Multiphasic System Research Articles

The molecular basis of cell memory in mammals: The epigenetic cycle.

Cell memory refers to the capacity of cells to maintain their gene expression program once the initiating environmental signal has ceased. This exceptional feature is key during the formation of mammalian organisms, and it is believed to be in part mediated by epigenetic factors that can endorse cells with the landmarks required to maintain transcriptional programs upon cell duplication. Here, we review current literature analyzing the molecular basis of epigenetic memory in mammals, with a focus on the mechanisms by which transcriptionally repressive chromatin modifications such as methylation of DNA and histone H3 are propagated through mitotic cell divisions. The emerging picture suggests that cellular memory is supported by an epigenetic cycle in which reversible activities carried out by epigenetic regulators in coordination with cell cycle transition create a multiphasic system that can accommodate both maintenance of cell identity and cell differentiation in proliferating stem cell populations.

Femtoliter oil droplets act as CO2 micropumps for uninterrupted electrochemiluminescence at the water|oil interface

Interfacial effects are well-known to significantly alter chemical reactivity, especially in confined environments, where the surface to volume ratio increases. Here, we observed an inhomogeneity in the electrogenerated chemiluminescence (ECL) intensity decrease over time in a multiphasic system composed of femtoliter water droplets entrapping femtoliter volumes of the 1,2-dichloroethane (DCE) continuous phase. In usual electrochemiluminescence (ECL) reactions involving an ECL chromophore and oxalate ([C2O4]2−), the build-up of CO2 diminishes the ECL signal with time because of bubble formation. We hypothesised that relative solubilities of chemical species in these environments play a dramatic role in interfacial reactivity. Water droplets, loaded with the ECL luminophore [Ru(bpy)3]2+ and the coreactant [C2O4]2− were allowed to stochastically collide and adsorb at the surface of a glassy carbon macroelectrode. When water droplets coalesce on the surface, they leave behind femtoliter droplets of the DCE phase (inclusions). We report the surprising finding that the addition of multiple interfaces, due to the presence of continuous phase’s femtoliter inclusions, allows sustained ECL over time after successive potential applications at the triple-phase boundary between water droplet|electrode|DCE inclusion. When femtoliter droplets of DCE form on the electrode surface, bright rings of ECL are observed during the simultaneous oxidation of [Ru(bpy)3]2+ and [C2O4]2−. Control experiments and finite element modelling allowed us to propose that these rings arise because CO2 that is generated near the 1,2-dichloroethane droplet partitions in due to relative solubility of CO2 in 1,2-dichloroethane and builds up and/or is expelled at the top of the droplet. The small droplets of the DCE phase act as micropumps, pumping away carbon dioxide from the interface. These results highlight the unexpected point that confined microenvironments and their geometry can tune chemical reactions of industrial importance and fundamental interest.

Bismuth and Cobalt Multiphasic System: Synthesis and Application as Microstrip Patch Antenna Substrate

Bismuth and Cobalt Multiphasic System: Synthesis and Application as Microstrip Patch Antenna Substrate

Harnessing Biofabrication Strategies to Re-Surface Osteochondral Defects: Repair, Enhance, and Regenerate.

Osteochondral tissue (OC) is a complex and multiphasic system comprising cartilage and subchondral bone. The discrete OC architecture is layered with specific zones characterized by different compositions, morphology, collagen orientation, and chondrocyte phenotypes. To date, the treatment of osteochondral defects (OCD) remains a major clinical challenge due to the low self-regenerative capacity of damaged skeletal tissue, as well as the critical lack of functional tissue substitutes. Current clinical approaches fail to fully regenerate damaged OC recapitulating the zonal structure while granting long-term stability. Thus, the development of new biomimetic treatment strategies for the functional repair of OCDs is urgently needed. Here, we review recent developments in the preclinical investigation of novel functional approaches for the resurfacing of skeletal defects. The most recent studies on preclinical augmentation of OCDs and highlights on novel studies for the in vivo replacement of diseased cartilage are presented.

