Surfactant Concentration Regime in Miniemulsion Polymerization for the Formation of MMA Nanodroplets by High-Pressure Homogenization

This article focuses on the adequate surfactant concentration regime in which MMA droplets are stabilized sufficiently against coalescence during high-pressure homogenization but still no diffusion processes from droplets to micelles take place in the polymerization. Monomer miniemulsions with different surfactant concentrations were prepared with different energy inputs. Emulsions result that depend either on the surfactant concentration or on the energy input of the homogenization process. For both cases, the occupancy of the interface is compared as a function of the droplet size. It is shown that the surfactant concentration needed for the stabilization of a specified interface area decreases with increasing droplet size. For the dependence of droplet size on the energy input, it is shown that more surfactant can be applied before emulsion polymerization starts, but the applicable surfactant concentration is lower than the cmc and also depends on droplet size

Origin of life from a maker's perspective -- focus on protocellular compartments in bottom-up synthetic biology

The origin of life is shrouded in mystery, with few surviving clues, obscured by evolutionary competition. Previous reviews have touched on the complementary approaches of top-down and bottom-up synthetic biology to augment our understanding of living systems. Here we point out the synergies between these fields, especially between bottom-up synthetic biology and origin of life research. We explore recent progress made in artificial cell compartmentation in line with the crowded cell, its metabolism, as well as cycles of growth and division, and how those efforts are starting to be combined. Though the complexity of current life is among its most striking characteristics, none of life's essential features require it, and they are unlikely to have emerged thus complex from the beginning. Rather than recovering the one true origin lost in time, current research converges towards reproducing the emergence of minimal life, by teasing out how complexity and evolution may arise from a set of essential components.Comment: 29 pages, 2 figures, 1 tabl

Common trends of global education: educational methods in USA and Russia

This article touches upon the issues of changes in the educational system in the knowledge society. The main purpose of this research is the study of new teaching methods, with due regard to the needs of society and human potential. For this purpose, educational methods of the US and Russia were analyzed and compared, their advantages and disadvantages were estimated, and common trends in the development of education were identified. It is stated that during the formation of innovative methods of education for future generations, it is necessary to take into account ethical standards of each ethnic group, culture and traditions of specific country, as well as psycho-physical standards of students. It is justified that the idea of the creation of unified teaching methods for the entire planet population is impossible due to geographic, ethnic, political, and economic differences of every country. However, according to research results of popular techniques, it is possible to develop a model of the most appropriate educational method for the vast majority of countries with due consideration of constant development of science as the main influence factor on methods of education. It is concluded that the general trends of global education are individualization and humanization. They lead to the formation of flexible, critical, creative and effective thinking of students in terms of variability and uncertainty of social reality

Off/On Fluorescent Nanoparticles for Tunable High-Temperature Threshold Sensing

Herein, a versatile threshold temperature sensor based on the glass transition temperature-triggered fluorescence activation of a dye/developer duo, encapsulated in polymeric nanoparticles is reported. The emission enhancement, detectable even by unaided eye is completed within a narrow temperature range and activates at adjustable threshold temperatures up to 200 °C. Fluorescence is chosen as sensing probe due to its high detection sensitivity together with an advanced spatial and temporal resolution. The strategy is based on nanoparticles prepared from standard thermoplastic polymers, a fluorescence developer, and the commercially available Rhodamine B base dye, a well-known and widely used fluorescent molecule. By making nanoparticles of different thermoplastic polymers, fast, abrupt, and irreversible disaggregation induced fluorescence enhancement, with tunable threshold temperature depending on the nanoparticles polymer glass transition is achieved. As a proof-of-concept for the versatility of this novel family of NPs, their use for sensing the thermal history of environments and surfaces exposed to the threshold temperature is showed

Encapsulation of aqueous-core nanocapsules in PLLA multicompartments microparticles

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Amphiphile-Induced Anisotropic Colloidal Self-Assembly

Spherical colloidal particles typically self-assemble into hexagonal lattices when adsorbed at liquid interfaces. More complex assembly structures, including particle chains and phases with square symmetry, were theoretically predicted almost two decades ago for spherical particles interacting via a soft repulsive shoulder. Here, we demonstrate that such complex assembly phases can be experimentally realized with spherical colloidal particles assembled at the air/water interface in the presence of molecular amphiphiles. We investigate the interfacial behavior of colloidal particles in the presence of different amphiphiles on a Langmuir trough. We transfer the structures formed at the interface onto a solid substrate while continuously compressing, which enables us to correlate the prevailing assembly phase as a function of the available interfacial area. We observe that block copolymers with similarities to the chemical nature of the colloidal particles, as well as the surface-active protein bovine serum albumin, direct the colloidal particles into complex assembly phases, including chains and square arrangements. The observed structures are reproduced by minimum energy calculations of hard core–soft shoulder particles with experimentally realistic interaction parameters. From the agreement between experiments and theory, we hypothesize that the presence of the amphiphiles manipulates the interaction potential of the colloidal particles. The assembly of spherical colloidal particles into complex assembly phases on solid substrates opens new possibilities for surface patterning by enriching the library of possible structures available for colloidal lithography

