Showing papers in "Current Opinion in Colloid and Interface Science in 2018"
TL;DR: Halloysite is natural tubular clay suitable as a component of biocompatible nanosystems with specific functionalities as discussed by the authors, and the selective modification of halloysite inner/outer surfaces can be achieved by exploiting supramolecular and covalent interactions resulting in controlled colloidal stability adjusted to the solvent polarity.
Abstract: Halloysite is natural tubular clay suitable as a component of biocompatible nanosystems with specific functionalities. The selective modification of halloysite inner/outer surfaces can be achieved by exploiting supramolecular and covalent interactions resulting in controlled colloidal stability adjusted to the solvent polarity. The functionalized halloysite nanotubes can be employed as reinforcing filler for polymers as well as carriers for the sustained release of active molecules, such as antioxidants, flame-retardants, corrosion inhibitors, biocides and drugs. The tubular morphology makes halloysite a perspective template for core-shell metal supports for mesoporous catalysts. The catalysts can be incorporated with selective and unselective metal binding on the nanotubes' outer surface or in the inner lumens. Micropatterns of self-assembled nanotubes have been realized by the droplet casting method. The selective modification of halloysite has been exploited to increase the nanotubes' ordering in the produced patterns. Pickering emulsions, induced by the self-assembly of halloysite nanotubes on oil-water interface, can be used for petroleum spill bioremediation and catalysis.
305 citations
TL;DR: In this article, the authors explored the fouling mechanisms based on classical fouling models, and on oil droplet behaviors (such as droplet deposition, accumulation, coalescence and wetting) on the membranes.
Abstract: Oily wastewater is an extensive source of pollution to soil and water, and its harmless treatment is of great importance for the protection of our aquatic ecosystems. Membrane filtration is highly desirable for removing oil from oily water because it has the advantages of energy efficiency, easy processing and low maintenance cost. However, membrane fouling during filtration leads to severe flux decline and impedes long-term operation of membranes in practical wastewater treatment. Membrane fouling includes reversible fouling and irreversible fouling. The fouling mechanisms have been explored based on classical fouling models, and on oil droplet behaviors (such as droplet deposition, accumulation, coalescence and wetting) on the membranes. Membrane fouling is dominated by droplet-membrane interaction, which is influenced by the properties of the membrane (e.g., surface chemistry, structure and charge) and the wastewater (e.g., compositions and concentrations) as well as the operation conditions. Typical membrane antifouling strategies, such as surface hydrophilization, zwitterionic polymer coating, photocatalytic decomposition and electrically enhanced antifouling are reviewed, and their cons and pros for practical applications are discussed.
208 citations
TL;DR: In this paper, the physics behind the inkjet printing process is explored by combining state-of-the-art experimental and numerical techniques, and the fundamental knowledge gained is crucial for the further development of the Inkjet printing technology which became mature in graphical printing applications and plays a key role in many emerging new industrial and medical applications.
Abstract: The inkjet printing process involves a chain of processes in many physical domains at different length and time scales. The final goal is the deposition of droplets of all kinds of fluids with any desired volume and velocity. To comply with the increasing and diverging requirements for today's inkjet technology, a fundamental understanding of the underlying processes is very important. By combining state of the art experimental and numerical techniques, the physics behind the chain of processes are being explored. The fundamental knowledge gained is crucial for the further development of the inkjet printing technology which became mature in graphical printing applications and plays a key role in many emerging new industrial and medical applications.
122 citations
TL;DR: In this paper, the authors review progress made in particular for complex fluid-fluid interfaces where rheological stresses, peculiar to the interface, play an important role, and discuss how simple complex flows, such as thin film and drainage flows, offer a first step up in complexity and seem to present a good benchmark problem for testing constitutive equations and the interplay between transport phenomena, interfacial rheology and the changes in state variables.
Abstract: Complex fluid-fluid interfaces play an important role in a variety of application domains, from emulsion and foam stability, to thin films in biomedical applications, to coating flow phenomena. The current work reviews progress made in particular for interfaces where rheological stresses, peculiar to the interface, play an important role. The developments made in the area of constitutive modeling are briefly reviewed to clarify which material functions can be measured. For shear rheometry, progress in analyzing the flow field in the measurement device has been key, combined with advances in control over surface concentration and microstructural evaluation. For dilation/compressional rheometry much work has been done on separating changes in the surface tension from the extra rheological stresses. Finally, we discuss how “simple complex flows”, such as thin film and drainage flows, offer a first step up in complexity and seem to present a good benchmark problem for testing constitutive equations and the interplay between transport phenomena, interfacial rheology and the changes in state variables.
