidal solution of the positively charged component...
July 17, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Lourdes Bazán-Díaz, Rubén Mendoza-Cruz, J Jesus Velazquez-Salazar, Germán Plascencia-Villa, Francisco Miguel Ascencio-Aguirre, Raul Herrera-Becerra, Hiram Joazet Ojeda-Galván, Grégory Guisbiers, Miguel José Yacamán
We report an efficient wet-chemical production of self-assembled gold-copper bimetallic nanoparticles (diameter of ~2 nm) into two-dimensional flexible ribbon-like nanostructures. A direct observation of a layered arrangement of particles into the nanoribbons was provided through high-resolution transmission electron microscopy and electron tomography. These nanoribbons showed photoluminesce and an efficient photocatalytic activity for the conversion of 4-nitrophenol. Their thermal stability of the nanoribbons was also measured by in situ heating treatment in the electron microscope, confirming that the self-assembled gold-copper nanoribbons efficiently supported up to 350 °C...
July 16, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Jianyu Liu, Xinxin Wang, Wenke Zhang
The studies on the nucleic acid structure and the interactions between nucleic acid and its binding molecules are of great importance for the understanding and controlling of many important biological processes. Atomic force spectroscopy (AFM) imaging is one of the most efficient methods to disclose the DNA structure and binding modes between DNA and DNA-binding molecules. Long-chain DNA tends to form a random coiled structure, which prevents the direct AFM imaging observation of subtle structure formed by DNA itself or protein binding...
July 16, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Hacer Yalcinkaya, Artem Feoktystov, Michael Gradzielski
Self-assembled structures in aqueous solutions can be fixed by polymerization after adding hydrophobic monomers and can thereby be used as templates which allows to substantially alter the properties of these systems. In this work, we started from a self-assembled micellar system consisting of the nonionic surfactants tetradecyldimethylamine oxid (TDMAO) and Pluronic L35 to which styrene was added as a polymerizable monomer. Interestingly, it was observed that styrene induces a transition from micelles to well-defined vesicles in a similar manner as a typical cosurfactant...
July 16, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Charles Smith, Jian Ren Lu, Ian M Tucker, David Grainger, Peixun Li, John Robert Peter Webster, Robert K Thomas
Surface compositions of adsorbed monolayers at the air/water interface, formed from binary surfactant mixtures in equilibrium, have been studied using neutron reflectivity at three discrete temperatures: 10 oC, 25 oC, and 40 oC. The binary compositions studied are SLES EO3/C12En, where n = 6 and 8, at a fixed concentration of 2mM with and without the addition of 0.1M NaCl. Without NaCl, the nonionic surfactant dominates at the interface and non-ideal mixing behaviour is observed. This is modelled using the pseudo phase approximation with a quadratic expansion of the free energy of mixing...
July 16, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Koushik Sarkar, Parthasarathi Dastidar
No abstract text is available yet for this article.
July 16, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Soha T Algoul, Sanghamitra Sengupta, Thomas Tom Bui, Luis Velarde
We report direct spectroscopic measurements of the macromolecular organization of ionic surfactants on the surface of semiconducting single-walled carbon nanotubes (SWCNTs) within solution-processed thin films. By using vibrational sum frequency generation (VSFG) spectroscopy, sensitive measurements of interfacial surfactant ordering were obtained as a function of surfactant concentration for sodium dodecyl sulfate (SDS) encapsulated (6,5) and (7,6) SWCNTs with and without excess electrolytes. Anionic surfactants are known to effectively stabilize SWCNTs...
July 14, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Evan Lowry, Mohammad Piri
It is well accepted that nanopore size is a controlling parameter in determining the phase behavior of confined adsorbate molecules. Despite this knowledge, the quantitative effect of surface chemistry on the confined phase behavior is a factor that remains obfuscated. Obtaining a complete understanding of the variables controlling confined phase behavior is a critical step in developing more complete equations of state for predictive modeling. To this end, a combined experimental and molecular modeling study was conducted to investigate the effects of surface chemistry and wetting on the confined phase behavior of propane and n-butane in modified and unmodified silica MCM-41...
July 14, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Qiang Su, Stephan Vogt, Gilbert Nöll
In this work the hybridization and dehybridization of ssDNA with 20 bases at gold coated sensor surfaces modified with complementary 20 bases capture probe ssDNA was investigated at 18°C by quartz crystal microbalance measurements with dissipation monitoring (QCM-D). A sequence of 20 base pairs with a melting temperature of about 64 °C was chosen, since in many biosensor studies the target molecules are DNA or RNA oligomers of similar length. It turned out that at the applied experimental conditions the DNA hybridization was irreversible, and therefore the hybridization and dehybridization process could not be described by the Langmuir model of adsorption...
