Particles adsorbed at various non-aqueous liquid-liquid interfaces

Particles adsorbed at liquid interfaces are commonly used to stabilise water-oil Pickering emulsions and water-air foams. The fundamental understanding of the physics of particles adsorbed at water-air and water-oil interfaces is improving significantly due to novel techniques that enable the measurement of the contact angle of individual particles at a given interface. The case of non-aqueous interfaces and emulsions is less studied in the literature. Non-aqueous liquid-liquid interfaces in which water is replaced by other polar solvents have properties similar to those of water-oil interfaces. Nanocomposites of non-aqueous immiscible polymer blends containing inorganic particles at the interface are of great interest industrially and consequently more work has been devoted to them. By contrast, the behaviour of particles adsorbed at oil-oil interfaces in which both oils are immiscible and of low dielectric constant (ε < 3) is scarcely studied. Hydrophobic particles are required to stabilise these oil-oil emulsions due to their irreversible adsorption, high interfacial activity and elastic shell behaviour

Tuning the bulk behavior and 2D interfacial self-assembly of microgels by Keggin-type polyoxometalate ionic specificity

Finding new ways to tune the behavior of thermoresponsive microgels in bulk and confined at 2D liquid interfaces is key to achieve a deeper understanding and control of these smart materials. We studied the interaction of positively charged pNIPAM microgels with the Keggin-type polyoxometalate $Na_{3}PW_{12}O_{40}$ (POM). In bulk, we observed charge inversions below and above the volume phase transition temperature (VPTT) at significantly low POM concentrations as $5\cdot10^{-5}$ M. In the presence of POM, the microgels exhibited a deswelling-swelling-deswelling behaviour below the VPTT, and a two-step further deswelling above the VPTT. When microgels were confined at 2D water/air interfaces, adding $10^{-5}$ M of POM below the VPTT was equivalent to heat above the VPTT and compress the monolayer from $5$ to 20\,\text{mN m^{-1}}. Above the VPTT, the diameter at the interface did not change while the portion immersed in the subphase further deswelled, in agreement with the behavior in bulk. Adding more POM did not change the diameter at the interface nor the height of the microgels, showing a saturation effect in 2D. The restructuring of the pNIPAM polymeric network by the POM was characterized by EDS mapping and XPS. The microgel monolayers with POM improved their resistance to plasma etching, which could be useful for soft colloidal lithography

Microgels Adsorbed at Liquid-Liquid Interfaces: A Joint Numerical and Experimental Study

Soft particles display highly versatile properties with respect to hard colloids, even more so at fluid-fluid interfaces. In particular, microgels, consisting of a cross-linked polymer network, are able to deform and flatten upon adsorption at the interface due to the balance between surface tension and internal elasticity. Despite the existence of experimental results, a detailed theoretical understanding of this phenomenon is still lacking due to the absence of appropriate microscopic models. In this work, we propose an advanced modelling of microgels at a flat water/oil interface. The model builds on a realistic description of the internal polymeric architecture and single-particle properties of the microgel and is able to reproduce its experimentally observed shape at the interface. Complementing molecular dynamics simulations with in-situ cryo-electron microscopy experiments and atomic force microscopy imaging after Langmuir-Blodgett deposition, we compare the morphology of the microgels for different values of the cross-linking ratios. Our model allows for a systematic microscopic investigation of soft particles at fluid interfaces, which is essential to develop predictive power for the use of microgels in a broad range of applications, including the stabilization of smart emulsions and the versatile patterning of surfaces

Self-Templating Assembly of Soft Microparticles into Complex Tessellations

Self-assembled monolayers of microparticles encoding Archimedean and non-regular tessellations promise unprecedented structure-property relationships for a wide spectrum of applications in fields ranging from optoelectronics to surface technology. Yet, despite numerous computational studies predicting the emergence of exotic structures from simple interparticle interactions, the experimental realization of non-hexagonal patterns remains challenging. Not only kinetic limitations often hinder structural relaxation, but also programming the inteparticle interactions during assembly, and hence the target structure, remains an elusive task. Here, we demonstrate how a single type of soft polymeric microparticle (microgels) can be assembled into a wide array of complex structures as a result of simple pairwise interactions. We first let microgels self-assemble at a water-oil interface into a hexagonally packed monolayer, which we then compress to varying degrees and deposit onto a solid substrate. By repeating this process twice, we find that the resultant structure is not the mere stacking of two hexagonal patterns. The first monolayer retains its hexagonal structure and acts as a template into which the particles of the second monolayer rearrange to occupy interstitial positions. The frustration between the two lattices generates new symmetries. By simply varying the packing fraction of the two monolayers, we obtain not only low-coordination structures such as rectangular and honeycomb lattices, but also rhomboidal, hexagonal, and herringbone superlattices which display non-regular tessellations. Molecular dynamics simulations show that these structures are thermodynamically stable and develop from short-ranged repulsive interactions, making them easy to predict, and thus opening new avenues to the rational design of complex patterns