107 citations
TL;DR: In this article, the authors reviewed the recent developments in the field of oppositely charged polyelectrolyte-surfactant complexes (PESCs) and found that PESCs are typically not static entities but instead highly dynamic systems and recent neutron spin-echo (NSE) measurements indicate that the local dynamics of polyelectron chains is only little affected by the incorporation within such aggregates.
Abstract: Recent developments in the field of oppositely charged polyelectrolyte-surfactant complexes (PESCs) have been reviewed. Among the many developments in that field in particular very interesting is certainly the discovery of still new types of structural arrangements that arise from the complexity of the prevailing interactions, both in terms of electrostatics, as well as steric and specific interactions. More complex structures often arise from the architecture of the polyelectrolyte, such as the use of block copolymers or hydrophobically modified polyelectrolytes. However, also the surfactant plays a role in the PESC structure and for instance bilayer forming surfactants can be induced by polyelectrolyte to form multilamellar assemblies. Of course, PESCs may exhibit responsiveness to changes of pH, temperature, chemical environment etc. and this even in a complex fashion as the polyelectrolyte and surfactant may respond here in a different fashion. Interesting observations also concern the control of rheological properties by PESCs that depend strongly on the properties of the polyelectrolyte and the extension of the formed mixed aggregates, as well as their bridging. An old topic is coacervate formation in such systems, but one that currently receives renewed attention, as various aspects here are still not fully understood and at the same time they are very promising for further applications in separation/sequestration. Often overlooked is the fact that PESCs are typically not static entities but instead highly dynamic systems and recent neutron spin-echo (NSE) measurements indicate that the local dynamics of polyelectrolyte chains is only little affected by the incorporation within such aggregates. Therefore PESCs are still a highly fascinating class of self-assembled structures, where a large number of interesting developments may still be expected in the future.
83 citations
TL;DR: Nanostructured surfaces are called promising to control bacterial adhesion and biofilm formation as discussed by the authors, which can be made on the basis of periodic or random occurrence of nanostructure features, although often nanostructures are microstructured due to merging of their nanofeatures.
Abstract: Nanostructured surfaces are called “promising” to control bacterial adhesion and biofilm formation. Initial adhesion is followed by emergence of surface-programmed bacterial properties and biofilm growth. A easy distinction between nanostructured surfaces can be made on basis of periodic- or random-occurrence of nanostructured features, although often nanostructured surfaces are microstructured due to merging of their nanofeatures. Characterization of nanostructured surfaces is not trivial due to the myriad of different nanoscaled morphologies. Both superhydrophobic and hydrophilic, nanostructured surfaces generally yield low bacterial adhesion. On smooth surfaces, bacteria deform when adhering, causing membrane surface tension changes and accompanying responses yielding emergent properties. Adhesion to nanostructured surfaces, causes multiple cell wall deformation sites when bacteria are adhering in valleys, while in case of hill-top adhesion, highly localized cell wall deformation occurs. Accordingly, bacterial adhesion to nanostructured surfaces yields emergent responses that range from pressure-induced EPS production to cell wall rupture and death, based upon which nanostructured surfaces are consistently called “promising” for bacterial adhesion and biofilm control. Other promising features of nanostructured surfaces are increased antibiotic housing, thermal effects and photo-induced ROS production, but the latter two promises are largely based on properties of suspended nanoparticles and may not hold when particles are comprised in nanostructured coatings or materials. Moreover, in order to bring nanostructured coatings and materials to application, experiments are needed that go beyond the current limit of the laboratory bench.
76 citations
TL;DR: This review highlights recent advances in the self-assembly of short amphiphilic peptides, focusing on the strategies to manipulate the involved non-covalent interactions as well as the consequent supramolecular architectures.