July 13, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Jordi Cabanas-Danés, Ellie Landman, Jurriaan Huskens, Marcel Karperien, Pascal Jonkheijm
Release of growth factors while simultaneously maintaining their full biological activity over a period of days to weeks is an important issue in controlled drug delivery and in tissue engineering. In addition, the selected strategy to immobilize growth factors largely determines their biological activity. Silica surfaces derivatized with glycidyl propyl trimethoxysilane yielded epoxide-functionalized surfaces onto which human bone morphogenetic protein-6 (hBMP-6) was immobilized giving stable alkyl amine bonds...
July 13, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Jun Zhang, Wanni Wang, Mengli Zhao, Chenyang Zhang, Chenxi Huang, Sheng Cheng, Hongmei Xu, Haisheng Qian
Magnetically recyclable photocatalyst has drawn considerable research interest due to its importance for practical applications. Herein we demonstrate a facile hydrothermal process to fabricate magnetic core-shell microspheres of Fe3O4@ZnxCd1-xS successfully using Fe3O4@ZnS core-shell microspheres as sacrificed templates. The as-prepared magnetically recyclable photocatalysts show efficient photochemical reduction of Cr(VI) under irradiation of visible light. The photochemical reduction mechanism has been studied to illustrate the reduction-oxidation ability of the photo-generated electrons (e-) and holes (h+); which play an important role in reduction of Cr(VI) to Cr(III) and oxidation of organic dyes...
July 13, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Mingming Gao, Gangyao Wen, Liang Wang
Langmuir monolayers and Langmuir-Blodgett (LB) films of a symmetric diblock copolymer polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) were characterized by the film balance technique and tapping mode atomic force microscopy (AFM), respectively. Effects of both the spreading solution concentration and the surface concentration on the aggregation behavior of PS-b-PMMA at the air/water interface and the morphologies of its LB films were studied in detail. When the monolayers spread in different concentrations (≤0...
July 13, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Diego Coglitore, Nicoletta Giamblanco, Agne Kizalaite, Pierre-Eugene Coulon, Benoit Charlot, Jean-Marc Janot, Sebastien Balme
The understanding of the interactions between nanomaterials, biomolecules and polyphenols is fundamental in food chemistry, toxicology and new emerging fields such as nanomedicine. Here we investigated the effect of the resveratrol, a principal actor in drug delivery application on the interaction between BSA, employed as a vector for the delivery of polyphenol drugs, and gold nanoparticle (gNP), the most promising tool in theranostic applications. Through a combination of experimental techniques, which includes an initial evaluation by dynamic light scattering and surface plasmon resonance spectroscopy, we were able to evaluate the evolution of the gold nanoparticle aggregation with increasing ionic strength and the consequences of the BSA and resveratrol addition...
July 13, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Antoine Venault, Yung Chang
Zwitterionic materials are the latest generation of materials for nonfouling interfaces and membranes. They outperform poly(ethylene glycol)-derivatives because they form tighter bonds with water molecules and can trap more water molecules. This feature article summarizes our laboratory's fundamental developments related to the functionalization of interfaces and membranes using zwitterionic materials. Our molecular designs of zwitterionic polymers and copolymers, sulfobetaine-based, carboxybetaine-based or phosphobetaine-based are first reviewed...
July 13, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Tatsuro Goda, Yuji Miyahara
Conferring antifouling properties can extend the use of conducting polymers in biosensors and bioelectronics under complex biological conditions. On the basis of the antifouling properties of a series of zwitterionic polymers, we synthesized new thiophene-based compounds bearing a phosphorylcholine, carboxybetaine, or sulfobetaine pendant group. The monomers were synthesized by a facile reaction of thiol-functionalized 3,4-ethylenedioxythiophene with zwitterionic methacrylates. Electrochemical copolymerization was performed to deposit zwitterionic poly (3,4-ethylenedioxythiophene) (PEDOT) films with tunable conducting and antifouling properties on a conducting substrate...
July 13, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Chenggan Zhu, Meng Wang, Jinyi Dong, Chao Zhou, Qiangbin Wang
Arraying noble metal nanoparticles at the nanoscale features an important way towards plasmonic devices with novel optical properties such as plasmonic chiral metamolecules, optical waveguides, etc. Along with top-down methods of fabricating plasmonic nanostructures, solution-based self-assembly provides an alternative approach. There are mainly two routes of organizing metal nanoparticles via self-assembly. One is directly linking nanoparticles through some linker molecules, while the other one is decorating nanoparticles on a pre-formed template...
July 12, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Lei Chen, Biwu Liu, Zhang-Run Xu, Juewen Liu
Selective extraction of a small amount of nucleic acids from complex biological samples containing a high concentration of proteins is critical for bioanalytical chemistry. A number of previously published studies have focused on long, double-stranded DNA such as plasmid DNA. On the other hand, we are interested in short oligonucleotides. Nucleic acids have a negatively charged phosphate backbone that interacts with metal oxides strongly, and this may be used to distinguish them from proteins. In this work, a few metal oxide nanoparticles were screened including NiO, CoO, ZnO, TiO2, CeO2, and Fe3O4 for DNA recovery...
July 12, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
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