Higher-order mesoscopic self-assembly of fluorinated surfactants on water surfaces

Surfactants containing fluorocarbon chains have been increasingly studied because they self-assemble into a variety of microscopic and mesoscopic domains and tend to form highly ordered patterns at the air/water interface; these patterns are clearly different from those formed by their hydrocarbon analogs. Focusing on the fluorinated surfactants possessing unique physical characteristics, this review describes the relationship between the line tension and dipole interaction, which is the comprehensive principle governing the pattern formation of two-dimensional self-assemblies. This review further discusses several key experimental and analytical techniques that are useful for characterizing the shape, size, correlation, and viscoelasticity of hierarchical self-assemblies on water surfaces. Finally, several biomedical applications, including biomimetic surface coating, multimodal contrast agents in medical diagnostics, and controlled delivery of gases (O₂ and NO) for oxygenation and antimicrobial effects, are introduced to highlight how the unique physicochemical properties of fluorinated self-assemblies can be applied in materials science

Metallo-solid lipid nanoparticles as colloidal tools for meso-macroporous supported catalysts

Meso–macroporous silica containing iron oxide nanoparticles (15–20 nm) was synthesized by formulating solid lipid nanoparticles and metallosurfactant as both template and metal source. Because of the high active surface area of the catalyst, the material exhibits an excellent performance in a Fenton-like reaction for methylene blue (MB) degradation, even at low amount of iron oxide (5% TOC after 14 h)

Spin State As a Probe of Vesicle Self-Assembly

International audienceA novel system of paramagnetic vesicles was designed using ion pairs of iron-containing surfactants. Unilamellar vesicles (diameter approximate to 200 nm) formed spontaneously and were characterized by cryogenic transmission electron microscopy, nanoparticle tracking, analysis, and light and small-angle neutron scattering. Moreover, for the first time, it is shown that magnetization measurements can be used to investigate self-assembly of such functionalized systems, giving information on the vesicle compositions and distribution Of surfactants between the bilayers and the aqueous bulk

Tailored Jeffamine molecular tools for ordering mesoporous Silica

Herein, we report the formation of organized mesoporous silica materials prepared from a novel nonionic gemini surfactant, myristoyl-end capped Jeffamine, synthesized from a polyoxyalkyleneamine (ED900). The behavior of the modified Jeffamine in water was first investigated. A direct micellar phase (L1) and a hexagonal (H1) liquid crystal were found. The structure of the micelles was investigated from the SAXS and the analysis by Generalized Indirect Fourier Transformation (GIFT), which show that the particles are globular of coreshell type. The myristoyl chains, located at the ends of the amphiphile molecule are assembled to form the core of the micelles and, as a consequence, the molecules are folded over on themselves. Mesoporous materials were then synthesized from the self-assembly mechanism. The recovered materials were characterized by SAXS measurements, nitrogen adsorptiondesorption analysis, transmission and scanning electron microscopy. The results clearly evidence that by modifying the synthesis parameters, such as the surfactant/silica precursor molar ratio and the hydrothermal conditions, one can control the size and the nanostructuring of the resulting material. It was observed that, the lower the temperature of the hydrothermal treatment, the better the mesopore ordering

Solubilization of decane into gemini surfactant with a modified Jeffamine backbone: Design of hierarchical porous silica

Herein, we have investigated the solubilization of decane into a novel nonionic gemini surfactant, myristoyl-end capped Jeffamine, synthesized from a polyoxyalkyleneamine (ED900). Starting from this system, porous silica materials have been prepared. Performing the hydrothermal treatment at low temperature, a slight increase of the mesopore diameter is observed in the presence of decane. Increasing the temperature of the hydrothermal treatment, no swelling effect of decane is detected. By contrast, the pore diameter decreases but better mesopore homogeneity and a larger wall thickness are obtained. At high decane concentration the new myristoyl-end capped Jeffamine/decane/water system forms oil-in-water emulsions, which are used as template for the formation of hierarchical porous silica materials

Modelling the effects of E/Z photoisomerization of a cyclocurcumin analogue on the properties of cellular lipid membranes