Abstract: Peptide self-assembly is an effective way to construct well-ordered nanostructures for biomedical applications. Given that short peptide length always facilitates large-scale production for future applications and the easy establishment of structure-property relationship, this review highlights recent advances in the self-assembly of short amphiphilic peptides, focusing on the strategies to manipulate the involved non-covalent interactions as well as the consequent supramolecular architectures. One representative strategy is based on molecular design, in which amino acid substitution, sequence variation, terminal capping, molecular geometry, and amino acid chirality are considered. Another important strategy that varies solution conditions (pH, solvents, enzymes, and metal ions) is also discussed. A variety of self-assembled pep1tide nanostructures and nanomaterials have been achieved therefrom and more importantly, the advances make the prediction of peptide self-assembly increasingly feasible based on a certain class of peptide sequences and solution conditions. Additionally, their applications as antibiotics and templates for nanofabrication, mainly from the work of our group, demonstrate the importance of the surface properties and morphologies of self-assemblies to practical applications. Following previous studies, future endeavor in this field is suggested to focus on designing more peptide sequences with functional motifs not only to summarize general rules to predict self-assembly but also to realize practical applications.
65 citations
TL;DR: In this paper, a survey of recent literature on wetting phenomena reveals that there is a fast-growing interest in wetting of soft or deformable substrates, due to its potential applications in many industrial, technical and biological processes.
Abstract: A survey of recent literature on wetting phenomena reveals that there is a fast-growing interest in wetting of soft or deformable substrates, due to its potential applications in many industrial, technical and biological processes. Unlike rigid substrates, a droplet deposited on a soft substrate deforms the substrate via a combination of the normal component of surface tension and the Laplace pressure, i.e. by capillary force and the action of disjoining pressure. In turn, the capillary and disjoining pressure-induced substrate deformation affects the wetting phenomena on the substrate. In this review, we summarize recent achievements on static and dynamic wetting of soft substrates and provide an outlook to future progress. In static wetting, theoretical, numerical and experimental investigations of capillary and disjoining pressure-induced substrate deformation are introduced, and corresponding effects on contact angle and contact angle hysteresis are discussed. In dynamic wetting, the influence of substrate stiffness on spontaneous wetting, droplet impact dynamics, and other types of forced wetting and dewetting is considered. Finally, other interesting capillarity-controlled phenomena occurring on soft and soft-like substrates are briefly introduced.
63 citations
TL;DR: In this article, a review of recent literature examining ferrofluid wetting phenomena and outline novel wetting related applications is presented. But the authors focus on interpretation of ferro-fluid contact angles, which are commonly used to characterize wetting properties.
Abstract: Ferrofluids are liquids exhibiting remarkably strong response to magnetic fields, which leads to fascinating properties useful in various applications. Understanding the wetting properties and spreading of ferrofluids is important for their use in microfluidics and magnetic actuation. However, this is challenging as magnetically induced deformation of the ferrofluid surface can affect contact angles, which are commonly used to characterize wetting properties in other systems. In addition, interaction of the magnetic nanoparticles and solid surface at nanoscale can have surprising effects on ferrofluid spreading. In this review we discuss these issues with focus on interpretation of ferrofluid contact angles. We review recent literature examining ferrofluid wetting phenomena and outline novel wetting related ferrofluid applications. To better understand wetting of ferrofluids, more careful experimental work is needed.
62 citations
TL;DR: Wetting and spreading are familiar phenomena in nature and commonly observed in our daily life, and of great significance for basic scientific researches as well as providing solutions to the cutting-edge technical applications as mentioned in this paper.
Abstract: Wetting and spreading are familiar phenomena in nature and commonly observed in our daily life, and of great significance for basic scientific researches as well as providing solutions to the cutting-edge technical applications. Recent decades, learning from Nature, unique wetting and spreading behaviors have been bio-mimetically realized through the construction of artificial materials, which have promoted the ongoing development of relating areas like the liquid transportation, spraying, cleaning, and painting in industry and agriculture, and even influenced the way of our daily life. A systemic and timely review is therefore necessary to summary the existing novel researches and provide some idea of the next tide in leading the scientific trend. Here, we will present how the bio-inspired materials with special wettabilities have been integrated into traditional materials or devices to improve their wetting and spreading performances. The progresses of both fundamental theories and cutting-edge applications that reported in recent years are briefly reviewed. Basing on the impacting state of the liquid, the wetting and spreading progresses have been divided into 3 categories: which include interaction between the solid surfaces with the static contacting drop, dynamic impacting drop, and overflowing fluid. At the end of the review, some challenges and development tendency of the ongoing wetting and spreading research are highlighted.
