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Showing papers in "Langmuir in 2019"


Journal ArticleDOI
18 Apr 2019-Langmuir
TL;DR: An overview of the state-of-the-art, recent developments as well as emerging trends in the field of nano- and microgels is provided.
Abstract: Nanogels and microgels are soft, deformable, and penetrable objects with an internal gel-like structure that is swollen by the dispersing solvent. Their softness and the potential to respond to external stimuli like temperature, pressure, pH, ionic strength, and different analytes make them interesting as soft model systems in fundamental research as well as for a broad range of applications, in particular in the field of biological applications. Recent tremendous developments in their synthesis open access to systems with complex architectures and compositions allowing for tailoring microgels with specific properties. At the same time state-of-the-art theoretical and simulation approaches offer deeper understanding of the behavior and structure of nano- and microgels under external influences and confinement at interfaces or at high volume fractions. Developments in the experimental analysis of nano- and microgels have become particularly important for structural investigations covering a broad range of length scales relevant to the internal structure, the overall size and shape, and interparticle interactions in concentrated samples. Here we provide an overview of the state-of-the-art, recent developments as well as emerging trends in the field of nano- and microgels. The following aspects build the focus of our discussion: tailoring (multi)functionality through synthesis; the role in biological and biomedical applications; the structure and properties as a model system, e.g., for densely packed arrangements in bulk and at interfaces; as well as the theory and computer simulation.

354 citations


Journal ArticleDOI
26 Mar 2019-Langmuir
TL;DR: The Langmuir adsorption model captures the key physics of molecular interactions at interfaces and laid the foundation for further progress in understanding interfacial phenomena, developing new adsorbent materials, and designing engineering processes.
Abstract: The 100th anniversary of Langmuir’s theory of adsorption is a significant landmark for the physical chemistry and chemical engineering communities. Despite its simplicity, the Langmuir adsorption model captures the key physics of molecular interactions at interfaces and laid the foundation for further progress in understanding interfacial phenomena, developing new adsorbent materials, and designing engineering processes. The Langmuir model has had an exceptional impact on diverse fields within the chemical sciences (ranging from chemical biology to materials science), an impact that became clearer with the development of modified adsorption theories and continues to be relevant today.

199 citations


Journal ArticleDOI
20 Mar 2019-Langmuir
TL;DR: The flexible, highly sensitive, and simply designed NFC/CNT humidity sensor is a promising candidate for various applications in the field of humidity measurement.
Abstract: Flexible and highly sensitive humidity sensors are crucial for humidity detection. In this study, a flexible cellulose nanofiber/carbon nanotube (NFC/CNT) humidity sensor with high sensitivity perf...

160 citations


Journal ArticleDOI
19 Mar 2019-Langmuir
TL;DR: The classical theories as well as recent advancements in this field are summarized and an outlook on future research topics are provided.
Abstract: Electrochemical gas evolution reactions are of vital importance in numerous electrochemical processes including water splitting, chloralkaline process, and fuel cells. During gas evolution reactions, gas bubbles are vigorously and constantly forming and influencing these processes. In the past few decades, extensive studies have been performed to understand the evolution of gas bubbles, elucidate the mechanisms of how gas bubbles impact gas evolution reactions, and exploit new bubble-based strategies to improve the efficiency of gas evolution reactions. In this feature article, we summarize the classical theories as well as recent advancements in this field and provide an outlook on future research topics.

147 citations


Journal ArticleDOI
03 Jun 2019-Langmuir
TL;DR: A facile method for preparing durable superhydrophobic and highly oleophobic surfaces using two kinds of nanoparticles using Epoxy resin and ZnO nanoparticles and SiO2 nanoparticles is demonstrated.
Abstract: Functional surfaces with superhydrophobic and superoleophobic properties are of great interest in many applications. However, such surfaces are generally difficult to obtain. Although a few superamphiphobic surfaces have been developed recently, a challenge still remains in preparing such a surface with good durability which is a critical issue in practical application. In this study, we demonstrate a facile method for preparing durable superhydrophobic and highly oleophobic surfaces using two kinds of nanoparticles. Epoxy resin is used as the adhesive material to improve the wear resistance of the surfaces. ZnO nanoparticles and SiO2 nanoparticles are used to create high surface roughness. The prepared surfaces exhibit excellent superhydrophobicity and high oleophobicity once the nanoparticles are treated with 1 H,1 H,2 H,2 H-perfluorodecyltriethoxydsilane (FAS-17). Water and ethylene glycol contact angles of the coatings can reach up to 172 ? 2? and 157 ? 2?, respectively. After undergoing strong adhesive tape peeling and mechanical abrasion, the coatings still maintain good amphiphobicity.