Thermo-switchable hydrophobic solvents formulated with weak acid and base for greener separation processes

Switchable solvents are changing properties when exposed to an external stimulus. As example, for thermomorphic multiphasic system (TMS), temperature changes can induce phase separations. Aqueous systems presented here are formulated with a carboxylic acid (weak acid) and an amphiphilic tertiary amine (weak base). They show thermo-switchable hydrophobicity and after separation, the weak acid and base are mainly found in the organic phase while the aqueous phase is mostly composed of water, up to 99 wt%. The phase separation temperature (cloud point) can be tuned from 20 to 80 °C depending on the choice of the carboxylic acid and on the acid: base molar ratio. A collection of saturated aliphatic carboxylic acids and benzoic acid derivatives have been investigated to evaluate the impact of different physico-chemical properties on the cloud point. The octanol/water partition coefficient (log P) and acidic constant (pKa) were identified as key physico-chemical properties to adjust the phase separation temperature. Finally, as illustration of the efficiency of these systems to remove a chemical from water, it has been shown that 99 % extraction of an anionic dye, methyl orange, could be achieved with most of the tested TMS.

One-step fabrication of multiphasic Janus microparticles with programmed degradation properties based on a microfluidic chip

This work aimed to develop a multiphasic Janus particle system for programmed drug delivery. A phase separation based one-step microfluidic preparation process was demonstrated to generate triple-phase Janus microparticles with different degradation properties in each phase. In this system, particles with a series of complicated structures were generated, and programmed degradation behaviors according to the structures were achieved. Partial degradation of the particles and cargo release triggered by change of ambient temperature or pH could be realized as well. Further, graphene nanosheets and silica nanospheres were modified in the microparticles by using the principle of Pickering emulsion to enrich the functions of the particles. To reveal the potential of the particles in drug delivery applications, doxorubicin and curcumin were co-loaded in triple-phase microparticles, and zonal drug loading was achieved. In vitro drug release profiles and tumor cell apoptosis study indicated that the particles provided programmed release behavior as well as enhanced tumor inhibition efficacy compared with free drug administration and monophasic particles. This study proposed a facile and one-step fabrication method of multiphasic particles possessing programmed and triggered drug release kinetics, and may be the first attempt to generate triple-phase particles with phase separation method in a droplet microfluidic chip.

A Self-Separating Multiphasic System for Catalytic Hydrogenation of CO2 and CO2 -Derivatives to Methanol.

Catalytic conversion of CO2 and hydrogen to methanol was achieved in a self-separating multiphasic system comprising the tailor-made complex [Ru(CO)ClH(MACHO-C12 )] (MACHO-C12 =bis{2-[bis(4-dodecylphenyl)phosphino]ethyl}amine) in n-decane as the catalyst phase. Effective catalyst recycling was demonstrated for the carbonate and the amine-assisted pathway from CO2 to methanol. The polar products MeOH or MeOH/H2 O generated from the catalytic reactions spontaneously formed a separate phase, allowing product isolation and catalyst separation without the need for any additional solvent. In the amine-assisted hydrogenation of CO2 , the catalyst phase was recycled over ten subsequent runs, reaching a total turnover number to MeOH of 19200 with an average selectivity of 96 %.

A Deep Eutectic Solvent Thermomorphic Multiphasic System for Biocatalytic Applications.

The applicability of a thermomorphic multiphasic system (TMS) composed of a hydrophobic deep eutectic solvent (DES) and an aqueous potassium phosphate buffer with a lower critical solution temperature (LCST) phase change for homogeneous biocatalysis was investigated. A lidocaine‐based DES with the fatty acid oleic acid as a hydrogen‐bond donor was studied. Phase diagrams were determined and presented within this study. We tested different additional components to the solvent system and observed a decrease in the cloud point of approximately 0.026 °C per concentration unit. Distribution studies revealed a clear distribution of the protein in the aqueous buffer phase (>95 %), whereas the hydrophobic substrate and educt accumulated (>95 %) in the DES‐enriched layer. Finally, a reduction catalyzed by horse liver alcohol dehydrogenase was performed in a larger‐scale experiment, and the biocatalyst could be recycled by simply removing the DES phase for three recycling runs.