57 citations
TL;DR: Emphasis will be put on the rational design of intermolecular interactions between drugs and peptides, in vitro and in vivo drug delivery and antitumor therapeutic effects and the key challenges and promising perspectives of such kind of peptide-mediated assembled nanodrugs for both technical advances and potential clinical translation.
Abstract: In this review we consider assembled nanodrugs as a type of nanoscale drugs formed by molecular self-assembly and associated with precise organization of multiple non-covalent interactions. Their typical feature is that the drug itself is considered as one of the building blocks with flexibly interplaying interaction for supramolecular assembly and nanostructure formation with robust stability and high loading efficiency in a controlled and tunable way. The super stability with retained function results from the “hydrophobic effect” of supramolecular self-assembly of peptides and drugs. It is the hydrophobic effect responsible for both colloidal stability and circulation stability in body against dilution and blood-flow shearing. The assembled nanodrugs are distinguished from conventional ones with encapsulation of the drugs in delivery nanocarriers. We will focus on how peptides and peptide-conjugates can be designed for controlling and mediating the formation of the assembled nanodrugs. Emphasis will be put on the rational design of intermolecular interactions between drugs and peptides, in vitro and in vivo drug delivery and antitumor therapeutic effects. Finally, we will discuss the key challenges and promising perspectives of such kind of peptide-mediated assembled nanodrugs for both technical advances and potential clinical translation.
TL;DR: Recent advances in understanding and controlling protein conformation on the surface of synthetic materials are highlighted, which represents a critical step towards the rational design of biotic–abiotic interfaces in biomedical and biotechnological applications.
Abstract: Understanding the behavior of proteins at material interfaces has become increasingly important as the intersection between the biological and synthetic worlds continues to grow. By inducing changes in protein structure, interactions with materials may lead to a loss of function and/or biological activity, as well as undesirable cellular interactions in vivo, including the foreign body reaction to implantable materials. Despite extensive research, the understanding of the mechanisms that lead to protein conformational changes on surfaces remains incomplete. Here, we highlight recent advances in understanding and controlling protein conformation on the surface of synthetic materials, including nanomaterials, polymer films and brushes, metal coatings and particles, and graphitic materials. We also review developments in the use of biophysical and computational methods for characterizing the structure of proteins at solution–solid interfaces. These approaches have provided important new insights into the physico-chemical factors that control protein conformation in near-surface environments, which represents a critical step towards the rational design of biotic–abiotic interfaces in biomedical and biotechnological applications.
TL;DR: In this article, the main mechanism used nowadays, i.e. cross effect, for DNP enhanced solid-state NMR was described and the typical protocols of sample formulation leading to effective DNP surface enhancements and the key experimental factors in performing DNP SENS experiments.
Abstract: Dynamic Nuclear Polarization Surface Enhanced NMR spectroscopy has been demonstrated to significantly improve NMR sensitivity on materials by 1 to 2 orders of magnitude at high magnetic fields. The preferential surface enhancement also allows for selectively probing the solid surface. In this review, we will briefly describe the main mechanism used nowadays, i.e. cross effect, for DNP enhanced solid-state NMR. We will show the typical protocols of sample formulation leading to effective DNP surface enhancements and the key experimental factors in performing DNP SENS experiments. Other important developments in DNP, i.e. shielded polarizing agents for reactive surfaces, hyperpolarizing solid matrices, and high-temperature and high-field DNP, will be discussed as well. Finally, we close the review with a short summary and our perspectives on the directions of future developments in this field.
TL;DR: In this paper, the authors summarize the recent progress on the collectively dynamic self-assembly systems of synthetic colloid motors sorted by various triggers of self-propulsion and external fields (such as chemicals, light, electric fields, and acoustic fields), ranging from the propulsion to stimuli of collective selfassembly.
Abstract: Collectively dynamic self-assembly arising from the living mobility is the fundamental process of lives. Inspired by collective behaviors of living systems, collective motion and self-assembly of synthetic colloid motors have been brought into focus due to high performance and emerging phenomena beyond the power of single colloid motor. Here, we summarize the recent progress on the collectively dynamic self-assembly systems of synthetic colloid motors sorted by various triggers of self-propulsion and external fields (such as chemicals, light, electric fields, and acoustic fields), ranging from the propulsion to stimuli of collective self-assembly. The typical physical phenomena are presented, including phase separation, clustering, and giant number fluctuations. The collectively dynamic self-assembly of colloid motors are expected to provide unlimited opportunities to various applications with continuous innovation both in the design of synthetic colloid motors and the modulation of collectively dynamic self-assembly.