Social crisis: reflection on the economic, social and educational alternatives from a gender perspective

Colección ReSed. Es un artículo de ReSed Nº 3, perteneciente al monográfico Crisis Social, Educación y Desarrollo Profesional. Coordinación del Monográfico: Dra. Montserrat Vargas Vergara Dirección de ReSed: Dra. A-Beatriz Pérez-GonzálezEn el presente artículo hacemos una reflexión sobre cómo la actual crisis financiera plantea una crisis de valores, que nos lleva a la necesidad de reorganización en lo económico, social y educativo. La interpretación del problema la hacemos desde un posicionamiento de estudio de género, donde veremos cómo el feminismo traza alternativas viables. Las perspectivas de la economía feminista o economía del bien común son algunas de las alternativas que vamos a reflejar, al mismo tiempo que describimos una realidad condicionada por el género, no siempre asumida por los gobernantes. La propuesta que surge de esta reflexión está basada en el cuidado equilibrado de todos los miembros de la sociedad, promoviendo una educación igualitaria y más libre entre los géneros; nuevos caminos que se hacen necesarios para construir una sociedad más equitativa y sostenible y que favorezcan el desarrollo personal, social y laboral de todos sus miembros

Comblike ionic complexes of hyaluronic acid and alkanoylcholine surfactants as a platform for drug delivery systems

Nontoxic alkanoylcholine soaps (nACh) were synthesized from choline and fatty acids with numbers of carbons n equal to 12, 14, 16, and 18, the latter including both saturated and 9-cis unsaturated alkanoyl chains. Coupling of nACh with hyaluronic acid (HyA) rendered comblike ionic complexes nACh·HyA that were non-water-soluble. The complexes were thermally stable up to temperatures above 200 °C but readily degraded by water, in particular when hyaluronidases were present in the aqueous medium. In the solid state, these complexes were selfassembled in a biphasic layered structure in which the surfactant and the polysaccharide phases were alternating regularly with a periodicity dependent on the length of the alkanoyl chain. The paraffinic phase was found to be crystallized in saturated complexes with n = 14, but only 18ACh·HyA showed reversible melting crystallization when subjected to cyclic heating-cooling treatment. Nanoparticles with diameters in the 50-150 nm range were prepared by ionotropic gelation from unbalanced 18ACh·HyA complexes with surfactant:HyA ratios of 0.5 and 0.25. These nanoparticles were also structured in layers, swelled slowly in water, and shown to be noncytotoxic in in vitro assays against macrophages cells. It was also shown that the anticancer drug doxorubicin was efficiently encapsulated in both films and NPs of 18ACh·HyA, and its release was shown to be almost linear and complete after one day of incubation in physiological medium. The nACh·HyA complexes constitute a highly promising biocompatible/biodegradable platform for the design of systems suitable for drug transport and targeting delivery in anticancer chemotherapy.Peer ReviewedPostprint (author's final draft

Labeling of mesenchymal stromal cells with iron oxide-poly(l-lactide) nanoparticles for magnetic resonance imaging: uptake, persistence, effects on cellular function and magnetic resonance imaging properties

Background aims. Mesenchymal stromal cells (MSC) are the focus of research in regenerative medicine aiming at the regulatory approval of these cells for specific indications. To cope with the regulatory requirements for somatic cell therapy, novel approaches that do not interfere with the natural behavior of the cells are necessary. In this context in vivo magnetic resonance imaging (MRI) of labeled MSC could be an appropriate tool. Cell labeling for MRI with a variety of different iron oxide preparations is frequently published. However, most publications lack a comprehensive assessment of the noninterference of the contrast agent with the functionality of the labeled MSC, which is a prerequisite for the validity of cell-tracking via MRI. Methods.We studied the effects of iron oxide-poly(L-lactide) nanoparticles in MSC with flow cytom-etry, transmission electron microscopy (TEM), confocal laser scanning microscopy (CLSM), Prussian blue staining, CyQuant® proliferation testing, colony-forming unit-fibroblast (CFU-F) assays, flow chamber adhesion testing, immuno-logic tests and differentiation tests. Furthermore iron-labeled MSC were studied by MRI in agarose phantoms and Wistar rats. Results. It could be demonstrated that MSC show rapid uptake of nanoparticles and long-lasting intracellular persistence in the endosomal compartment. Labeling of the MSC with these particles has no influence on viability, differentiation, clonogenicity, proliferation, adhesion, phenotype and immunosuppressive properties. They show excellent MRI properties in agarose phantoms and after subcutaneous implantation in rats over several weeks. Conclusions. These particles qualify for studying MSC homing and trafficking via MRI