Offshore oil spills, industrial oily wastewater, and domestic oil pollution are some of the most serious global challenges, and are leading environmental causes of morbidity and mortality. Nanofiber ...membrane materials manufactured
via
electrostatic spinning for oil/water separation have become one of the emerging technologies to treat oil/water emulsions. Here, we give a comprehensive review of current progress on electrospinning nanofibers for oil/water separation to promote the field's advancement. Typical examples of hydrophilic-oleophobic, hydrophobic-oleophilic, and special wettability nanofiber membranes are systematically summarized. The effects of material selection, fiber production processes, and subsequent modifications on the membrane performance are compared and discussed. Potential shortcomings of various types of separation membranes and the potential solutions are provided. The review concludes with a summary and outlook on future directions and innovations in electrospinning nanofibers and membranes for oil/water separation.
This paper gives a current summary of research advances in the field of electrospun nanofibers and nanofiber membranes for oil/water separation. And a discussion about the future field development is given.
Nanofiltration membrane plays an increasingly important role in many industrial applications, such as water treatment and resource recovery. The performance of the smart nanofiltration membrane is ...largely controlled by pore size, the Donnan effect, and surface wettability, which are determined by the function of stimuli‐responsive components. Smart membranes, which contain stimuli‐responsive components, are capable of changing their physical and chemical properties in response to changes in the environment so that the microstructure of the membrane will have more efficient performances and broader application prospects than the current traditional nanofiltration membranes. Herein, the preparation methods of stimuli‐responsive membranes are described and they are systematically classified accordingly to their mechanisms. Moreover, the latest progress of stimuli‐responsive membranes in nanofiltration and the main mechanism of each stimuli‐response type through relevant examples are discussed and summarized. Finally, this review provides new insights into the remaining challenges and future directions of stimuli‐responsive membranes. Fueled by advances in chemistry and materials science, it is expected to build a smart and efficient nanofiltration membrane platform for the benefit of mankind.
Recent advances in stimuli‐responsive smart membranes for nanofiltration, include pH‐responsive, thermo‐responsive, light‐responsive, and electro‐responsive. This review provides a comprehensive discussion on the advancement of stimuli‐responsive membranes with different separation mechanisms. The emergent opportunities, prospects, and challenges on future stimuli‐responsive smart membranes for nanofiltration field are also proposed.
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Understanding the mechanisms of protein interactions with solid surfaces is critical to predict how proteins affect the performance of materials in biological environments. ...Low-fouling and ultra-low fouling surfaces are often evaluated in short-term protein adsorption experiments, where ‘short-term’ is defined as the time required to reach an initial apparent or pseudo-equilibrium, which is usually less than 600 s. However, it has long been recognized that these short-term observations fail to predict protein adsorption behavior in the long-term, characterized by irreversible accumulation of protein on the surface. This important long-term behavior is frequently ignored or attributed to slow changes in surface chemistry over time—such as oxidation—often with little or no experimental evidence. Here, we report experiments measuring protein adsorption on “low-fouling” and “ultralow-fouling” surfaces using single-molecule localization microscopy to directly probe protein adsorption and desorption. The experiments detect protein adsorption for thousands of seconds, enabling direct observation of both short-term (reversible adsorption) and long-term (irreversible adsorption leading to accumulation) protein-surface interactions. By bridging the gap between these two time scales in a single experiment, this work enables us to develop a single mathematical model that predicts behavior in both temporal regimes. The experimental data in combination with the resulting model provide several important insights: (1) short-term measurements of protein adsorption using ensemble-averaging methods may not be sufficient for designing antifouling materials; (2) all investigated surfaces eventually foul when in long-term contact with protein solutions; (3) fouling can occur through surface-induced oligomerization of proteins which may be a distinct step from irreversible adsorption; and (4) surfaces can be designed to reduce oligomerization or the adsorption of oligomers, to prevent or delay fouling.