Sequential capillarity-assisted particle assembly in a microfluidic channel

The authors acknowledge support from an ETH Research Grant ETH-15 17-1 (R. S.), from an ETH Postdoctoral Fellowship FEL-21 15-2 and SNSF PRIMA Grant 179834 (E. S.), from a Postdoctoral fellowships programme “Beatriu de Pinós”, funded by the Secretary of Universities and Research (Government of Catalonia) and by the Horizon 2020 programme of research and innovation of the European Union under the Marie Sklodwoska-Curie grant agreement no. 801370 (Grant 2018 BP 00029) (M. A. F. R.) and from a Gordon and Betty Moore Foundation Investigator Award on Aquatic Microbial Symbiosis (grant GBMF9197) (R. S.). The authors thank Dr. Heiko Wolf at IBM Research Zurich for insightful discussions.Colloidal patterning enables the placement of a wide range of materials into prescribed spatial arrangements, as required in a variety of applications, including micro- and nano-electronics, sensing, and plasmonics. Directed colloidal assembly methods, which exploit external forces to place particles with high yield and great accuracy, are particularly powerful. However, currently available techniques require specialized equipment, which limits their applicability. Here, we present a microfluidic platform to produce versatile colloidal patterns within a microchannel, based on sequential capillarity-assisted particle assembly (sCAPA). This new microfluidic technology exploits the capillary forces resulting from the controlled motion of an evaporating droplet inside a microfluidic channel to deposit individual particles in an array of traps microfabricated onto a substrate. Sequential depositions allow the generation of a desired spatial layout of colloidal particles of single or multiple types, dictated solely by the geometry of the traps and the filling sequence. We show that the platform can be used to create a variety of patterns and that the microfluidic channel easily allows surface functionalization of trapped particles. By enabling colloidal patterning to be carried out in a controlled environment, exploiting equipment routinely used in microfluidics, we demonstrate an easy-to-build platform that can be implemented in microfluidics labs.ETH Research Grant ETH-15 17-1ETH Postdoctoral Fellowship FEL-21 15-2SNSF PRIMA Grant 179834Postdoctoral fellowships programme "Beatriu de Pinos" - Government of CataloniaHorizon 2020 programme of research and innovation of the European Union under the Marie Sklodwoska-Curie grant 801370 2018 BP 00029Gordon and Betty Moore Foundation Investigator Award on Aquatic Microbial Symbiosis GBMF919

Feedback-Controlled Active Brownian Colloids with Space-Dependent Rotational Dynamics

The non-thermal nature of self-propelling colloids offers new insights into non-equilibrium physics. The central mathematical model to describe their trajectories is active Brownian motion, where a particle moves with a constant speed, while randomly changing direction due to rotational diffusion. While several feedback strategies exist to achieve position-dependent velocity, the possibility of spatial and temporal control over rotational diffusion, which is inherently dictated by thermal fluctuations, remains untapped. Here, we decouple rotational diffusion from thermal noise. Using external magnetic fields and discrete-time feedback loops, we tune the rotational diffusivity of active colloids above and below its thermal value at will and explore a rich range of phenomena including anomalous diffusion, directed transport, and localization. These findings add a new dimension to the control of active matter, with implications for a broad range of disciplines, from optimal transport to smart materials