139 citations


Journal ArticleDOI
06 Aug 2019-Langmuir
TL;DR: This review aims at connecting the knowledge gained from fundamental microbubble studies to the therapeutic efficacy seen in in vitro and in vivo studies, with an emphasis on a better understanding of the response of a microbubbles upon exposure to ultrasound and its interaction with cells and tissues.
Abstract: In the last couple of decades, ultrasound-driven microbubbles have proven excellent candidates for local drug delivery applications. Besides being useful drug carriers, microbubbles have demonstrated the ability to enhance cell and tissue permeability and, as a consequence, drug uptake herein. Notwithstanding the large amount of evidence for their therapeutic efficacy, open issues remain. Because of the vast number of ultrasound- and microbubble-related parameters that can be altered and the variability in different models, the translation from basic research to (pre)clinical studies has been hindered. This review aims at connecting the knowledge gained from fundamental microbubble studies to the therapeutic efficacy seen in in vitro and in vivo studies, with an emphasis on a better understanding of the response of a microbubble upon exposure to ultrasound and its interaction with cells and tissues. More specifically, we address the acoustic settings and microbubble-related parameters (i.e., bubble size a...

118 citations


Journal ArticleDOI
23 Jan 2019-Langmuir
TL;DR: A modified form of Hinze theory was employed to model droplet behavior in analyzed nanoemulsion systems and found that oleic phase appears as uniformly dispersed spherical droplets in 14-6-14 GS-stabilized nanoemulsions, which on PHPA addition changes into a network structure consisting of larger oil droplets.
Abstract: Nanoemulsion systems comprising n-heptane (oleic component), stabilized by the {gemini surfactant (14-6-14 GS) + polymer [partially hydrolyzed poly-acrylamide (PHPA)] + silica (SiO2) nanoparticle} shell and dispersed in aqueous phase, were synthesized by ultrasonication (high-energy method). Influence of ultrasonication time on nanoemulsion kinetics was investigated to predict the saturation droplet diameter. Morphological analysis by transmission electron cryomicroscopy imaging showed that oleic phase appears as uniformly dispersed spherical droplets in 14-6-14 GS-stabilized nanoemulsion, which on PHPA addition changes into a network structure consisting of larger oil droplets. 14-6-14 + PHPA + SiO2 nanoemulsion systems show more effective packing arrangement with irregular-shaped (nonspherical) droplets. Dynamic light scattering studies identified droplet size distribution profiles in the range 4.2-25.4 nm for the surfactant-stabilized nanoemulsion, 125.9-358.8 nm for the surfactant-polymer nanoemulsion, and 88.4-222.3 nm for the surfactant-polymer-nanoparticle-based nanoemulsion in optimal dosage(s). Statistical analyses were performed using normal, log-normal, and Cauchy-Lorentz distribution functions. A modified form of Hinze theory was employed to model droplet behavior in analyzed nanoemulsion systems. Zeta potential values of nanoemulsions were studied at different time intervals to determine kinetic stability as well as corroborate Hinze model findings. In summary, this article aims at investigating nanoemulsion droplet stability by thorough examination of electrostatic repulsive barrier and steric hindrance effects.

112 citations


Journal ArticleDOI
05 Feb 2019-Langmuir
TL;DR: In this review, blood compatibility of a polymer having a PC group is introduced in relation to its hydration structure, followed by a description of the applications of this polymer to cardiovascular medical devices.
Abstract: For the acquisition of blood-compatible materials, various hydrophilic polymers for surface modification have been examined. Among them, polymers with a representative phospholipid polar group, the phosphorylcholine (PC) group, are a successful example. These polymers were designed from inspiration of the cell membrane surface and provide protein adsorption resistance even following contact with plasma. This important property is based on the unique hydration state of water molecules surrounding hydrated polymer; in other words, water molecules weakly interact with the polymers and maintain their favorable cluster structure through hydrogen bonding. These polymers are not only hydrophilic, but also electrically neutral, important characteristics which make hydrogen bonding with water molecules less likely to occur and avoid hydrophobic interactions. Phosphorylcholine groups and other zwitterionic structures are significant as hydrophilic functional groups meeting these important requirements. In this review, blood compatibility of a polymer having a PC group is introduced in relation to its hydration structure, followed by a description of the applications of this polymer to cardiovascular medical devices.

