Charged Ones Research Articles

Facile generation of giant unilamellar vesicles using polyacrylamide gels

Giant unilamellar vesicles (GUVs) are model cell-sized systems that have broad applications including drug delivery, analysis of membrane biophysics, and synthetic reconstitution of cellular machineries. Although numerous methods for the generation of free-floating GUVs have been established over the past few decades, only a fraction have successfully produced uniform vesicle populations both from charged lipids and in buffers of physiological ionic strength. In the method described here, we generate large numbers of free-floating GUVs through the rehydration of lipid films deposited on soft polyacrylamide (PAA) gels. We show that this technique produces high GUV concentrations for a range of lipid types, including charged ones, independently of the ionic strength of the buffer used. We demonstrate that the gentle hydration of PAA gels results in predominantly unilamellar vesicles, which is in contrast to comparable methods analyzed in this work. Unilamellarity is a defining feature of GUVs and the generation of uniform populations is key for many downstream applications. The PAA method is widely applicable and can be easily implemented with commonly utilized laboratory reagents, making it an appealing platform for the study of membrane biophysics.

Energy and exergy analysis of wind farm integrated with compressed air energy storage using multi-stage phase change material

One of the most common issues associated with wind energy penetration as a viable resource is high instability under diverse amplitudes and frequencies. Compressed air storage systems (CAES) and thermal energy storages (TES) not only are promising alternative solution for renewable resources generally, but they are also used with the aim of peak shaving to provide cleaner and affordable power. Due to high storage density with low temperature gradient between storing and retrieving in comparison with sensible heat storage, phase change material (PCM) is selected considering their thermophysical properties. This work, presents a recovery approach by using PCM during 12 h’ compression periods to retrieve it in 12 h’ expansion as a case study in November for Baladeh (a city in north of Iran). It is worthy to mention that, in order to use PCM in multiple mentioned stages, auxiliary heaters facilitate system to provide constant heat load in each used stage. This concludes system to be more efficient, sustainable and can reduce irreversibilities. Temperature of PCMs and amount of heat stored and released versus time are modeled. A good agreement between PCM model and reported results of related articles was seen. Following to the energy and exergy balances calculation, round-trip efficiency (RTE) and total exergy efficiency of system, reach 70.83%, 80.71%. Exergy analysis showed that near 60% exergy destruction occurred in PCMs with major contribution of second ones in both charge and discharge times. Sensitivity analysis is also investigated assuming the effect of number of wind turbines which shows a reduction in RTE, steeper slope in increasing TES volume for PCM3 and amount of heat stored, by increasing them.

Molecular Insights into Distinct Detection Properties of α-Hemolysin, MspA, CsgG, and Aerolysin Nanopore Sensors.

Protein nanopores have been widely used as single-molecule sensors for the detection and characterization of biological polymers such as DNA, RNA, and polypeptides. A variety of protein nanopores with various geometries have been exploited for this purpose, which usually exhibit distinct sensing capabilities, but the underlying molecular mechanism remains elusive. Here, we systematically characterize the molecular transport properties of four widely studied protein nanopores, α-hemolysin, MspA, CsgG, and aerolysin, by extensive molecular dynamics simulations. It is found that a sudden drop in electrostatic potentials occurs at the sole constriction in MspA and CsgG nanopores in contrast to the gradual potential change inside α-hemolysin and aerolysin pores, indicating the crucial role of pore geometry in ionic and molecular transport. We further demonstrate that these protein nanopores exhibit open-pore currents and ssDNA-induced current blockades both in the order MspA > α-hemolysin > CsgG > aerolysin, but an equivalent blockade percentage around 80%. In addition, the substitution of key amino acids at the pore constriction, especially by charged ones, provides an efficient way to modulate the pore electrostatic potential and ionic current. This work sheds new light on the search for high-performance nanopores, engineering of protein nanopores, and design of bioinspired solid-state nanopores.