Microfluidics: A Novel Approach for Dehydration Protein Droplets.

The equation of state of colloids plays an important role in the modelling and comprehension of industrial processes, defining the working conditions of processes such as drying, filtration, and mixing. The determination of the equation is based on the solvent equilibration, by dialysis, between the colloidal suspension and a reservoir with a known osmotic pressure. In this paper, we propose a novel microfluidic approach to determine the equation of state of a lysozyme solution. Monodispersed droplets of lysozyme were generated in the bulk of a continuous 1-decanol phase using a flow-focusing microfluidic geometry. In this multiphasic system and in the working operation conditions, the droplets can be considered to act as a permeable membrane system. A water mass transfer flow occurs by molecule continuous diffusion in the surrounding 1-decanol phase until a thermodynamic equilibrium is reached in a few seconds to minutes, in contrast with the standard osmotic pressure measurements. By changing the water saturation of the continuous phase, the equation of state of lysozyme in solution was determined through the relation of the osmotic pressure between protein molecules and the volume fraction of protein inside the droplets. The obtained equation shows good agreement with other standard approaches reported in the literature.

Numerical-modeling-based investigation of sound transmission and reception in the short-finned pilot whale (Globicephala macrorhynchus)

The sound-transmission, beam-formation, and sound-reception processes of a short-finned pilot whale (Globicephala macrorhynchus) were investigated using computed tomography (CT) scanning and numerical simulation. The results showed that sound propagations in the forehead were modulated by the upper jaw, air components, and soft tissues, which attributed to the beam formation in the external acoustic field. These structures owned different acoustic impedance and formed a multiphasic sound transmission system that can modulate sounds into a beam. The reception pathways composed of the solid mandible and acoustic fats in the lower head conducted sounds into the tympano-periotic complex. In the simulations, sounds were emitted in the forehead transmission system and propagated into water to interrogate a steel cylinder. The resulting echoes can be interpreted from multiple perspectives, including amplitude, waveform, and spectrum, to obtain the acoustic cues of the steel cylinder. By taking the short-finned pilot whale as an example, this study provides meaningful information to further deepen our understanding of biosonar system operations, and may expand sound-reception theory in odontocetes.

Concurrent multi-lineage differentiation of mesenchymal stem cells through spatial presentation of growth factors

Severe tendon and ligament injuries are estimated to affect between 300 000 and 400 000 people annually. Surgical repairs of these injuries often have poor long-term clinical outcomes because of resection of the interfacial tissue—the enthesis—and subsequent stress concentration at the attachment site. A healthy enthesis consists of distinct regions of bone, fibrocartilage, and tendon, each with distinct cell types, extracellular matrix components, and architecture, which are important for tissue function. Tissue engineering, which has been proposed as a potential strategy for replacing this tissue, is currently limited by its inability to differentiate multiple lineages of cells from a single stem cell population within a single engineered construct. In this study, we develop a multi-phasic gelatin methacrylate hydrogel construct system for spatial presentation of proteins, which is then validated for multi-lineage differentiation towards the cell types of the bone-tendon enthesis. This study determines growth factor concentrations for differentiation of mesenchymal stem cells towards osteoblasts, chondrocytes/fibrochondrocytes, and tenocytes, which maintain similar differentiation profiles in 3D hydrogel culture as assessed by qPCR and immunofluorescence staining. Finally, it is shown that this method is able to guide heterogeneous and spatially confined changes in mesenchymal stem cell genes and protein expressions with the tendency to result in osteoblast-, fibrochondrocyte-, and tenocyte-like expression profiles. Overall, we demonstrate the utility of the culture technique for engineering other musculoskeletal tissue interfaces and provide a biochemical approach for recapitulating the bone-tendon enthesis in vitro.