108 citations


Journal ArticleDOI
22 Jan 2019-Langmuir
TL;DR: The surface chemistry and adsorption behavior of submicrometer cellulosic and lignin particles have drawn wide-ranging interest in the scientific community as mentioned in this paper, and they can be used alone, as dual components, or in combination with amphiphilic molecules.
Abstract: The surface chemistry and adsorption behavior of submicrometer cellulosic and lignin particles have drawn wide-ranging interest in the scientific community. Here, we introduce their assembly at fluid/fluid interfaces in Pickering systems and discuss their role in reducing the oil/water interfacial tension, limiting flocculation and coalescence, and endowing given functional properties. We discuss the stabilization of multiphase systems by cellulosic and lignin colloids and the opportunities for their adoption. They can be used alone, as dual components, or in combination with amphiphilic molecules for the design of multiphase systems relevant to household products, paints, coatings, pharmaceutical, foodstuff, and cosmetic formulations. This invited feature article summarizes some of our work and that of colleagues to introduce the readers to this fascinating and topical area.

107 citations


Journal ArticleDOI
12 Mar 2019-Langmuir
TL;DR: Research efforts related to Langmuir nanoarchitectonics are summarized including the basics for anomalies in molecular interactions such as highly enhanced molecular recognition capabilities and the fabrication of supramolecular receptors and two-dimensional patterns.
Abstract: Methodology to combine nanotechnology and these organization processes has been proposed as a novel concept of nanoarchitectonics, which can fabricate functional materials with nanolevel units. As an instant nanoarchitectonics approach, confining systems within a two-dimensional plane to drastically reduce translational motion freedom can be regarded as one of the rational approaches. Supramolecular chemistry and nanofabrication and their related functions at the air–water interface with the concept of nanoarchitectonics would lead to the creation of a novel methodology of Langmuir nanoarchitectonics. In this feature article, we briefly summarize research efforts related to Langmuir nanoarchitectonics including the basics for anomalies in molecular interactions such as highly enhanced molecular recognition capabilities. It is also extended to frontiers including the fabrication of supramolecular receptors and two-dimensional patterns with subnanometer-scale structural regulation, manual control of molecul...

102 citations


Journal ArticleDOI
22 Jul 2019-Langmuir
TL;DR: The aim of this feature article is to bring together recent achievements with designer PAs with respect to their self-assembly processes and applications and provide a conceptual demonstration of the different approaches taken towards the construction of these task-specific PAs.
Abstract: Peptide amphiphiles (PAs) are extremely attractive as molecular building blocks, especially in the bottom-up fabrication of supramolecular soft materials, and have potential in many important applications across various fields of science and technology. In recent years, we have designed and synthesized a large group of peptide amphiphiles. This library of PAs has the ability to self-assemble into a variety of aggregates such as fibers, nanosphere, vesicles, nanosheet, nanocups, nanorings, hydrogels, and so on. The mechanism behind the formation of such a wide range of structures is intriguing. Each system has its individual method of aggregation and results in assemblies with important applications in areas including chemistry, biology, and materials science. The aim of this feature article is to bring together our recent achievements with designer PAs with respect to their self-assembly processes and applications. Emphasis is placed on rational design, mechanistic aspects of the self-assembly processes, and the applications of these PAs. We hope that this article will provide a conceptual demonstration of the different approaches taken toward the construction of these task-specific PAs.

Journal ArticleDOI
31 Jan 2019-Langmuir
TL;DR: The potential of earth-abundant MXene family materials to construct low-cost and high-performance electrocatalysts for the oxygen reduction reaction (ORR) is demonstrated, with a positive shift in both onset and peak potentials toward ORR.
Abstract: One of the major challenges associated with fuel cells is exploring highly efficient and low-cost electrocatalysts for the oxygen reduction reaction (ORR). Herein, the feasibility of using Ti3C2 MXene nanoparticles (NPs) to enhance the electrocatalytic activity of g-C3N4 for ORR was investigated. By varying the content of Ti3C2 NPs, a series of g-C3N4/Ti3C2 heterostructures were obtained, displaying enhanced electrocatalytic activity, including a positive shift in both onset and peak potentials toward ORR, compared to the original g-C3N4 in basic solution. We attribute the improvement to the favorable electrical conductivity of well-dispersed Ti3C2 MXene nanoparticles and also enhanced O2 adsorption due to the electronic coupling effect between g-C3N4 and Ti3C2 in the heterostructures. This work demonstrates the potential of earth-abundant MXene family materials to construct low-cost and high-performance electrocatalysts.