The use of photosensitive molecules capable of isomerizing under light stimuli, and thus induce perturbation in biological systems, is becoming increasingly popular for potential light-activated chemotherapeutic purposes. We recently show that a cyclocurcumin derivative (CCBu), may be suitable for light-activated chemotherapy and may constitute a valuable alternative to traditional photodynamic therapy, due to its oxygen-independent mechanism of action, which allows the treatment of hypoxic solid tumors. In particular, we have shown that the E/Z photoisomerization of CCBu correlates with strong perturbations of model lipid bilayers. In this work, we perform all-atom classical molecular dynamics for a more complex bilayer, whose composition is, thus, much closer to eukaryotic outer cell membranes. We have evidenced important differences in the interaction pathway between CCBu and the complex lipid bilayer as compared to previous models, concerning both the membrane penetration capacity and the isomerization-induced perturbations. While we confirm that structural perturbations of the lipid membrane are induced by isomerization, we also show how the use of a simplified membrane model can result in an oversimplification of the system and hinder key physical and biological phenomena. Although, CCBu may be considered as a suitable candidate for light-activated chemotherapy, we also underline how the inclusion of bulkier substituents, inducing larger perturbations upon photoisomerization, may enhance its efficiency

Effect of morphology and hydrophobization of MoS2 microparticles on the stability of poly-α-olefins lubricants

International audienceThe use of MoS ⁠ 2 nanoparticles as additive to lubricating oils is restricted by their low stability in oily media, which limits their use despite the enormous benefits associated with their intrinsic properties in terms of reduction of friction and wear coefficients. In this context, we investigated the effect of morphologies (platelets vs spheres) and surface functionalization of nanoparticles on the stability of their suspensions in poly-α-olefins (PAO) with various viscosities, which are base oils used in wind turbines. The particles were characterized by XRD, FTIR, scanning electron microscopy, atomic force microscopy and dynamic light scattering, and the stability of the resultant formulations was followed by optical (non-contact) measurements. It was found that the dispersions had similar stability despite the larger size of platelet-like particles compared to spherical ones (1-5 μm vs 600-800 nm). The dispersibility could be increased through grafting of alkylsilane on the surface defects (the longer the alkyl chain, the more stable the formulation) and with the increase of the oil kinematic viscosity (from 34 to 1705 cps at 25 °C)

Curcumin and Cyclocurcumin-based Derivatives as Potential Candidates for Photocontrolled Treatment

Cyclocurcumin is a natural compound extracted from turmeric and showing an interestingsolvent-dependent photoswitching ability. The solvent-dependent photochemistry ofcyclocurcumin has been rationalized on the basis of a competition between -* and n-*states.1 Furthermore, we have reported the synthesis of a biomimetic analogue showingenhanced photochemical properties and in particular presenting photoswitching capacity invarious media.2 In addition, molecular modeling and simulation, including density functionaland wavefunction based methods were used to explore the excited states potential energysurface landscape. We realize that with cyclocurcumin, the addition of a carbon-carbondouble bond to the core of the natural compound favors the population of the -* state,whatever the choice of the solvent, and hence leads to photoisomerization, with fluorescencereduced to only a minor channel comparing with natural derivative.3 In addition, the two-photon absorption (TPA) cross section is also strongly increased compared to the parentcompound, paving the way to the use in biologically oriented applications. Apart of that, weare also interested in the interaction between these systems and lipidic membranes as apotential photocontrolled way to destabilize it, which can yield in cellular apoptosis or vesicledrug delivery. Likewise, natural curcumin was studied as a potential photodynamic therapycandidate taking advantage of it larger TPA comparing with other used drugs

Encapsulation of probiotics: insights into academic and industrial approaches

The natural inhabitants of the gastrointestinal tract play a key role in the maintenance of human health. Over the last century, the changes on the behavior of our modern society have impacted the diversity of this gut microbiome. Among the strategies to restore gut microbial homeostasis, the use of probiotics has received a lot of attention. Probiotics are living microorganisms that promote the host health when administered in adequate amounts. Its popularity increase in the marketplace in the last decade draws the interest of scientists in finding suitable methods capable of delivering adequate amounts of viable cells into the gastrointestinal tract. Encapsulation comes into the scene as an approach to enhance the cells survival during processing, storage and consumption.This paper provides a comprehensive perspective of the probiotic field at present time focusing on the academia and industry scenarios in the past few years in terms of encapsulation technologies employed and research insights including patents. The analysis of the encapsulation technologies considering food processing costs and payload of viable bacteria reaching the gastrointestinal tract would result into successful market novelties. There is yet a necessity to bridge the gap between academia and industry