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Langmuir: the ACS Journal of Surfaces and Colloids

Thiago Sousa, Thales Fernando Damasceno Fernandes, Matheus J S Matos, Eduardo Nery Duarte Araujo, Mario S C Mazzoni, Bernardo R A Neves, Flávio Plentz
The association of organic molecules with 2D materials, creating hybrid systems with mutual influences, constitutes an important testbed for both basic science self-assembly studies and perspective applications. Following this concept, in this work, we show a rich phenomenology that is involved in the interaction of thionine with graphene, leading to a hybrid material formed by well-organized self-assembled structures atop graphene. This composite system is investigated by atomic force microscopy, electric transport measurements, and first principles calculations, which show: 1) an interesting time evolution of thionine self-assembled structures atop graphene; 2) the final molecular assembly is highly oriented (in accordance with the underlying graphene surface symmetry); and 3) thionine introduces a strong n-type doping effect in graphene...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Claudia Kästner, Linda Böhmert, Albert Braeuning, Alfonso Lampen, Andreas F Thünemann
Silver nanoparticles are among the most widely used und produced nanoparticles. Due to their frequent application in consumer products, the assessment of their toxicological potential has seen a renewed importance. A major difficulty is the traceability of nanoparticles in in vitro and in vivo experiments. Even if the particles are labeled, for example by a fluorescent marker, the dynamic exchange of ligands often prohibits their spatial localization. Our study provides an insight into the adsorption and desorption kinetics of two different fluorescent labels on silver nanoparticles with a core radius of 3 nm by dynamic light scattering (DLS), small-angle X-ray scattering (SAXS) and fluorescence spectroscopy...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Minggan Li, Dehi Joung, Dae Kun Hwang
Environment responsive hydrogel structures are of great interests in materials research and have a wide range of applications. By using a flow lithography technique, we report a one-step and high throughput fabrication method for the synthesis of highly pH-responsive hydrogels with designed shape transformations. In this method, heterogeneous hydrogels with porous and nonporous layers are synthesized using a single UV exposure in a microfluidic channel. During the UV polymerization the porous layers, which are formed by using polymerization induced phase separation (PIPS), significantly increase the swelling capability and enhance the swelling rate of the hydrogels...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Andrei Kolesnikov, Nikolaj Georgi, Yury A Budkov, Jens Möllmer, Jorg Hofmann, Juergen Adolphs, Roger Gläser
We present a new model of adsorption-induced deformation of mesoporous solids. The model is based on a simplified version of Local Density Functional Theory in the framework of solvation free energy. Instead of density, which is treated as constant here, we used the film thickness and pore radius as order parameters. This allows us to obtain a self-consistent system of equations describing simultaneously the processes of gas adsorption and adsorbent deformation, as well as conditions for capillary condensation and evaporation...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Shenglong Liao, Yi Tao, Wenbin Du, Yapei Wang
Generation of uniform droplets has been extensively investigated owing to its profound potentials both in scientific research and engineering applications. Although various methods have been put forward to expand this area, new innovations are still needed to improve the technical convenience and save instrumental cost. In this feature article, we highlight an Interfacial Emulsification technique that we developed in the past several years. This technique serves as a platform for preparing uniform droplets that are formed on the air-liquid interface of the continuous phase based on interfacial shearing...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Elizabeth Peterson, Christine Joseph, Hannah Peterson, Rachael Bouwman, Shengzhuang Tang, Jayme Cannon, Kumar Sinniah, Seok Ki Choi
Multivalent ligand-receptor interaction provides the fundamental basis for the hypothetical notion that high binding avidity relates to the strong force of adhesion. Despite its increasing importance in the design of targeted nanoconjugates, an understanding of the physical forces underlying the multivalent interaction remains a subject of urgent investigation. In this study, we designed three vancomycin (Van)-conjugated dendrimers G5(Van)n (n = mean valency = 0, 1, 4) for bacterial targeting with generation 5 (G5) poly(amidoamine) dendrimer as a multivalent scaffold, and evaluated both their binding avidity and physical force of adhesion to a bacterial model surface by employing surface plasmon resonance (SPR) spectroscopy and atomic force microscopy (AFM)...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Dusana Trelova, Alice Rita Salgarella, Leonardo Ricotti, Guido Giudetti, Annarita Cutrone, Petra Sramkova, Anna Zahoranova, Dusan Chorvat, Daniel Hasko, Claudio Canale, Silvestro Micera, Juraj Kronek, Arianna Menciassi, Igor Lacik