Influence of the viscosity and charge mobility on the shape deformation of critically charged droplets

In this work, we model and simulate the shape evolution of critically charged droplets, from the initial spherical shape to the charge emission and back to the spherical shape. The shape deformation is described using the viscous correction for viscous potential flow model, which is a potential flow approximation of the Navier-Stokes equation for incompressible Newtonian fluids. The simulated shapes are compared to snapshots of experimentally observed drop deformations. We highlight the influence of the dimensionless viscosity and charge carrier mobility of the liquid on the shape evolution of droplets and discuss the observed trends. We give an explanation as to why the observed deformation pathways of positively and negatively charged pure water droplets differ and give a hint as to why negatively charged water droplets emit more charge during charge breakup than positively charged ones.

Poéticas de la oposición: Política y obra cultural en la España actual by Jonathan Snyder

Reviewed by: Poéticas de la oposición: Política y obra cultural en la España actual by Jonathan Snyder Douglas LaPrade Snyder, Jonathan. Poéticas de la oposición: Política y obra cultural en la España actual. Brumaria, 2018. Pp. 380. ISBN 978-8-49492-470-5. This translation into Spanish of Jonathan Snyder’s book analyzes artistic responses to Spain’s 15-M Movement, the social revolution named for the mass demonstrations in Madrid’s Puerta del Sol on May 15, 2011. Snyder establishes a context for the 15-M Movement with references to the May 1968 protests in Paris, to the Arab Spring of 2010, and to Iceland’s financial crisis after 2008. Snyder also cites Stéphane Hessel’s book entitled Indignez-vous! The title of this book, published in 2010, leant its name to Spain’s protestors, the Indignados. The 15-M Movement was the Spanish public’s response to the global economic crisis of 2008, when the American subprime mortgage market collapsed. Spain’s economy suffered greatly after 2008, and unemployment rates worsened. Poéticas de la oposición: Política y obra cultural en la España actual’s success is a result of the author’s astute selection process in choosing works of art that illustrate the 15-M Movement. In his preface, Snyder discusses an unconventional performance/exhibit by Fran Mohíno at the Matadero, Madrid’s former slaughterhouse, which was converted into a cultural center in 2007 to feature experimental art not found in traditional museums. As the Indignados protest Spain’s political, social, and economic institutions, Spanish artists produce works suggesting how they have been disenfranchised by traditional cultural institutions. The book’s first chapter analyzes poetry by Gregorio Apesteguía that has appeared in literary fanzines rather than in conventional publications. Like the Matadero, the fanzine is [End Page 131] for art produced outside the mainstream. Snyder chooses to analyze poems by Apesteguía that allude to Spain’s proud poetic heritage, thus lamenting its demise. For example, Apesteguía has published a series of poems entitled “Coplas a la muerte de Europa,” a clear allusion to Jorge Manrique’s fifteenth-century classic, Coplas por la muerte de su padre. The title of Apesteguía’s poem parodies Spain’s traditions and suggests that the European Union has failed to help Spain adjust to the modern era. Another poem by Apesteguía quotes a famous poem by San Juan de la Cruz—“En una noche oscura”—but drowns out the mystic poet’s meditations with the sound of a passing commuter train. The second chapter features an example of performance art that defies categorization according to genre or medium. On August 15, 2012, Santiago Sierra and Jorge Galindo filmed a simulated motorcade on Madrid’s Gran Vía. The performance was called Los encargados (The Ones in Charge). The procession consisted of seven apparently official cars, each of which transported on its roof an upside-down portrait of one of Spain’s leaders since the Transition. The first car bore the image of King Juan Carlos I, and the subsequent cars transported the portraits of the presidents from Adolfo Suárez to Mariano Rajoy. The event was a parody designed to ridicule the solemnity and dignity of official motorcades. The organizers Sierra and Galindo thereby staged an event designed to reclaim or appropriate the Gran Vía from the official leaders. The third chapter discusses a photography exhibit entitled El último verano (Last Summer) by members of Nophoto, a collective of artists whose work documents the summer of 2012. One of the most representative photographs, by Paco Gómez, features a woman lying on the railroad in a small town in Extremadura. Because of economic hardship, the train will no longer pass through this town, which is on the track connecting Madrid and Lisbon. Without the train, the small town’s economy will suffer even further. The woman lying on the railroad in the photograph is not in danger of being run over by the cancelled train, but the town’s economy will surely die. The fourth chapter discusses plays by Abril Zamora, notably Temporada...