Journal ArticleDOI
20 Aug 2019-Langmuir
TL;DR: This feature article reviews both natural and artificial hierarchical surface structures and their function in repelling liquids and draws some general conclusions as a guideline for designing robust superhydrophobic and superoleophobic surfaces.
Abstract: Many surfaces possessing robust super liquid repellency are hierarchically structured on the nano- and micrometer scales. Several examples are found in nature, such as the self-cleaning leaves of lotus plants and anisotropic, water-guiding rice leaves. Each surface design has unique properties optimized for specific wetting conditions. In this invited feature article, we review both natural and artificial hierarchical surface structures and their function in repelling liquids. We discuss different types of structures needed in various wetting situations and draw some general conclusions as a guideline for designing robust superhydrophobic and superoleophobic surfaces.

Journal ArticleDOI
24 May 2019-Langmuir
TL;DR: Comprehensive analysis confirms that UV-induced cross-linking is an effective technique to suppress the crystallinity of the polymer matrix and reduce ion aggregation, yielding improved Li+ transport number and ionic conductivity at ambient temperature, by tailoring the structural/morphological characteristics ofThe polymer matrix.
Abstract: We report a thorough, multitechnique investigation of the structure and transport properties of a UV-cross-linked polymer electrolyte based on poly(ethylene oxide), tetra(ethylene glycol)dimethyl ether (G4), and lithium bis(trifluoromethane)sulfonimide. The properties of the cross-linked polymer electrolyte are compared to those of a non-cross-linked sample of same composition. The effect of UV-induced cross-linking on the physico/chemical characteristics is evaluated by X-ray diffraction, differential scanning calorimetry, shear rheology, 1H and 7Li magic angle spinning nuclear magnetic resonance (NMR) spectroscopy, 19F and 7Li pulsed field gradient stimulated echo NMR analyses, electrochemical impedance spectroscopy, and Fourier transform Raman spectroscopy. Comprehensive analysis confirms that UV-induced cross-linking is an effective technique to suppress the crystallinity of the polymer matrix and reduce ion aggregation, yielding improved Li+ transport number (>0.5) and ionic conductivity (>0.1 mS cm?1) at ambient temperature, by tailoring the structural/morphological characteristics of the polymer matrix. Finally, the polymer electrolyte allows reversible operation with stable profile for hundreds of cycles upon galvanostatic test at ambient temperature of LiFePO4-based lithium-metal cells, which deliver full capacity at 0.05 or 0.1C current rate and keep high rate capabilities up to 1C. This enforces the role of UV-induced cross-linking in achieving excellent electrochemical characteristics, exploiting a practical, easy up-scalable process.

Journal ArticleDOI
05 Feb 2019-Langmuir
TL;DR: Key structural variables are identified, consider their influence on essential properties such as overall hydrophilicity and long-term stability, and discuss promising targets for the synthesis of new variants of zwitterionic polymers.
Abstract: The widespread occurrence of zwitterionic compounds in nature has incited their frequent use in designing biomimetic materials. Therefore, zwitterionic polymers are a thriving field. A particular interest for this particular polymer class has currently focused on their use in establishing neutral, low-fouling surfaces. After highlighting strategies to prepare model zwitterionic surfaces as well as those that are more suitable for practical purposes relying strongly on radical polymerization methods, we present recent efforts to diversify the structure of the hitherto quite limited variety of zwitterionic monomers and of the derived polymers. We identify key structural variables, consider their influence on essential properties such as overall hydrophilicity and long-term stability, and discuss promising targets for the synthesis of new variants.

Journal ArticleDOI
08 Jan 2019-Langmuir
TL;DR: This Feature Article focuses on recent advances in the bioconjugation of surface-bound zwitterionic polymers for biospecific antifouling surfaces as well as chain-end and side-chain functionalization.
Abstract: This Feature Article focuses on recent advances in the bioconjugation of surface-bound zwitterionic polymers for biospecific antifouling surfaces. Various approaches for the functionalization of antifouling zwitterionic polymers are systematically investigated, such as chain-end and side-chain functionalization. Side-chain functionalization methods can be further classified as those that are achieved through homopolymerization of custom-synthesized zwitterionic monomers equipped with reactive groups, or those that are achieved via synthesis of random or block copolymers combining different monomers with antifouling functionality and others with reactive groups. Several of the pros and cons of these approaches are outlined and discussed. Finally, some perspective and future directions of research are presented toward long-term stable, generically repelling surfaces that strongly and specifically adhere to a single component in a complex mixture.