TL;DR: In this paper, a review of self-assembling polymer nanocomposites and their biomedical applications is presented, highlighting the latest achievements in developing biointerface controlling cell behaviors, biosensors for diagnosis, drug vehicles and wound dressings.
Abstract: Polymer nanocomposites have attracted great scientific and industrial interests in recent decades because of their unique properties emerging from the combination of polymer and inorganic nanomaterial. The construction of polymer nanocomposites into hierarchical nanostructures via self-assembly strategies offer great advantages in creating functional materials with advanced properties for biomedical applications. This review covers recent progresses in the self-assembled polymer nanocomposites and their biomedical applications. We firstly briefly discuss some common methods for the self-assembly of polymer nanocomposites. Then, the latest achievements are highlighted in developing biointerface controlling cell behaviors, biosensors for diagnosis, drug vehicles and wound dressings. Without a doubt, polymer nanocomposite self-assemblies have become potential candidates in the development of practical biomedical devices.
TL;DR: In this paper, the authors review the development of dielectrowetting, its origins, the statics and dynamics of the dielectric liquid droplets, and the applications in microfluidics and optofluidics.
Abstract: Liquid dielectrophoresis is a bulk force acting on dipoles within a dielectric liquid inside a non-uniform electric field. When the driving electrodes are interdigitated, bulk liquid dielectrophoresis is converted to an interface-localised form capable of modifying the energy balance at an interface. When the interface is a solid-liquid one, the wetting properties of a surface are modified and this approach is known as dielectrowetting. Dielectrowetting has been shown to provide the ability to reversibly modify the contact angle of a liquid droplet with the application of voltage, the strength of which is controlled by the penetration depth of the non-uniform field and permittivities of the fluids involved. Importantly, dielectrowetting provides the ability to create thin liquid films, overcoming the limitation of contact angle saturation present in electrowetting. In this paper, we review the development of dielectrowetting - its origins, the statics and dynamics of dielectrowetted droplets, and the applications of dielectrowetting in microfluidics and optofluidics. Recent developments in the field are also reviewed showing the future directions of this rapidly developing field.
TL;DR: In this paper, the performance of dynamic nuclear polarization (DNP) surface-enhanced NMR spectroscopy (SENS) is reviewed for alumina, silica, and ordered mesoporous carbon (OMC) materials, with vastly different surface areas.
Abstract: The efficacy of dynamic nuclear polarization (DNP) surface-enhanced NMR spectroscopy (SENS) is reviewed for alumina, silica, and ordered mesoporous carbon (OMC) materials, with vastly different surface areas, as a function of the biradical concentration. Importantly, our studies show that the use of a “one-size-fits-all” biradical concentration should be avoided when performing DNP SENS experiments and instead an optimal concentration should be selected as appropriate for the type of material studied as well as its surface area. In general, materials with greater surface areas require higher radical concentrations for best possible DNP performance. This result is explained with the use of a thermodynamic model wherein radical-surface interactions are expected to lead to an increase in the local concentration of the polarizing agent at the surface. We also show, using plane-wave density functional theory calculations, that weak radical-surface interactions are the cause of the poor performance of DNP SENS for carbonaceous materials.
TL;DR: This paper reviews the understanding that has been achieved by interpreting blood wetting, spreading and drying when in contact, ex-vivo, with non-coated surfaces and highlights the applications with the most up to date research, future perspectives, and the need of advancing further.
Abstract: Investigation of the physical phenomena involved in blood interactions with real surfaces present new exciting challenges. The fluid mechanical properties of such a fluid is singular due its non-Newtonian and complex behaviour, depending on the surrounding ambient conditions and the donor/victim's blood biological properties. The fundamental research on the topic remains fairly recent; although it finds applications in fields such as forensic science, with bloodstain pattern analysis, or biomedical science with the prospect of disease detection from dried blood droplets. In this paper, we review the understanding that has been achieved by interpreting blood wetting, spreading and drying when in contact, ex-vivo, with non-coated surfaces. Ultimately, we highlight the applications with the most up to date research, future perspectives, and the need of advancing further in this topic for the benefit of researchers, engineers, bloodstain pattern analysts, and medical practitioners.
TL;DR: In this article, the role of interfacial phenomena in the interactions between inhaled solid particles with different properties (size, structure, surface characteristics) and air/liquid interface of the alveolar region of the lungs is highlighted and discussed.