Particle emission from two-dimensional MoS2 induced by highly charged ion impact

SynopsisFor many attractive applications of single layer MoS2 such as in optoelectronics e.g., the sample is supported by a substrate. Its importance for the modification through ion irradiation is here experimentally investigated by the analysis of sputtered particle of MoS2 on SiO2 and Au substrates under highly charged ion irradiation. The velocity distribution of the sputtered atoms is less affected by the substrate using highly charged projectiles than using slightly charged ones. Furthermore, we can show that potential sputtering causes additional emission of particles with lower kinetic energy.

Particle nucleation and growth in dusty plasmas: On the importance of charged-neutral interactions

Particle nucleation and growth in gases involves nucleation via growth of small molecular or ionic clusters, growth by vapor deposition on nanoparticle surfaces, and coagulation due to collisions between nanoparticles. Under typical conditions that apply in low-pressure nonthermal plasmas, all three of these phenomena are dominated by interactions between negatively charged bodies (anion clusters or nanoparticles) and neutral ones (molecules or nanoparticles), with collision rates enhanced by the dipole or image potential induced in the neutral collision partner. The current understanding of these phenomena is reviewed, with a focus on silane-containing plasmas in which silicon nanoparticles nucleate and grow.

A Quantum Electromagnetic Theory of the Pions, Muons and Their Emitting Particles (I)

In direct accordance to the overall relevant experimental demonstrations, we represent the charged pion π- as a heavy electron h- in precessional-orbital (P-O) motion at essentially the light speed c about -orbit of a normal at quantised angle π − θ1/2 = − arccos to the z axis. h- is the level N = 1 oscillation of charge −e and its electromagnetic radiation originally generated in the weak potential field of another particle. The P-O kinetic energy current and two additional opposite ones created upon π- decay represent confined neutrinos . The muon µ- is a xy-projected h- in two superposing P-O motions along - orbits of normals at angles π − θ1/2, θ1/2 to z. The µ- (rest) mass is a geometric projection of the reduced π- mass, . The µ- mass is fundamentally predetermined by the mixed two states ml = −1, +1 of level n = 2 of a double heavy positronium in the CM frame produced in a relativistic e-, e+ collision, and is ab initio predicted to be , where . The un-projected n = 2 level gives the bound π- mass containing a friction term . Their antiparticles π+, µ+ and the tauons τ∓ can be similarly represented. The remaining unstable elementary particles can be constructed as composites of two or more single charged ones in certain spatial quantised P-O motions.

Design of a New [PSI +]-No-More Mutation in SUP35 With Strong Inhibitory Effect on the [PSI +] Prion Propagation.

A number of [PSI+]-no-more (PNM) mutations, eliminating [PSI+] prion, were previously described in SUP35. In this study, we designed and analyzed a new PNM mutation based on the parallel in-register β-structure of Sup35 prion fibrils suggested by the known experimental data. In such an arrangement, substitution of non-charged residues by charged ones may destabilize the fibril structure. We introduced Q33K/A34K amino acid substitutions into the Sup35 protein, corresponding allele was called sup35-M0. The mutagenized residues were chosen based on ArchCandy in silico prediction of high inhibitory effect on the amyloidogenic potential of Sup35. The experiments confirmed that Sup35-M0 leads to the elimination of [PSI+] with high efficiency. Our data suggested that the elimination of the [PSI+] prion is associated with the decreased aggregation properties of the protein. The new mutation can induce the prion with very low efficiency and is able to propagate only weak [PSI+] prion variants. We also showed that Sup35-M0 protein co-aggregates with the wild-type Sup35 in vivo. Moreover, our data confirmed the utility of the strategy of substitution of non-charged residues by charged ones to design new mutations to inhibit a prion formation.