Unraveling the mechanism of TTL genes in cellulose biosynthesis

As sessile organisms, plants require mechanisms to sense and respond to the challenging environment, that encompass both biotic and abiotic factors that results in differential development. In these conditions is essential to balance growth and stress responses. As cell walls shape plant growth, this differential growth response cause alterations to the plant cell wall where cellulose is the major component. Therefore, understanding the mechanisms that regulate cellulose biosynthesis is essential to develop strategies to improve plant production. In Arabidopsis, the TETRATRICOPEPTIDE THIOREDOXIN-LIKE (TTL) gene family is composed by four members (TTL1 to TTL4) and mutations in TTL1, TTL3, and TTL4 genes cause reduced growth under salt and osmotic stress due to defects in plant cell wall integrity. We observe association of TTL3 with most core components in traducing BR signalling, such as LRR-RLK BRI1 or GSK3 BIN2 that modulate cellulose biosynthesis through phosphorylating cellulose synthases. Here, we show that ttl mutants present defects in the plant cell wall, particularly in Isoxaben, salt or sucrose stress. Spinning disk microscopy in etiolated hypocotyls reveals that, TTL proteins are responsible for the cellulose synthase complex (CSC) stability in plasma membrane (PM) upon sucrose stress. Moreover, TTL3 associates with LRR-RLKs that have been shown to be important for cellulose biosynthesis such as FEI1 in the FEI1/FEI2/SOS5 pathway. We aim to investigate the mechanisms by which TTL proteins regulate CesA stability in PM under stress, using a combination of genetics, biochemical, and molecular and cell biology approaches.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. This work was supported by grants from: (1) Ministerio de Ciencia e Innovación BIO2014-55380-R, BIO2014-56153-REDT; (2) Ministerio de Economía, Industria y Competitividad (BES-2015-071256

The role of multimorbidity in short-term mortality of lung cancer patients in Spain: a population-based cohort study

M.A.L.F. received support from the Instituto de Salud Carlos III, Madrid, Spain (grant/award no. CP17/00206-EU-FEDER). This work was supported by the Instituto de Salud Carlos III, Madrid, Spain [EU-FEDER-FIS PI-18/01593], the Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Publica), the Cancer Epidemiological Surveillance Subprogram (VICA) from the Instituto de Salud Carlos III, Madrid, Spain, and the Andalusian Department of Health [PI-0152/2017]. The funders had no role in the design and conduct of the study, data collection, management, analysis, and interpretation of the data, the preparation, review, or approval of the manuscript or the decision to submit the manuscript for publication.Aim: Chronic diseases often occur simultaneously and tend to be associated with adverse health outcomes, but limited research has been undertaken to understand their role in lung cancer mortality. Therefore, this study aims to describe the prevalence and patterns of having one (comorbidity) or ≥ 2 chronic diseases (multimorbidity) among lung cancer patients in Spain, and to examine the association between comorbidity or multimorbidity and short-term mortality risk at six months after cancer diagnosis. Methods: In this population-based cohort study, data were drawn from two Spanish population-based cancer registries, Girona and Granada, and electronic health records. We identified 1259 adult lung cancer patients, diagnosed from 1st January 2011 to 31st December 2012. We identified the most common patterns of individual comorbidities and their pairwise correlations. We used a flexible parametric modelling approach to assess the overall short-term mortality risk 6 months after cancer diagnosis by levels of comorbidity after adjusting for age, sex, smoking status, province of residence, surgery, cancer stage, histology, and body mass index. Results: We found high prevalence of comorbidity in lung cancer patients, especially among the elderly, men, those diagnosed with advanced-stage tumours, smokers, and obese patients. The most frequent comorbidities were chronic obstructive pulmonary disease (36.6%), diabetes (20.7%) and heart failure (16.8%). The strongest pairwise correlation was the combination of heart failure with renal disease (r = 0.20, p < 0.01), and heart failure with diabetes (r = 0.16, p < 0.01). Patients with either one or two or more comorbidities had 40% higher overall mortality risk than those without comorbidities (aHR for comorbidity: 1.4, 95%CI: 1.1–1.7; aHR for multimorbidity: 1.4, 95%CI: 1.1–1.8), when relevant confounding factors were considered. Conclusions: The presence of comorbid diseases, rather than the number of comorbidities, was associated with increasing the risk of short-term lung cancer mortality in Spain. Comorbidity was a consistent and independent predictor of mortality among lung cancer patients, six months after diagnosis. The most common comorbid conditions were age-, obesity- and tobacco-related diseases. Our findings highlight the need to develop targeted preventive interventions and more personalised clinical guidelines to address the needs of lung cancer patients with one or more comorbidities in Spain.Instituto de Salud Carlos III CP17/00206-EU-FEDER EU-FEDER-FIS PI-18/01593Consortium for Biomedical Research in Epidemiology and Public Health (CIBER en Epidemiologia y Salud Publica)Cancer Epidemiological Surveillance Subprogram (VICA) from the Instituto de Salud Carlos III, Madrid, SpainAndalusian Department of Health PI-0152/201