Minimizing the foreign body reaction to polyimide-based implanted devices has a pivotal role for several biomedical applications. In this work we propose materials exhibiting non-biofouling properties and a Young's modulus reflecting the one of soft human tissues. We describe the synthesis, characterization and in vitro validation of poly(carboxybetaine) hydrogel coatings covalently attached to polyimide substrates via a photolabile 4-azidophenyl group, incorporated in poly(carboxybetaine) chains at two concentrations of 1...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Fang Cheng, Chuanlei Zhu, Wei He, Jing Zhao, Jingping Qu
Two types of zwitterionic polymer-modified magnetic nanoparticles (NPs) are fabricated by conjugating pSBMA onto PEI-precoated NPs via either one-step method (1S NPs) or two-step method (2S NPs). For both methods, divinyl sulfone is used as linker molecule. Although 1S NPs were capable of resisting both IgG and BSA, 2S NPs exhibited specificity toward IgG adsorption in complex biological fluids, e.g. mixture of serums and IgG. The moderate interactions (Kd ~1.2 µM) between IgG and 2S NPs are three orders of magnitude lower than IgG binding with Protein A (Kd 10nM)...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
K S Shalini Devi, Sharu Jacob, Annamalai Senthil Kumar
Owing to the versatility and biocompatibility, a self-polymerized DA (in presence of air at pH 8.5 tris buffer solution) as a polydopamine (pDA) film has been used for a variety of applications. Indeed, instability under electrified condition (serious surface-fouling) and structural ambiguity of the pDA have been found to be unresolved problems. Previously, pDA films (has hygroscopic and insoluble property) prepared by various controlled chemical oxidation methods have been examined for the structural analysis using ex-situ solid-state NMR and Mass Spectroscopic techniques...
May 24, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Stanislav Jelavić, A Rath Nielsen, S L S Stipp, N Bovet
The interfacial free energy of a solid, which determines its adsorption properties, depends on interactions between the surface and the fluid. A change in surface composition can completely change the behaviour of the solid. Decades of work have explored adsorption and its effects at solid-fluid interfaces from the macroscopic perspective and using molecular modelling so the concept of the electric double layer (EDL) is well established in the community. However, direct, molecular level, experimental observations of the composition within the interface region, and its change with time and conditions, is not abundant...
May 23, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Sabine Wagner, Carlos Zapata, Wei Wan, Kornelia Gawlitza, Marcus Weber, Knut Rurack
Small-molecule oxoanions are often imprinted noncovalently as carboxylates into molecularly imprinted polymers (MIPs), requiring the use of an organic counterion. Popular species are either pentamethylpiperidine (PMP) as a protonatable cation or tetraalkylammonium (TXA) ions as permanent cations. The present work explores the influence of the TXA as a function of their alkyl chain length, from methyl to octyl, using UV/vis absorption, fluorescence titrations and HPLC, as well as MD simulations. Protected phenylalanines (Z-L/D-Phe) served as templates/analytes...
May 23, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Yanfei Tang, Gary S Grest, Shengfeng Cheng
Large scale molecular dynamics simulations for bidisperse nanoparticle suspensions with an explicit solvent are used to investigate the effects of evaporation rates and volume fractions on the nanoparticle distribution during drying. Our results show that "small-on-top" stratification can occur when Pes Φs ≥ c with c ∼ 1, where Pes is the Péclet number and Φs is the volume fraction of the smaller particles. This threshold of Pes Φs for "small-on-top" is larger by a factor of ~ α2 than the prediction of the model treating solvent as an implicit viscous background, where α is the size ratio between the large and small particles...
May 23, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Suguna Perumal, Atchudan Raji, In Woo Cheong
Measurement of the interaction force between two materials provides important information on various properties, such as adsorption, binding or compatibility for coatings, adhesion, and composites. The interaction forces of zwitterionic and ionic monomers with graphite platelets (G) and reduced graphene oxide (rGO) surfaces were systematically investigated using atomic force microscopy (AFM) in air and water. The monomers examined were 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate (MPC), [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SBE), [2-(acryloyloxy)ethyl]trimethylammonium chloride (ATC), and 2-methyl-2-propene-1-sulfonic acid sodium (MSS)...