Effect of processing temperature and mixing time on the properties of PP/GnP nanocomposites

During processing of molten polymers the thermal and mechanical stress acting on the melt in presence of oxygen can induce degradation with a modification of the chemical structure of the polymers. This picture can become even more relevant if the melt is a multiphasic polymer system. In this last case, the effects of the degradation depend also on the presence of a second phase and on the interactions between the two phases.In this work, the effect of the processing conditions, temperature and time, have been considered in order to investigate the thermo-mechanical and thermo-oxidative degradation of nanocomposites made by polypropylene and different contents of graphene nanoplatelets. Graphene nanoplatelets improve the stability of the polymer matrix and the sample with the lower content of nanofiller shows a lower level of degradation. The better resistance of the filled samples has been interpreted with a barrier effect to the oxygen of the nanofiller that hinders the transport of oxygen necessary for the oxidation of the polypropylene. The unexpected effect of the concentration of graphene nanoplatelets has been correlated with the agglomeration of the nanoplatelets that reduces the surface area of the filler and then the barrier effect to the oxygen.

A novel Borrelia species, intermediate between Lyme disease and relapsing fever groups, in neotropical passerine-associated ticks

Lyme disease (LD) and relapsing fevers (RF) are vector-borne diseases caused by bacteria of the Borrelia genus. Here, we report on the widespread infection by a non-described Borrelia species in passerine-associated ticks in tropical rainforests of French Guiana, South America. This novel Borrelia species is common in two tick species, Amblyomma longirostre and A. geayi, which feed on a broad variety of neotropical mammal and bird species, including migratory species moving to North America. The novel Borrelia species is divergent from the LD and RF species, and is more closely related to the reptile- and echidna-associated Borrelia group that was recently described. Genome sequencing showed that this novel Borrelia sp. has a relatively small genome consisting of a 0.9-Mb-large chromosome and an additional 0.3 Mb dispersed on plasmids. It harbors an RF-like genomic organization but with a unique mixture of LD- and RF-specific genes, including genes used by RF Borrelia for the multiphasic antigen-switching system and a number of immune-reactive protein genes used for the diagnosis of LD. Overall, our data indicate that this novel Borrelia is an intermediate taxon between the LD and RF species that may impact a large host spectrum, including American mammals. The designation “Candidatus Borrelia mahuryensis” is proposed for this species.

Biphasic Hydrogels Integrating Mineralized and Anisotropic Features for Interfacial Tissue Engineering.

The innate graded structural and compositional profile of musculoskeletal tissue interfaces is disrupted and replaced by fibrotic tissue in the context of disease and degeneration. Tissue engineering strategies focused on the restoration of the transitional complexity found in those junctions present special relevance for regenerative medicine. Herein, we developed a gelatin-based multiphasic hydrogel system, where sections with distinct composition and microstructure were integrated in a single unit. In each phase, hydroxyapatite particles or cellulose nanocrystals (CNC) were incorporated into an enzymatically cross-linked gelatin network to mimic bone or tendon tissue, respectively. Stiffer hydrogels were produced with the incorporation of mineralized particles, and magnetic alignment of CNC resulted in anisotropic structure formation. The evaluation of the biological commitment with human adipose-derived stem cells toward the tendon-to-bone interface revealed an aligned cell growth and higher synthesis and deposition of tenascin in the anisotropic phase, while the activity of the secreted alkaline phosphatase and the expression of osteopontin were induced in the mineralized phase. These results highlight the potential versatility offered by gelatin-transglutaminase enzyme tandem for the development of strategies that mimic the graded, composite, and complex intersections of the connective tissues.

Hybrid Rubberised Bitumen from Reactive and Non-Reactive Ethylene Copolymers.