Neto proteins regulate gating of the kainate-type glutamate receptor GluK2 through two binding sites

The neuropilin and tolloid-like (Neto) proteins Neto1 and Neto2 are auxiliary subunits of kainate-type glutamate receptors (KARs) that regulate KAR trafficking and gating. However, how Netos bind and regulate the biophysical functions of KARs remains unclear. Here, we found that the N-terminal domain (NTD) of glutamate receptor ionotropic kainate 2 (GluK2) binds the first complement C1r/C1s-Uegf-BMP (CUB) domain of Neto proteins (i.e. NTD-CUB1 interaction) and that the core of GluK2 (GluK2ΔNTD) binds Netos through domains other than CUB1s (core-Neto interaction). Using electrophysiological analysis in HEK293T cells, we examined the effects of these interactions on GluK2 gating, including deactivation, desensitization, and recovery from desensitization. We found that NTD deletion does not affect GluK2 fast gating kinetics, the desensitization, and the deactivation. We also observed that Neto1 and Neto2 differentially regulate GluK2 fast gating kinetics, which largely rely on the NTD-CUB1 interactions. NTD removal facilitated GluK2 recovery from desensitization, indicating that the NTD stabilizes the GluK2 desensitization state. Co-expression with Neto1 or Neto2 also accelerated GluK2 recovery from desensitization, which fully relied on the NTD-CUB1 interactions. Moreover, we demonstrate that the NTD-CUB1 interaction involves electric attraction between positively charged residues in the GluK2_NTD and negatively charged ones in the CUB1 domains. Neutralization of these charges eliminated the regulatory effects of the NTD-CUB1 interaction on GluK2 gating. We conclude that KARs bind Netos through at least two sites and that the NTD-CUB1 interaction critically regulates Neto-mediated GluK2 gating.

Investigation of Dusty Plasma Based on the Ornstein—Zernike Integral Equation for a Multicomponent Fluid

The electrostatic interaction between charged particles in a dusty plasma has been studied using the Ornstein—Zernike integral equation for a multicomponent plasma. The transition to the one-component approximation has been performed for the nonideal plasma subsystem. It has been shown that the interaction between charged plasma particles at the coupling parameter Γ of the dust subsystem less than unity is well described by the Debye potential with the complete screening constant. The static dielectric function in the region of low wavenumbers becomes negative at Γ > 1 and this region expands with increasing Γ. As a result, attraction between likely charged particles and repulsion between oppositely charged ones occur in a certain distance range. In this case, the total pressure, specific heat at constant volume, and isothermal compressibility of the dusty plasma remain positive in the entire studied range of the nonideality parameter Γ < 250, but the isothermal compressibility of only the dust nonideal subsystem becomes negative at Γ ≈ 2.

Protein Translational Diffusion and Intermolecular Interactions of Globular and Intrinsically Unstructured Proteins.

The study of intermolecular interactions of proteins has been an important problem for many years. This paper presents an approach to analyze different levels of protein interactions in solutions through a set of the second- and higher-order virial coefficients. The proposed approach is based on the diversified analysis of protein translational collective diffusion and self-diffusion obtained by dynamic light scattering and the pulsed-field gradient NMR (PFG NMR) spectroscopy experimental data. The experimental results were analyzed within the theoretical approach based on Vink's frictional formalism of nonequilibrium thermodynamics and the standard Derjaguin-Landau-Verwey-Overbeekb (DLVO) theory of interactions of colloid particles in electrolyte solutions. The second- and higher-order virial coefficients were obtained to estimate the pairwise and many-body intermolecular interactions in the solutions of globular α-chymotrypsin and intrinsically unstructured αS-casein. The second virial coefficients were calculated from the model of the protein-protein potential of mean force. The description of protein-protein interactions includes a set of interaction potentials: the attractive charge-dipole, dipole-dipole, the dispersion Hamaker, the mean force osmotic-attraction, and the repulsive charge-charge ones. It has been found that the major contribution to the intermolecular αS-casein interactions is made by the repulsive charge-charge potential, whereas for the case of α-chymotrypsin, the contributions from other types of interaction are of importance. It was determined that the model was well suited to describe the interactions of both globular and intrinsically disordered proteins. The suggested combination of Vink's approach and the DLVO theory is novel and holds much promise to make a profound analysis of the processes in systems containing various types of protein molecules.