Abstract: The paper highlights and discusses the role of interfacial phenomena in the interactions between inhaled solid particles with different properties (size, structure, surface characteristics) and air/liquid interface of the alveolar region of the lungs. The greatest attention is paid to man-made nanosized and nanostructured particles which often belong to the class of “engineered particles”. Their applications in several novel technologies may be associated with accidental particle release to the air and formation of potentially harmful aerosol. Extraordinary, dynamic surface-active properties of the lung surfactant, which are responsible for several physiological functions - including the pulmonary mass transfer - may be altered by such inhaled particles in a material- and dose-dependent manner. Certain effects can be assessed by specialized experimental in vitro methods allowing predictions of possible in vivo interactions. On the other hand, interactions with the lung surfactant can modify the original properties of inhaled particles which in turn will influence their bioavailability or toxicity. All mentioned effects are dependent on particles properties as proven by numerous studies, however such results should be carefully judged due to essential differences in experimental methodology used. The paper also discusses some ideas related to the practical meaning of discussed effects for novel concepts of pulmonary drug delivery by inhalation.
TL;DR: An overview is provided of the current understanding of the interplay between AMP aggregation and antimicrobial effects, including the role of oligomerization and self-assembly on membrane interactions and antimacterial effects, AMP interactions with amyloid-forming peptides/proteins, AMPs self-assemblies as antimicrobial biomaterials, and AMP-induced flocculation of bacteria and bacterial lipopolysaccharides as a novel pathway for confinement of infection and inflammation.
Abstract: With a rapidly growing number of bacterial strains displaying resistance against conventional antibiotics, the development of novel types of antimicrobial agents represents an important health challenge. Antimicrobial peptides (AMPs) has attracted interest in this context, as these can be designed to display potent broad-spectrum antimicrobial as well as anti-inflammatory effects, but simultaneously low toxicity against human cells. Much of the work on AMPs has been focused on membrane interactions of monomeric AMPs, and how these can be controlled by peptide design to obtain selective disruption of bacterial membranes. However, a growing body of research has demonstrated that AMPs offer opportunities as antimicrobials beyond this through their self-assembly. An overview is therefore provided of the current understanding of the interplay between AMP aggregation and antimicrobial effects, including the role of oligomerization and self-assembly on membrane interactions and antimicrobial effects, AMP interactions with amyloid-forming peptides/proteins, AMP self-assemblies as antimicrobial biomaterials, and AMP-induced flocculation of bacteria and bacterial lipopolysaccharides as a novel pathway for confinement of infection and inflammation.
TL;DR: Recent progress in modeling and experimental studies of Marangoni transport induced by the deposition of surfactant-containing microliter drops and liquid aerosols (picoliter drops) onto a fluid interface are reviewed, and the roles of key system variables are identified.
Abstract: Understanding the fundamentals of surface transport on thin viscous films has important application in pulmonary drug delivery. The human lung contains a large-area interface between its complex fluid lining and inhaled air. Marangoni flows driven by surface tension gradients along this interface would promote enhanced distribution of inhaled therapeutics by carrying them from where they are deposited in the upper airways, along the fluid interface to deeper regions of the lung. Motivated by the potential to improve therapies for acute and chronic lung diseases, we review recent progress in modeling and experimental studies of Marangoni transport induced by the deposition of surfactant-containing microliter drops and liquid aerosols (picoliter drops) onto a fluid interface. The roles of key system variables are identified, including surfactant solubility, drop miscibility with the subphase, and the thickness, composition and surface properties of the subphase liquid. Of particular interest is the unanticipated but crucial role of aerosol processing to achieve Marangoni transport via phospholipid vesicle dispersions, which are likely candidates for a biocompatible delivery system. Progress in this field has the potential to not only improve outcomes in patients with chronic and acute lung diseases, but also to further our understanding of surface transport in complex systems.
TL;DR: In this article, a review of recent advances in kinetic and dynamic studies at the air/water interface using specular neutron reflectometry is presented, with a perspective on current capabilities and future developments that will result from further developments in instrumentation and sample environment.