Polysaccharides offer a wealth of biochemical and biomechanical functionality that can be used to develop new biomaterials. In mammalian tissues, polysaccharides often exhibit a hierarchy of ...structure, which includes assembly at the nanometer length scale. Furthermore, their biochemical function is determined by their nanoscale organization. These biological nanostructures provide the inspiration for developing techniques to tune the assembly of polysaccharides at the nanoscale. These new polysaccharide nanostructures are being used for the stabilization and delivery of drugs, proteins, and genes, the engineering of cells and tissues, and as new platforms on which to study biochemistry. In biological systems polysaccharide nanostructures are assembled via bottom‐up processes. Many biologically derived polysaccharides behave as polyelectrolytes, and their polyelectrolyte nature can be used to tune their bottom‐up assembly. New techniques designed to tune the structure and composition of polysaccharides at the nanoscale are enabling researchers to study in detail the emergent biological properties that arise from the nanoassembly of these important biological macromolecules.
Polysaccharides have many biochemical and biomechanical functions that depend upon their nanoscale structure in their native biological contexts. Here we review recent developments in techniques to tune the assembly of polysaccharides at the nanometer length scale. This body of work is leading to new understanding of the emergent biological properties of polysaccharide nanoassemblies.
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•New surfaces modeling nanostructure and composition of the endothelial glycocalyx.•Characterization by AFM with high-resolution mechanical property mapping.•Glycocalyx ...structure-composition-function relationships.
Blood vessels present a dense, non-uniform, polysaccharide-rich layer, called the endothelial glycocalyx. The polysaccharides in the glycocalyx include polyanionic glycosaminoglycans (GAGs). This polysaccharide-rich surface has excellent and unique blood compatibility. We report new methods for preparing and characterizing dense GAG surfaces that can serve as models of the vascular endothelial glycocalyx. The GAG-rich surfaces are prepared by adsorbing heparin or chondroitin sulfate-containing polyelectrolyte complex nanoparticles (PCNs) to chitosan-hyaluronan polyelectrolyte multilayers (PEMs). The surfaces are characterized by PeakForce tapping atomic force microscopy, both in air and in aqueous pH 7.4 buffer, and by PeakForce quantitative nanomechanics (PF-QNM) mode with high spatial resolution. These new surfaces provide access to heparin-rich or chondroitin sulfate-rich coatings that mimic both composition and nanoscale structural features of the vascular endothelial glycocalyx.
The development of blood-compatible materials represents a grand challenge in biomaterials science. Blood is a complex fluid containing many types of living cells, functional proteins, and other ...signaling molecules, which work together to protect the circulatory system from injury, pathogens, and foreign materials. Blood-contacting biomaterials include the components of cardiovascular implants (such as stents, shunts, and valves) and extracorporeal circuit components (such as tubing, membranes, and pumps). The engineered materials used in these applications are distinctly unlike the biological tissues that make up the cardiovascular system in their physical, chemical, and biological properties, leading to undesirable—and sometimes catastrophic—blood-material interactions. The pursuit of blood-compatible materials challenges nearly every aspect of materials design, including composition, mechanical properties, structure across multiple length scales, tribology, surface physical-chemistry, and biochemical functionalization. Materials have been designed to bind or reject specific blood proteins, interact favorably with specific cell types, or to interact with particular biochemical pathways in blood. This review summarizes the important blood-material interactions that regulate blood compatibility, organizes recent developments in this field from a materials perspective, and recommends areas for future research.
In the past few decades, due to the rapid development of industry and the rapid growth of population, emissions of pollutants to the environment have increased dramatically, and the demand for ...drinking water is also increasing. Water treatment is a matter of concern because it is directly related to the health of humans and wildlife. Graphene and its derivatives have potential applications in seawater desalination and wastewater treatment due to their unique pore structure and ionic molecular sieving separation capabilities. Graphene, graphene oxide (GO), and reduced graphene oxide (rGO) can be formulated into nanoporous materials and composites with tunable properties that can be optimized for water filtration. Methods for perforating graphene include ion etching/ion bombardment and electron beam nanometer engraving, which are briefly introduced in this paper. Graphene-based composites further expand the capabilities of graphene in seawater desalination and wastewater treatment, by introducing new features and properties. In this review, the performance improvement of graphene-based separation membranes in decontamination and desalination in recent years is reviewed in detail. This review focuses on improving the performance of graphene-based membranes for separation, decontamination, and seawater desalination applications, by discussing how various modifications and preparation methods impact important performance properties, including water permeance, selectivity, rejection of solutes, membrane mechanical strength, and antifouling characteristics. We also discuss the outlook for future development of graphene-based membranes.