Charged particle production rate from cosmic censorship in dilaton black hole spacetimes

Hiscock and Weems showed that under Hawking evaporation, an isolated asymptotically flat Reissner-Nordström (RN) black hole evolves in a surprising manner: if it starts with a relatively small value of charge-to-mass ratio Q/M, then said value will temporarily increase along its evolutionary path, before finally decreases towards zero. This contrasts with highly charged ones that simply radiate away its charge steadily. The combination of these two effects is the cosmic censor at work: there exists an attractor that flows towards the Schwazschild limit, which ensures that extremality — and hence naked singularity — can never be reached under Hawking evaporation. We apply the scheme of Hiscock and Weems to model the evaporation of an asymptotically flat dilatonic charge black hole known as the Garfinkle-Horowitz-Strominger (GHS) black hole. We found that upholding the cosmic censorship requires us to modify the charged particle production rate, which remarkably agrees with the expression obtained independently via direct computation of charged particle production rate on curved spacetime background. This not only strengthens the case for cosmic censorship, but also provides an example in which cosmic censorship can be a useful principle to deduce other physics. We also found that the attractor behavior is not necessarily related to the specific heat, contrary to the claim by Hiscock and Weems.

NLRB Statutory Interpretation and Chevron Deference in the Appellate Courts

What statutory methods does an appellate court use in reviewing decisions of an administrative agency? In doing this review, are appellate judges more likely to cite to the text or legislative history when they expressly cite the Chevron two-step process versus if they apply a different deference regime? And what role does the opinion author’s race, age, gender, and prior employment at a federal agency or Congress, among other demographic attributes, play in both choice of statutory method and deference regime? This Article explores the answers to these questions using an original dataset of all 199 statutory interpretation cases culled from more than 2,500 cases decided in appellate courts reviewing National Labor Relations Board (“NLRB”) decisions from 1994 through 2018. This analysis concludes that although there are clear partisan trends in which statutory methods Democrat-majority or Republican-majority panels favor, for the most part usage does not differ statistically. Rather, courts regardless of majority party on the court, commonly use text, language canons, substantive canons, legislative history, precedent, policy, and practical considerations to achieve certain aims, such as favoring a particular method when reviewing conservative Board decisions, or when overruling such decisions, or to advance an interpretation that is ideologically consistent with that of the majority. Democrat-majority and Republican-panel differ in their propensity to rule in a pro-employee direction and they are using whatever statutory method is best suited to achieve the end goal, whether it be textual or purposive in nature. The data also reveals that courts specifically citing and using the Chevron two-step process are more cognizant of citing and using the text, language canons, and substantive canons in the writing of the opinion than when they do not specifically cite Chevron, thus suggesting that the choice of the Chevron framework itself may play a role in influencing how judges choose statutory methods. By contrast, those who decline to apply Chevron deference or a similar “reasonableness” standard are more likely to cite legislative history and precedent, perhaps viewing these methods as a substitute to give the opinion greater legitimacy when courts decline to apply Chevron. Further, some interesting bivariate relationships exist between choice of statutory method or deference regime and opinion-author demographic features. White authors sitting with at least one minority colleague are less likely to apply Chevron in overruling liberal Board decisions while judge-authors with congressional experience cite substantive canons more overall. Other insights based on party, race, gender, and prior educational and employment background are discussed in the Article. Although the study is of a single agency — and one of the most politically charged ones at that — it offers fresh insight into how empirical analysis can be used to look beyond the black box of statutory interpretation by federal courts to see what shapes judicial opinions. The Article’s findings also underscore the need for more research on the way that diversity influences judicial decision making on a collegial court.