Abstract: This review addresses significant recent advances in kinetic and dynamic studies at the air/water interface using specular neutron reflectometry. A step change in the capabilities to resolve these processes in systems related to soft matter, biophysics, environment and health has been delivered primarily by the FIGARO instrument at the Institut Laue-Langevin. It is now routinely carried out to resolve the surface excess of single-component, deuterated monolayers on the second time scale and the interfacial composition of binary mixtures where only one component is deuterated on the minute time scale. This resource has been exploited extensively in the last few years to provide new insight into the kinetics of oxidation of monolayers targeted from the gas phase and the adsorption of various types of molecules from solution as well as the dynamic molecular interactions of systems under continuous flow and during repeated compression/expansion cycles of a Langmuir trough. A perspective is given on current capabilities and future developments that will result from further developments in instrumentation and sample environment.
TL;DR: In this article, a review of the most recent developments on the studies of the interfacial shear rheology of fluid/fluid interfaces, analyzing the strength and weakness of different approaches, is presented.
Abstract: For many years the determination of the shear viscosity of interfacial layers has been source of strong controversy. This is mainly because different techniques provided different values of such parameter, which leads in many cases to a puzzling interpretation of the experimental results. One possible explanation of this is the non-correct analysis of the hydrodynamic conditions of the measurement and, in particular, the assumption of some approximations that may not be necessarily valid in all cases. The introduction of hydrodynamic consideration in the study of interfacial shear rheology has helped to clarify some of the existing discrepancies between measurements performed using different devices, thus allowing one to establish clearly the viscosity range in which different techniques can operate with enough sensitivity for determining the interfacial shear viscosity. This review puts in perspective the most recent developments on the studies of the interfacial shear rheology of fluid/fluid interfaces, analyzing the strength and weakness of the different approaches.
TL;DR: The literature in this field almost doubled for the last few years and recent articles are discussed in this paper, where all the systems are divided into two groups of the layers of solid and soft particles depending on the influence of the particle deformability on surface properties, and in the latter case the peculiarities of surface dilational rheological properties of adsorbed and spread layers of polylelctrolyte/surfactant aggregates, solid particles grafted by polymers, polymer microgels, and protein fibrils and micro gels are briefly discussed together
Abstract: Application of the methods of the dilational surface rheology to adsorbed and spread layers of nano- and microparticles at liquid – fluid interfaces gives insight in the structure and formation mechanism of the layers. This is especially important in view of the limited applicability of standard experimental methods of the interface science to heterogeneous surface layers. The literature in this field almost has doubled for the last few years and recent articles are discussed in this review. All the systems are divided into two groups of the layers of solid and soft particles depending on the influence of the particle deformability on surface properties. In the latter case the peculiarities of surface dilational rheological properties of adsorbed and spread layers of polylelctrolyte/surfactant aggregates, solid particles grafted by polymers, polymer microgels, and protein fibrils and microgelsare briefly discussed together with the merits and drawbacks of the existing experimental methods of the surface dilational rheology.
TL;DR: This review highlights the recent progress of porous and responsive hydrogels used for cell encapsulation towards cell therapy, including the treatment of several diseases, such as diabetes mellitus, cancer, neuro disorders, cardiac diseases and bone injuries.
Abstract: Cell therapy is an emerging and promising regenerative approach by cell replacement for the treatment of diseases or injuries. Hydrogels, featuring high biocompatibility, tunable physicochemical properties, controllable structures, and multiple functionalization possibilities, have been developed as most-frequently-used cell reservoirs. Aiming at treating diseases or injuries with high efficiency, a series of porous and responsive hydrogels have been fabricated for the encapsulation of therapeutic cells. These cell-laden hydrogels have been applied in a broad range of pre-clinical researches of which results have demonstrated hopeful prospects in cell therapy. In this review, we highlight the recent progress of porous and responsive hydrogels used for cell encapsulation towards cell therapy. The hydrogels used for cell therapy are firstly classified. The porosity fabrication strategies of hydrogels are summarized and discussed. The responsive functionalities of hydrogels are surveyed, focusing on temperature-sensitivity, photo-sensitivity, pH-responsivity and biomolecule-sensitivity. Moreover, preclinical researches of hydrogels towards cell therapy, including the treatment of several diseases, such as diabetes mellitus, cancer, neuro disorders, cardiac diseases and bone injuries are discussed.
TL;DR: In this paper, the authors highlight recent developments and limitations in both experimental and computational research focusing on the liquid-solid interface and make the case that coupling of experiments and simulations is pivotal to mitigate methodological shortcomings and address open problems pertaining to charged interfaces.