Hybrid modification is a relatively new concept of incorporating two or more polymeric modifiers of different nature to a bitumen, in order to take advantage of their complementary features. Aiming to this, in this paper, the so-called Hybrid Systems (HSs) were prepared by the addition of an ethylene-based copolymer (reactive or non-reactive) to a model rubberised binder (Crumb Tyre Rubber Modified Bitumen). The resulting binders (referred to as reactive and non-reactivate HSs, depending on copolymer used) were evaluated by means of thermorheological analysis, technological characterisation, fluorescence microscopy and modulated differential scanning calorimetry. From the experimental results, it may be deduced a positive synergistic effect of non-dissolved Crumb Tyre Rubber (CTR) particles and a second polymeric phase that not only improves the in-service performance but also the high-temperature storage stability. This enhancement is attributed to the development of a multiphasic system composed of non-dissolved CTR particles, a polymer-rich phase and an asphaltene-rich phase. In the case of non-reactive HSs, droplets of swollen ethylene copolymer form a well-defined dispersed phase. By contrast, reactive HSs display a different morphology, almost invisible by optical microscopy, related to the development of a chemical network that yields, by far, the highest degree of modification.

Influence of Protonic Ionic Liquid on the Dispersion of Carbon Nanotube in PLA/EVA Blends and Blend Compatibilization

In this work, immiscible poly(lactic acid) (PLA)/poly(ethylene vinyl acetate) (EVA) composites with 1 phr of multi‐walled carbon nanotube (CNT) and different concentration of protonic – based imidazolium ionic liquid (mimbSO3H.Cl) were prepared. The protonic ionic liquid (IL) was able to act as dispersing agent for CNT and as compatibilizing agent for the PLA/EVA blend. The multicomponent nanocomposites from the mixture of PLA and EVA containing CNT functionalized with ionic liquid, IL (CNT/ILSO3H) were characterized by mechanical and dynamic - mechanical (DMA) tests, electrical conductivity analyses, differential scanning calorimetry (DSC), X-ray diffraction analysis and rheological measurements, as well as chromatographic gel permeation (GPC), and scanning electron microscopy (SEM). The non covalent functionalization CNT resulted in composites with outstanding electrical and dielectric properties. The high dispersion of CNT promoted by the IL resulted in the formation of a physical networked structure, which was responsible for the higher electrical conductivity and higher melt viscosity. The crystallization process of PLA phase was improved with the presence of CNT/ILSO3H. The degradation process during the transesterification reaction did not significantly affect the mechanical properties. The present work highlights the dual role of the IL as compatibilizing and dispersing agent and opens new perspectives for developing new conducting systems with low percolation threshold based on the good dispersion of CNT and the confinement of the filler within a phase of a multiphasic polymeric system.

Genome-wide analysis of Borrelia turcica and ‘Candidatus Borrelia tachyglossi’ shows relapsing fever-like genomes with unique genomic links to Lyme disease Borrelia

Borrelia are tick-borne bacteria that in humans are the aetiological agents of Lyme disease and relapsing fever. Here we present the first genomes of B. turcica and B. tachyglossi, members of a recently described and rapidly expanding Borrelia clade associated with reptile (B. turcica) or echidna (B. tachyglossi) hosts, transmitted by hard ticks, and of unknown pathogenicity. Borrelia tachyglossi and B. turcica genomes are similar to those of relapsing fever Borrelia species, containing a linear ~ 900 kb chromosome, a single long (> 70 kb) linear plasmid, and numerous short (< 40 kb) linear and circular plasmids, as well as a suite of housekeeping and macronutrient biosynthesis genes which are not found in Lyme disease Borrelia. Additionally, both B. tachyglossi and B. turcica contain paralogous vsp and vlp proteins homologous to those used in the multiphasic antigen-switching system used by relapsing fever Borrelia to evade vertebrate immune responses, although their number was greatly reduced compared to human-infectious species. However, B. tachyglossi and B. turcica chromosomes also contain numerous genes orthologous to Lyme disease Borrelia-specific genes, demonstrating a unique evolutionary, and potentially phenotypic link between these groups. Borrelia tachyglossi and B. turcica genomes also have unique genetic features, including degraded and deleted tRNA modification genes, and an expanded range of macronutrient salvage and biosynthesis genes compared to relapsing fever and Lyme disease Borrelia. These genomes and genomic comparisons provide an insight into the biology and evolutionary origin of these Borrelia, and provide a valuable resource for future work.