The formation of polyelectrolyte complex nanoparticles (PCN) was investigated at different charge mixing ratios for the chitosan-heparin (chi-hep) and chitosan-hyaluronan (chi-ha) ...polycation-polyanion pairs. The range of 0.08−19.2 for charge mixing ratio (n +/n −) was examined. The one-shot addition of polycation and polyanion solutions used for the formation of the PCN permitted formation of both cationic and anionic particles from both polysaccharide pairs. The influence of the charge mixing ratio on the size and zeta potential of the particles was investigated. The morphology and stability of the particles when adsorbed to surfaces was studied by scanning electron microscopy (SEM). For most conditions studied, colloidally stable, nonstoichiometric PCN were formed in solution. However, PCN formation was inhibited by flocculation at charge mixing ratios near 1. When adsorbed to surfaces and dried, some formulations resulted in discrete nanoparticles, while others partially or completely aggregated or coalesced, leading to different surface morphologies.
Anomalous protein kinetics on low-fouling surfaces Hedayati, Mohammadhasan; Kipper, Matt J; Krapf, Diego
Physical chemistry chemical physics : PCCP,
2020-Mar-04, Letnik:
22, Številka:
9
Journal Article
Recenzirano
Odprti dostop
In this work, protein-surface interactions were probed in terms of adsorption and desorption of a model protein, bovine serum albumin, on a low-fouling surface with single-molecule localization ...microscopy. Single-molecule experiments enable precise determination of both adsorption and desorption rates. Strikingly the experimental data show anomalous desorption kinetics, evident as a surface dwell time that exhibits a power-law distribution, i.e. a heavy-tailed rather than the expected exponential distribution. As a direct consequence of this heavy-tailed distribution, the average desorption rate depends upon the time scale of the experiment and the protein surface concentration does not reach equilibrium. Further analysis reveals that the observed anomalous desorption emerges due to the reversible formation of a small fraction of soluble protein multimers (small oligomers), such that each one desorbs from the surface with a different rate. The overall kinetics can be described by a series of elementary reactions, yielding simple scaling relations that predict experimental observations. This work reveals a mechanistic origin for anomalous desorption kinetics that can be employed to interpret observations where low-protein fouling surfaces eventually foul when in long-term contact with protein solutions. The work also provides new insights that can be used to define design principles for non-fouling surfaces and to predict their performance.
Ultralow protein fouling behavior is a common target for new high-performance materials. Ultralow fouling is often defined based on the amount of irreversibly adsorbed protein (< 5 ng cm−2) measured ...by a surface ensemble averaging method. However, protein adsorption at solid interfaces is a dynamic process involving multiple steps, which may include adsorption, desorption, and irreversible protein denaturation. In order to better optimize the performance of antifouling surfaces, it is imperative to fully understand how proteins interact with surfaces, including kinetics of adsorption and desorption, conformation, stability, and amount of adsorbed proteins. Defining ultralow fouling surfaces based on a measurement at or near the limit of detection of a surface-averaged measurement may not capture all of this behavior. Single-molecule microscopy techniques can resolve individual protein-surface interactions with high temporal and spatial resolution. This information can be used to tune the properties of surfaces to better resist protein adsorption. In this work, we demonstrate how combining surface plasmon resonance, X-ray photoelectron spectroscopy, atomic force microscopy, and single-molecule localization microscopy provides a more complete picture of protein adsorption on low fouling and ultralow fouling polyelectrolyte multilayer and polymer brush surfaces, over different regimes of protein concentration. In this case, comparing the surfaces using surface plasmon resonance alone is insufficient to rank their resistance to protein adsorption. Our results suggest a revision of the accepted definition of ultralow fouling surfaces is timely: with the advent of time-resolved studies of protein adsorption kinetics at the single-molecule level, it is neither necessary nor sufficient to rely on a surface averaging techniques to qualify ultralow fouling surfaces. Since protein adsorption is a dynamic process, understanding how surface properties affect the kinetics of protein adsorption will enable the design of future generations of advanced antifouling materials.
The design of ultralow fouling surfaces is often optimized based on a single surface-averaging technique measuring the amount of irreversibly adsorbed protein. This work provides a critical comparison of alternative techniques for evaluating protein adsorption on low fouling and ultralow fouling surfaces, and demonstrates how additional information about the dynamics of protein-surface interactions at the interface can be obtained by application of single-molecule microscopy. This approach could be used to better elucidate mechanisms of protein resistance and design principles for advanced ultralow fouling materials.
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