Journal ArticleDOI
19 Mar 2019-Langmuir
TL;DR: This approach shows how Cassie-Baxter, Wenzel, hemiwicking, and other equations for rough, textured or complex geometry surfaces and for electrowetting and dielectrowetting can be used with the Young's law contact angle replaced by the apparent contact angle from the equivalent smooth lubricant-impregnated surface.
Abstract: A fundamental limitation of liquids on many surfaces is their contact line pinning. This limitation can be overcome by infusing a nonvolatile and immiscible liquid or lubricant into the texture or roughness created in or applied onto the solid substrate so that the liquid of interest no longer directly contacts the underlying surface. Such slippery liquid-infused porous surfaces (SLIPS), also known as lubricant-impregnated surfaces, completely remove contact line pinning and contact angle hysteresis. However, although a sessile droplet may rest on such a surface, its contact angle can be only an apparent contact angle because its contact is now with a second liquid and not a solid. Close to the solid, the droplet has a wetting ridge with a force balance of the liquid-liquid and liquid-vapor interfacial tensions described by Neumann's triangle rather than Young's law. Here, we show how, provided the lubricant coating is thin and the wetting ridge is small, a surface free energy approach can be used to obtain an apparent contact angle equation analogous to Young's law using interfacial tensions for the lubricant-vapor and liquid-lubricant and an effective interfacial tension for the combined liquid-lubricant-vapor interfaces. This effective interfacial tension is the sum of the liquid-lubricant and the lubricant-vapor interfacial tensions or the liquid-vapor interfacial tension for a positive and negative spreading power of the lubricant on the liquid, respectively. Using this approach, we then show how Cassie-Baxter, Wenzel, hemiwicking, and other equations for rough, textured or complex geometry surfaces and for electrowetting and dielectrowetting can be used with the Young's law contact angle replaced by the apparent contact angle from the equivalent smooth lubricant-impregnated surface. The resulting equations are consistent with the literature data. These results enable equilibrium contact angle theory for sessile droplets on surfaces to be used widely for surfaces that retain a thin and conformal SLIPS coating.

Journal ArticleDOI
14 Jan 2019-Langmuir
TL;DR: A novel self-cleaning mechanism of textured surfaces attributed to a spontaneous coalescence-induced wetting transition is demonstrated, which can explain why droplets on rough surfaces are able to change from the highly adhesive Wenzel state to the low adhesion Cassie-Baxter state and achieve self- Cleaning.
Abstract: The superhydrophobic leaves of a lotus plant and other natural surfaces with self-cleaning function have been studied intensively for the development of artificial biomimetic surfaces. The surface roughness generated by hierarchical structures is a crucial property required for superhydrophobicity and self-cleaning. Here, we demonstrate a novel self-cleaning mechanism of textured surfaces attributed to a spontaneous coalescence-induced wetting transition. We focus on the wetting transition as it represents a new mechanism, which can explain why droplets on rough surfaces are able to change from the highly adhesive Wenzel state to the low adhesion Cassie–Baxter state and achieve self-cleaning. In particular, we perform many-body dissipative particle dynamics simulations of liquid droplets (with a diameter of 89 μm) sitting on mechanically textured substrates. We quantitatively investigate the wetting behavior of an isolated droplet as well as coalescence of droplets for both Cassie–Baxter and Wenzel states...

Journal ArticleDOI
31 Jul 2019-Langmuir
TL;DR: This work proposed and synthesized a new type of upconversion nanoparticles@carbon dots@meso-SiO2 nanohybrids by integrating two fluorescent materials of lanthanide-doped NaYF4 upconverted nanoparticles and carbon dots into mesoporous silica to produce a novel sandwich-like core-shell structure and a dual-mode fluorescence from UCNPs and CDs.
Abstract: Development of advanced fluorescent materials for constructing a secure and unclonable encryption is urgently required; however, their application in anti-counterfeiting applications is a great challenge. In this work, we proposed and synthesized a new type of upconversion nanoparticles@carbon dots@meso-SiO2 nanohybrids by integrating two fluorescent materials of lanthanide-doped NaYF4 upconversion nanoparticles (UCNPs) and carbon dots (CDs) into mesoporous silica (mSiO2) to produce a novel sandwichlike core-shell structure and a dual-mode fluorescence from UCNPs and CDs. By tailoring the UCNP core of different upconversion luminescence, all three kinds of dual-mode luminescent UCNPs@CDs@mSiO2 nanohybrids exhibited typical RGB upconversion luminescence under a 980 nm laser and blue downconversion luminescence under a 365 nm UV light. Due to strong the hydrophilic nature of the nanohybrids, they can be further fabricated into environmentally benign luminescent inks for creating highly secured, fluorescent-based, three-dimensional anti-counterfeiting barcodes via inkjet printing. The resultant UCNPs@CDs@mSiO2 inks with a dual-mode and tunable luminescence nature endow the inkjet-printing barcodes with an extremely high encoding capacity and high security. Such dual-mode fluorescent inks and barcodes are simple to fabricate, easy to view, efficient for coding, and difficult to clone, thus making them promising nanomaterials for anti-counterfeiting applications.