Recent developments in biocatalysis in multiphasic ionic liquid reaction systems.

Ionic liquids are well known and frequently used 'designer solvents' for biocatalytic reactions. This review highlights recent achievements in the field of multiphasic ionic liquid-based reaction concepts. It covers classical biphasic systems including supported ionic liquid phases, thermo-regulated multi-component solvent systems (TMS) and polymerized ionic liquids. These powerful concepts combine unique reaction conditions with a high potential for future applications on a laboratory and industrial scale. The presence of a multiphasic system simplifies downstream processing due to the distribution of the catalyst and reactants in different phases.

Determinants on an efficient cellulase recycling process for the production of bioethanol from recycled paper sludge under high solid loadings

BackgroundIn spite of the continuous efforts and investments in the last decades, lignocellulosic ethanol is still not economically competitive with fossil fuels. Optimization is still required in different parts of the process. Namely, the cost effective usage of enzymes has been pursued by different strategies, one of them being recycling.ResultsCellulase recycling was analyzed on recycled paper sludge (RPS) conversion into bioethanol under intensified conditions. Different cocktails were studied regarding thermostability, hydrolysis efficiency, distribution in the multiphasic system and recovery from solid. Celluclast showed inferior stability at higher temperatures (45–55 °C), nevertheless its performance at moderate temperatures (40 °C) was slightly superior to other cocktails (ACCELLERASE®1500 and Cellic®CTec2). Celluclast distribution in the solid–liquid medium was also more favorable, enabling to recover 88% of final activity at the end of the process. A central composite design studied the influence of solid concentration and enzyme dosage on RPS conversion by Celluclast. Solids concentration showed a significant positive effect on glucose production, no major limitations being found from utilizing high amounts of solids under the studied conditions. Increasing enzyme loading from 20 to 30 FPU/gcellulose had no significant effect on sugars production, suggesting that 22% solids and 20 FPU/gcellulose are the best operational conditions towards an intensified process. Applying these, a system of multiple rounds of hydrolysis with enzyme recycling was implemented, allowing to maintain the steady levels of enzyme activity with only 50% of enzyme on each recycling stage. Additionally, interesting levels of solid conversion (70–81%) were also achieved, leading to considerable improvements on glucose and ethanol production comparatively with the reports available so far (3.4- and 3.8-fold, respectively).ConclusionsEnzyme recycling viability depends on enzyme distribution between the solid and liquid phases at the end of hydrolysis, as well as enzymes thermostability. Both are critical features to be observed for a judicious choice of enzyme cocktail. This work demonstrates that enzyme recycling in intensified biomass degradation can be achieved through simple means. The process is possibly much more effective at larger scale, hence novel enzyme formulations favoring this possibility should be developed for industrial usage.

Effect of Biomass Concentration on Oxygen Mass Transfer, Power Consumption, Interfacial Tension and Hydrodynamics in a Multiphase Partitioning Bioreactor

Abstract Several studies have reported that the hydrodynamics are not affected by the biomass in multiphase partitioning bioreactors. This work aims to demonstrate the effect of biomass concentration (0, 1, 3 and 5 g L−1) on the oxygen mass transfer coefficients, the droplet size of the dispersed phase, power consumption and superficial tension in a multiphase partitioning bioreactor (ionic liquid-aqueous-air-biomass system). At a biomass concentration of 5 g L−1, the oxygen mass transfer coefficient (kLa) increased by 55% (249 h−1) compared with the abiotic system (160 h−1). In the multiphasic system, the droplet size (d32) decreased when the biomass concentration was increased, producing an increment in the mass transfer area of the dispersed phase. In addition, the power consumption decreased by 44 % compared to a previous report without biomass. Furthermore, the increment of biomass concentration decreased the superficial tension by up to 15 %. A biomass increment in a multiphase system not also increases product yield, but also enhances the bioconversion process. The results obtained suggest that it is obligatory to consider the effect of biomass concentration on hydrodynamic characterisation, design, scale-up and optimisation for improving the performance of biotechnological processes using multiphase bioreactors.