Abstract: Surface charge controls many static and dynamic properties of soft matter and micro/nanofluidic systems, but its unambiguous measurement forms a challenge. Standard characterization methods typically probe an effective surface charge, which provides limited insight into the distribution and dynamics of charge across the interface, and which cannot predict consistently all surface-charge-governed properties. New experimental approaches provide local information on both structure and transport, but models are typically required to interpret raw data. Conversely, molecular dynamics simulations have helped showing the limits of standard models and developing more accurate ones, but their reliability is limited by the empirical interaction potentials they are usually based on. This review highlights recent developments and limitations in both experimental and computational research focusing on the liquid-solid interface. Based on recent studies, we make the case that coupling of experiments and simulations is pivotal to mitigate methodological shortcomings and address open problems pertaining to charged interfaces.
TL;DR: A brief overview on factors affecting toxicity of amphiphilic peptides against tumor and non-malignant cells is provided, and how such peptides can be combined with conjugation moieties or drug delivery systems for increased anticancer effects is described.
Abstract: Following considerable research efforts on antimicrobial effects by cationic and amphiphilic peptides during the last couple of decades, increasing focus has recently been placed on additional host defense and other biological functions by such peptides, such as anti-inflammatory and anticancer effects. Regarding the latter, it has been increasingly understood that amphiphilic peptides present interesting opportunities not only for reaching selective cancer cell toxicity, but also for promoting uptake of other anticancer therapeutics and of nanopariculate delivery systems containing such drugs. While there is an emerging understanding of the direct antimicrobial function of amphiphilic peptides through bacterial membrane destabilization, the mechanisms underlying their anticancer effects remain less clear. Here, we therefore provide a brief overview on factors affecting toxicity of amphiphilic peptides against tumor and non-malignant cells, and also describe how such peptides can be combined with conjugation moieties or drug delivery systems for increased anticancer effects.
TL;DR: In this paper, the authors provide an update on some studies in the field carried out mainly by the authors and collaborators, including the optimization of samples towards more biologically relevant model systems and include the use of more complex lipid mixtures up to natural extracts.
Abstract: Cells, the basic units of living organisms, are well delineated and separated from the external environment by membranes. Capable of both enclosing the cellular constituents and allowing exchanges with the outside world, these membranes are only a few nanometers thick. All the membranes in a human body cover an area of a few hectares, but account for only a small part of our mass. To study the dynamics and function of these amazing objects, physicists first seek to understand their structure. This involves experiments on model systems, simpler and better controlled than real membranes, and can profit from a probe that is able to access different scales of size and time: thermal neutrons. Since the pioneering work in the seventies on cell membrane structure by neutron scattering, developments driven by constantly improving neutron instrumentation, coupled with development of measurement and analysis methods, have involved both the optimization of samples towards more biologically relevant model systems and include the use of more complex lipid mixtures up to natural extracts. This review does not have the ambition to address the large number of contributions from all the groups working in this area in research laboratories and neutron facilities. It gives an update on some studies in the field carried out mainly by the authors and collaborators.
TL;DR: In this article, the authors review recent research efforts aiming either to design surfaces or to design actuation mechanisms to achieve an extended range of electrowetting-induced apparent wettability modification.
Abstract: By combining the fascinating wetting properties of geometrically patterned surfaces with the versatility of electrowetting in modifying the apparent material wettability, novel systems with significant technological applications can arise. Applications, however, are limited by irreversible transitions between highly mobile and sticky wetting states. We review recent research efforts aiming either to design surfaces or to design actuation mechanisms to achieve an extended range of electrowetting-induced apparent wettability modification.
TL;DR: In this article, the authors highlight the properties of magnetic surfactants as well as their self-assembly behavior and applications and highlight the applications of magnetic self-assembling.
Abstract: Self-assembly of magnetic surfactants has developed rapidly in physical chemistry, materials science and biomedicine science. By incorporating paramagnetic component within the cation or anion, magnetic surfactants exhibit a strong magnetic response and enhanced hydrophobicity. By subtle design, magnetic surfactants could self-assemble to generate various magnetic aggregates, biomaterials and nano-materials, such as the bacillus-shaped bilayer vesicle, thermotropic liquid crystals, DNA hybrid nanosphere as well as magnetic fullerene, graphene, mesoporous silica and Au nanoparticles. This review highlights the properties of magnetic surfactants as well as their self-assembly behavior and applications.