Journal ArticleDOI
25 Jan 2019-Langmuir
TL;DR: A self-assembly of clay nanotubes in functional arrays for the production of organized organic/inorganic heterostructures is described, and core-shell mesocatalysts are based on a safe and cheap natural clay nanomaterial and may be scaled up for industrial applications.
Abstract: A self-assembly of clay nanotubes in functional arrays for the production of organized organic/inorganic heterostructures is described. These 50-nm-diameter natural alumosilicate nanotubes are biocompatible. Halloysite allows for 10-20 wt % chemical/drug loading into the inner lumen, and it gives an extended release for days and months (anticorrosion, self-healing, flame-retardant, antifouling, and antibacterial composites). The structured surfaces of the oriented nanotube micropatterns enhance interactions with biological cells, improving their capture and inducing differentiation in stem cells. An encapsulation of the cells with halloysite enables control of their growth and proliferation. This approach was also developed for spill petroleum bioremediation as a synergistic process with Pickering oil emulsification. We produced 2-5-nm-diameter particles (Au, Ag, Pt, Co, Ru, Cu-Ni, Fe3O4, ZrO2, and CdS) selectively inside or outside the aluminosilicate clay nanotubes. The catalytic hydrogenation of benzene and phenol, hydrogen production, impacts of the metal core-shell architecture, the metal particle size, and the seeding density were optimized for high-efficiency processes, exceeding the competitive industrial formulations. These core-shell mesocatalysts are based on a safe and cheap natural clay nanomaterial and may be scaled up for industrial applications.

Journal ArticleDOI
30 Apr 2019-Langmuir
TL;DR: This work focuses on a specific class of gelator, the functionalized dipeptide, and discusses the current state of the art in the area, focusing on how these materials can be controlled.
Abstract: Low-molecular-weight gels are formed by the self-assembly of small molecules into fibrous networks that can immobilize a significant amount of solvent. Here, we focus on our work with a specific class of gelator, the functionalized dipeptide. We discuss the current state of the art in the area, focusing on how these materials can be controlled. We also highlight interesting and unusual observations and unanswered questions in the field.

Journal ArticleDOI
11 Jun 2019-Langmuir
TL;DR: Collectively, studies in the literature demonstrate the great potential of using trehalose as the sole CPA for cell banking, to facilitate the widespread use of living cells in modern medicine.
Abstract: Advances in stem cell technology and regenerative medicine have underscored the need for effective banking of living cells. Cryopreservation, using very low temperatures to achieve suspended animation, is widely used to store or bank cells for later use. This process requires the use of cryoprotective agents (CPAs) to protect cells against damage caused by the cooling and warming process. However, current popular CPAs like DMSO can be toxic to cells and must be thoroughly removed from cells before they can be used for research or clinical applications. Trehalose, a nontoxic sugar found in organisms capable of withstanding extreme cold or desiccation, has been explored as an alternative CPA. The disaccharide must be present on both sides of the cellular membrane to provide cryo-protection. However, trehalose is not synthesized by mammalian cells nor has the capability to diffuse through their plasma membranes. Therefore, it is crucial to achieve intracellular delivery of trehalose for utilizing the full potential of the sugar for cell banking. In this review, various methods that have been explored to deliver trehalose into mammalian cells for their banking at both cryogenic and ambient temperatures are surveyed. Among them, the nanoparticle-mediated approach is particularly exciting. Collectively, studies in the literature demonstrate the great potential of using trehalose as the sole CPA for cell banking, to facilitate the widespread use of living cells in modern medicine.

Journal ArticleDOI
05 Feb 2019-Langmuir
TL;DR: The PSBMA-NaSS hydrogels collapsed when the ionic strength increased because the ions can weaken the repulsive interaction of the anionic groups of PNaSS, and showed high adsorption of methylene blue.
Abstract: In this work, we studied the swelling behavior and adsorption behavior of zwitterionic copolymer hydrogels, which were prepared via the free radical copolymerization of sulfobetaine methacrylate (SBMA) and other monomers including sodium p-styrenesulfonate (NaSS), acrylic acid, N-isopropylacrylamide, and 2-(dimethylamino) ethyl methacrylate. The PSBMA hydrogel showed increased swelling ratio with the increase of ionic strength at the same temperature, and the swelling process reflected endothermicity. Interestingly, the PSBMA-NaSS hydrogels collapsed when the ionic strength increased because the ions can weaken the repulsive interaction of the anionic groups of PNaSS. In addition, the PSBMA-NaSS showed high adsorption of methylene blue (760 mg/g). The zwitterionic hydrogels have potential to be used as an adsorbent in the field of wastewater treatment.