Insight on collagen self-assembly mechanisms by coupling molecular dynamics and UV spectroscopy techniques

Self-assembly of rat tail collagen type I was investigated by means of turbidity measurements and molecular dynamics simulations. Turbidity curves collected at different pH values show that the rate of aggregation was not linear in dependence from pH, with the fastest kinetics at pH 5.0 and the lowest at neutral pH. MD simulations were carried out on two regions with different hydropathicity, monitoring the aggregation of up to four staggered tropocollagen fragments at different ionic strength. At physiological conditions, association of lowly charged regions occurs more easily than for highly charged ones, the latter seeming to aggregate in a sequential way. The first contacts indicate for both regions that the driving force is hydrophobic, the electrostatic contribution becoming relevant at short distance. The direct inter-tropocollagen H-bonds confirm that fibrillogenesis is driven by loss of surface water from the monomers and involves in large percentage hydroxyproline residues. Low ionic strength dynamics leads to the formation of incorrect assemblies, driven by not shielded pairwise charge interactions.

Minimal spin-one isotriplet dark matter

In this work we present a simple extension of the Standard Model that contains, as the only new physics component, a massive spin-one matter field in the adjoint representation of $SU(2)_{L}$. In order to be consistent with perturbative unitarity, the vector field must be odd under a $Z_{2}$ symmetry. Radiative corrections make the neutral component of the triplet ($V^{0}$) slightly lighter than the charged ones. We show that $V^{0}$ can be the dark matter particle while satisfying all current bounds if it has a mass between $2.8$ and $3.8$ TeV. We present the current limit on the model parameter space from highly complementary experimental constraints including dark matter relic density measurement, dark matter direct and indirect detection searches, LHC data on Higgs couplings to photons and LHC data on disappearing track searches. We show that the two-dimensional parameter space can be substantially covered by disappearing track searches at a future 100 TeV hadron collider, which will probe DM mass upto about 1.2 TeV.

Elastic colloidal monopoles and reconfigurable self-assembly in liquid crystals.

Monopole-like electrostatic interactions are ubiquitous in biology1 and condensed matter2-4, but they are often screened by counter-ions and cannot be switched from attractive to repulsive. In colloidal science, where the main goal is to develop colloidal particles2,3 that mimic and exceed the diversity and length scales of atomic and molecular assembly, electrostatically charged particles cannot change the sign of their surface charge or transform from monopoles to higher-order multipoles4. In liquid-crystal colloids5-7, elastic interactions between particles arise to minimize the free energy associated with elastic distortions in the long-range alignment of rod-like molecules around the particles5. In dipolar6,8, quadrupolar8-12 and hexadecapolar13 nematic colloids, the symmetries of such elastic distortions mimic both electrostatic multipoles14 and the outermost occupied electron shells of atoms7,15,16. Electric and magnetic switching17,18, spontaneous transformations19 and optical control20 of elastic multipoles, as well as their interactions with topological defects and surface boundary conditions, have been demonstrated in such colloids21-23. However, it has long been understood5,24 that elastic monopoles should relax to uniform or higher-order multipole states because of the elastic torques that they induce5,7. Here we develop nematic colloids with strong elastic monopole moments and with elastic torques balanced by the optical torques induced by ambient light. We demonstrate the monopole-to-quadrupole reconfiguration of these colloidal particles by unstructured light, which resembles the driving of atoms between the ground state and various excited states. We show that the sign of the elastic monopoles can be switched, and that like-charged monopoles attract whereas oppositely charged ones repel, unlike in electrostatics14. We also demonstrate the out-of-equilibrium dynamic assembly of these colloidal particles. This diverse and surprising behaviour is explained using a model that considers the balance of the optical and elastic torques that are responsible for the excited-state elastic monopoles and may lead to light-powered active-matter systems and self-assembled nanomachines.