May 23, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Yasuhiro Kakimoto, Yoshihiro Tachihara, Yoshiaki Okamoto, Keisuke Miyazawa, Takeshi Fukuma, Ryugo Tero
Lipid molecules such as glycolipids which are modified with hydrophilic biopolymers participate in the biochemical reactions occurring on cell membranes. Their functions and efficiency are determined by the formation of microdomains and their physical properties. We investigated the morphology and properties of domains induced by the hydrophilic-polymer-modified lipid applying poly-ethylene glycol (PEG)-modified lipid as a model modified lipid. We formed supported lipid bilayers (SLBs) using a 0-10 mol % range of PEG-modified lipid concentration (CPEG)...
May 23, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Jordi Martínez-Esaín, Josep Ros, Jordi Faraudo, Susagna Ricart, Ramón Yáñez
Here, 15 LnF3 nanocrystals are synthesized using coprecipitation method with citrate stabilization to allow the fast, easy, and reproducible synthesis of several nanoscaled structures in water. General trends related to the behavior of LnF3 nanocrystals are highlighted due to their broad range of application in several fields (e.g., medical applications). The same nature for all Ln3+ cations is expected due to the internal role of f orbitals. However, we found that the use of different lanthanide elements is crucial in the final size, shape, assembly, and crystalline structure...
May 23, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Mihee Kim, Milan Vala, Christopher Ertsgaard, Sang-Hyun Oh, Timothy P Lodge, Frank S Bates, Benjamin J Hackel
Poloxamer 188 (P188), a poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) triblock copolymer, protects cell membranes against various external stresses whereas polyethylene oxide (PEO; 8,600 g/mol) homopolymer lacks protection efficacy. As part of a comprehensive effort to elucidate the protection mechanism, we used surface plasmon resonance (SPR) to obtain direct evidence of binding of the polymers onto supported lipid bilayers. Binding kinetics and coverage of the P188 and PEO were examined and compared...
May 22, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Meenakshi Verma, Navneet Kaur, Narinder Singh
We have designed and synthesized a novel, water-soluble naphthalimide-histidine receptor (1) with excellent fluorescent properties. Functioning of the synthesized receptor was performed through developing their DNA-receptor hybrid assembly (DRHA), which has shown significant changes in the emission profile upon interactions with dipicolinic acid (DPA), a biomarker for Bacillus anthracis spores. DRHA showed fluorescence enhancement upon binding with DPA with the characteristic of internal charge transfer. It is notable that this assembly exhibited a significant limit of detection (12 nM) toward DPA...
May 22, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Robert Kevin Lade, Krystopher S Jochem, Christopher W Macosko, Lorraine F Francis
Capillary flow and drying of polymer solutions in open microchannels are explored over timescales spanning seven orders of magnitude, from capillary filling (10-3 -10 s) to the formation of a dry thin film (a 'capillary coating'; 102 -103 s). During capillary filling, drying-induced changes (increased solids content and viscosity) generate micro-scale pinning events that impede contact line motion. Three unique types of pinning are identified and characterized, each defined by the specific location(s) along the contact line at which pinning is induced...
May 22, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Ti-Wei Chen, Zhong-Qiu Li, Kang Wang, Feng-Bin Wang, Xing-Hua Xia
A novel and efficient photochemical method has been proposed for the encapsulation of Prussian blue nanoparticles (PBNPs) inside the channels of carbon nanotubes (PB-in-CNTs) in an acidic ferrocyanide solution under UV/Vis illumination and the confinement effect of CNTs on the electrochemical properties of PBNPs is systematically explored. PB-in-CNTs shows a faster electron transfer process, an enhanced electrocatalytic activity toward the reduction of H2O2 and an increased anti-base ability compared to PBNPs loaded outside of CNTs (PB-out-CNTs)...
May 22, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Luan Nguyen, Paul Pengcheng Tao, Huimin Liu, Mohamed Al-Hada, Matteo Amati, Hikmet Sezen, Luca Gregoratti, Yu Tang, Stephen D House, Franklin Feng Tao
For nanoparticles active for chemical and energy transformations in liquid environment, chemistries of surface or near-surface regions of these catalyst nanoparticles in liquid are crucial for fundamentally understanding their catalytic performances at a molecular level. Compared to catalysis at a solid-gas interface, there is very limited information on surface of these catalyst nanoparticles under working condition or during catalysis. Photoelectron spectroscopy is a surface-sensitive technique; however, it is challenging to study the surfaces of catalyst nanoparticles dispersed in liquid due to the short inelastic mean free path of photoelectrons travelling in liquid...
May 22, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
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