Journal ArticleDOI
22 Oct 2019-Langmuir
TL;DR: P pH-responsive liquid crystalline lipid nanoparticles, which are dual loaded by Brucea javanica oil and doxorubicin hydrochloride and display a pH-induced inverted hexagonal to cubic to emulsified microemulsion phase transition, demonstrated enhanced anti-tumor efficacy and highlighted the necessity of further understanding of the link between the established pH-dependent drug release profiles of the nanocarriers.
Abstract: We report pH-responsive liquid crystalline lipid nanoparticles, which are dual-loaded by Brucea javanica oil (BJO) and doxorubicin hydrochloride (DOX) and display a pH-induced inverted hexagonal (pH = 7.4) to cubic (pH = 6.8) to emulsified microemulsion (pH = 5.3) phase transition with a therapeutic application in cancer inhibition. BJO is a traditional herbal medicine that strongly inhibits the proliferation and metastasis of various cancers. Doxorubicin is an antitumor drug, which prevents DNA replication and hampers protein synthesis through intercalation between the base pairs of the DNA helices. Its dose-dependent cardiotoxicity imposes the need for safe delivery carriers. Here, pH-induced changes in the structural and interfacial properties of designed multicomponent drug delivery (monoolein-oleic acid-BJO-DOX) systems are determined by synchrotron small-angle X-ray scattering and the Langmuir film balance technique. The nanocarrier assemblies display good physical stability in the studied pH range and adequate particle sizes and ζ-potentials. Their interaction with model lipid membrane interfaces is enhanced under acidic pH conditions, which mimic the microenvironment around tumor cells. In vitro cytotoxicity and apoptosis studies with BJO-DOX dual-loaded pH-switchable liquid crystalline nanoparticles are performed on the human breast cancer Michigan Cancer Foundation-7 (MCF-7) cell line and MCF-7 cells with doxorubicin resistance (MCF-7/DOX), respectively. The obtained pH-sensitive nanomedicines exhibit enhanced antitumor efficacy. The performed preliminary studies suggest a potential reversal of the resistance of the MCF-7/DOX cells to DOX. These results highlight the necessity for further understanding the link between the established pH-dependent drug release profiles of the nanocarriers and the role of their pH-switchable inverted hexagonal, bicontinuous cubic, and emulsified microemulsion inner organizations for therapeutic outcomes.

Journal ArticleDOI
05 Feb 2019-Langmuir
TL;DR: Results show that this antifouling hybrid hydrogel as a wound dressing provided a promising strategy for the treatment of diabetic ulcers.
Abstract: Patients with diabetic wounds have deficient local and systemic cellular immunity. Herein, a new silver nanoparticle-containing hydrogel with antifouling properties was developed for enhancing the immune response in diabetic wound healing. The antifouling property was obtained by adjusting the composition of cationic chitosan and anionic dextran to approach zero charge. Furthermore, this hybrid hydrogel showed long-lasting and broad-spectrum antibacterial activity. Rapid wound contraction was observed after the treatment with the hydrogel, which suggested its superior healing activity to promote fibroblast migration, granulation tissue formation, and angiogenesis. The upregulation of CD68+ and CD3+ expression levels demonstrated that the hydrogel could trigger immune responses in the treatment of wound healing. These results show that this antifouling hybrid hydrogel as a wound dressing provided a promising strategy for the treatment of diabetic ulcers.

Journal ArticleDOI
05 Feb 2019-Langmuir
TL;DR: A robust one-step mussel-inspired method to construct a highly chemical stable and excellent antibiofouling membrane surface coating with a highly efficient codeposition of polydopamine (PDA) with zwitterionic polymer is reported.
Abstract: Although abundant works have been developed in mussel-inspired antifouling coatings, most of them suffer from poor chemical stability, especially in a strongly alkaline environment. Herein, we report a robust one-step mussel-inspired method to construct a highly chemical stable and excellent antibiofouling membrane surface coating with a highly efficient codeposition of polydopamine (PDA) with zwitterionic polymer. In the study, PDA and polyethylenimine-quaternized derivative (PEI-S) are codeposited on the surface of poly(ether sulfone) (PES) ultrafiltration membrane in water at room temperature. In contrast to individual PDA coating, the obtained PDA/PEI-S coating exhibits excellent chemical stability even in a strongly alkaline environment owing to the cross-linking and unexpected cation−π interaction between the PEI-S and PDA. Thanks to the introduction of PEI-S, systematic protein adsorption tests and bacteria adhesion experiments demonstrated that the surfaces could prevent bovine serum fibrinogen an...