Real-time observation of X-ray-induced intramolecular and interatomic electronic decay in CH2I2

The increasing availability of X-ray free-electron lasers (XFELs) has catalyzed the development of single-object structural determination and of structural dynamics tracking in real-time. Disentangling the molecular-level reactions triggered by the interaction with an XFEL pulse is a fundamental step towards developing such applications. Here we report real-time observations of XFEL-induced electronic decay via short-lived transient electronic states in the diiodomethane molecule, using a femtosecond near-infrared probe laser. We determine the lifetimes of the transient states populated during the XFEL-induced Auger cascades and find that multiply charged iodine ions are issued from short-lived (∼20 fs) transient states, whereas the singly charged ones originate from significantly longer-lived states (∼100 fs). We identify the mechanisms behind these different time scales: contrary to the short-lived transient states which relax by molecular Auger decay, the long-lived ones decay by an interatomic Coulombic decay between two iodine atoms, during the molecular fragmentation.

Photothermal effects on protein adsorption dynamics of PEGylated gold nanorods

The effect of thermoplasmonic heating on the dynamics of the protein corona around polyethylene glycol (PEG) coated gold nanorods (GNRs) is reported. GNRs were surface-modified with densely packed shells composed of thiolated PEGs bearing carboxyl and/or amine end-terminal groups, which led to negatively, positively or neutral charged GNRs. The three types of PEGylated GNRs, although with subtle differences among them, present weak interactions (binding dissociation constants in the μM range) with the model protein bovine serum albumin (BSA), as determined by different methods including gel electrophoresis, laser Doppler anemometry and isothermal titration calorimetry (ITC). In general, plasmonic photothermal heating significantly changed the composition of the protein corona around GRNs, particularly, on the positively charged ones. Moreover, a pre-formed BSA corona on the PEGylated GNRs further decreased their already reduced uptake by cells. However, photothermal treatment of BSA-coated GNRs only produced a significant decreased internalization in the case of non-PEGylated control samples. Overall, our results indicate that differently surface charged PEGylations on GNRs affects the dynamics of protein corona formation, which is particularly relevant after photothermal treatment. Such effects are nonetheless non-significant concerning cellular uptake.

Kinetics of spontaneous microgels adsorption and stabilization of emulsions produced using microfluidics

The aim of the paper is to examine the adsorption kinetics of soft microgels and to understand the role of fundamental parameters such as electrostatics and deformability on the process. This knowledge is further exploited to produce microgel-stabilized emulsions using a co-flow microfluidic device.Uncharged microgels made of poly(N-isopropylacrylamide) are synthesized with variable cross-linker contents, and charged ones are produced by introducing pH sensitive co-monomers during the synthesis. The study is carried out by measuring the microgels adsorption kinetics by means of the pendant drop method. The surface pressure is derived from the previous results as a function of time and is measured as a function of the area compression using a Langmuir trough. Emulsions are produced using a microfluidic device varying the microgels concentration and their stability is visually assessed.The microgels deformability as well as higher particle concentrations favour their adsorption. The adsorption is not governed by diffusion, it is cooperative and irreversible. Conversely, the kinetics is slowed down for increasing cross-linking density. The presence of charges slows down the kinetics of adsorption. In the presence of electrolyte, the kinetics accelerates and becomes similar to the one of neutral microgels. The original features of microgel adsorption is highlighted and the differences with adsorption of polymers, star polymers, proteins, and polyelectrolytes are emphasized. Taking benefit from the adsorption kinetics, the required formulation conditions for producing microgel-stabilized emulsions using a co-flow microfluidic device are derived.There exists a critical concentration above which microgels spontaneously adsorb in a sufficient way to decrease the interfacial tension. This critical microgel concentration increases with the cross-linking density and is higher for charged microgels. Whatever the kinetics, the same surface pressure is finally reached. This peculiar behaviour is likely a consequence of the presence of dangling chains in the as-prepared microgels. Consequently, a microgel excess is required to produce emulsions using microfluidics where adsorption has to be spontaneous.