Journal ArticleDOI
24 Jul 2019-Langmuir
TL;DR: The emulsifying and dispersing mechanisms of oil-in-water emulsions stabilized by 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-oxidized cellulose nanofibers (CNFs) showed that the higher the oil/water interfacial tension, the greater the amount of CNFs adsorbed at theOil/water interface, making the CNF-adsorbed oil-
Abstract: The emulsifying and dispersing mechanisms of oil-in-water emulsions stabilized by 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO)-oxidized cellulose nanofibers (CNFs) have been investigated. The emulsifying mechanism was studied by changing the oil/water interfacial tension from 8.5 to 53.3 mN/m using various types of oils. The results showed that the higher the oil/water interfacial tension, the greater is the amount of CNFs adsorbed at the oil/water interface, making the CNF-adsorbed oil-in-water emulsions thermodynamically more stable. Moreover, the amount of CNFs adsorbed on the surfaces of the oil droplets increased with increasing interfacial area. The dispersion stability of the oil droplets was dominated by the CNF concentration in the water phase. Above the critical concentration (0.15% w/w), the CNFs formed network structures in the water phase, and the emulsion was effectively stabilized against creaming. Emulsion formation and the CNF network structures in the emulsion were visualized by cryo-scanning electron microscopy.

Journal ArticleDOI
20 Jun 2019-Langmuir
TL;DR: The development of CDs is introduced in this feature article but also their applications where surface chemistry plays a critical role are highlighted.
Abstract: Carbon dots (CDs) are a novel class of nanoparticles with excellent properties. The development of CDs involves versatile synthesis, characterization, and various applications. However, the importa...

Journal ArticleDOI
Yanbao Guo, Xuanli Zhou, Deguo Wang, Xiaqing Xu1, Quan Xu 
17 Oct 2019-Langmuir
TL;DR: An increased oxidation and replacement of C by O atoms occurred on MXene at higher temperatures, which has a profound impact on the adhesion and friction between MXene and probe tip.
Abstract: MXene is a new type of two-dimensional (2D) material that finds wide applications; however, its adhesion and tribological properties have not yet been fully revealed. Here, the chemical structure of MXene was revealed by X-ray diffraction, and the adhesion and friction behaviors of MXene were studied with atomic force microscopy (AFM) Nanoman technology. It was found in AFM tests that MXene exhibited enhanced adhesion and friction at higher pressure but exhibited reduced adhesion and friction at elevated temperature, while the sliding speed and delay time of the AFM probe have negligible effects on the friction. X-ray photoelectron spectroscopy was used to reveal the change in the chemical structure of MXene at different temperatures. We found increased oxidation, and replacement of C by O atoms occurred on MXene at higher temperatures, which has a profound impact on the adhesion and friction between MXene and the probe tip. This discovery lays the foundation for understanding the adhesion mechanism and the dynamic adhesion behavior in friction of MXene, rendering MXene a much broader application prospect.

Journal ArticleDOI
05 Feb 2019-Langmuir
TL;DR: The zwitterion-modified membrane is promising as a highly permeable fouling resistant cross-linked polyamide network for various water treatment applications.
Abstract: A simple scalable strategy is proposed to fabricate highly permeable antifouling nanofiltration membranes. Membranes with a selective thin polyamide layer were prepared via interfacial polymerization incorporating building blocks of zwitterionic copolymers. The zwitterionic copolymer, poly(aminopropyldimethylaminoethyl methacrylate)-co-poly(sulfobetaine methacrylate) with an average molecular weight of 6.1 kg mol–1, was synthesized in three steps: (i) polymerization of dimethylaminoethyl methacrylate to yield the base polymer by atom transfer radical polymerization (ATRP), (ii) fractional sulfobetainization via quaternization, and (iii) amination via quaternization. The effect of the zwitterionic polymer content on the polyamide surface characteristics, fouling resistance, and permeance is demonstrated. The zwitterion-modified membrane becomes more hydrophilic with lower surface roughness, as the zwitterionic polymer fraction increases. The excellent fouling resistance of the zwitterion-modified membrane ...