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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. [ABSTRACT FROM AUTHOR]

Abstract: Phospholipid coatings on titanium implants have been shown to enhance osteoblast activity, promote mineralization, and facilitate implant osseointegration in vivo. To date, dip and drip coating techniques have been used to apply these coatings. These coating techniques are easy to perform, but present difficulties in controlling the characteristics of the coating on the final surface, resulting in inconsistent, non-uniform, non-conformal coatings that are too thick for in vivo use. Electrohydrodynamic atomization (electro-spraying or e-spraying) is a versatile and easy method of creating thin, uniform and consistent coatings by atomizing a liquid with electrical forces. e-Spraying provides the advantage of being able to create coatings with relatively high efficiencies, while providing good control of coating morphology, especially on rough and intricately shaped surfaces, which is an important consideration for cell attachment and growth. Other advantages of this technique are low cost and easy setup. The purpose of this study was to develop an e-spraying technique for applying phospholipid coatings on commercially pure titanium implant materials. [Copyright &y& Elsevier]

Abstract: The activation of surfaces by covalent attachment of bioactive moieties is an important strategy for improving the performance of biomedical materials. Such techniques have also been used as tools to study cellular responses to particular chemistries of interest. The creation of gradients of covalently bound chemistries is a logical extension of this technique. Gradient surfaces may permit the rapid screening of a large range of concentrations in a single experiment. In addition, the biological response to the gradient itself may provide new information on receptor requirements and cell signaling. The current work describes a rapid and flexible technique for the covalent addition of bioactive peptide gradients to a surface or gel and a simple fluorescence technique for assaying the gradient. In this technique, bioactive peptides with a terminal cysteine are bound via a heterobifunctional coupling agent to primary amine-containing surfaces and gels. A gradient in the coupling agent is created on the surfaces or gels by varying the residence time of the coupling agent across the surface or gel, thereby controlling the extent of reaction. We demonstrate this technique using poly(l-lysine)-coated glass surfaces and fibrin gels. Once the surface or gel has been activated by the addition of the coupling agent gradient, the bioactive peptide is added. Quantitation of the gradient is achieved by measuring the reaction kinetics of the coupling agent with the surface or gel of interest. This can be done either by fluorescently labeling the coupling agent (in the case of surfaces) or by spectrophotometrically detecting the release of pyridine-2-thione, which is produced when the thiol-reactive portion of the coupling agent reacts. By these methods, we can obtain reasonably precise estimates for the peptide gradients without using expensive spectroscopic or radiolabeling techniques. Validation with changes in fibroblast cell migration behavior across a bioactive peptide gradient illustrates preservation of peptide function as well as the usefulness of this technique. [Copyright &y& Elsevier]

The phase behavior of a biocompatible binary polyanhydride blend system composed of poly[1,6-bis(p-carboxyphenoxy)hexane] (poly(CPH)) and poly(sebacic acid) (poly(SA)) is described. The phase behavior is determined from the CPH-SA segmental interaction parameter, χ, obtained from in situ small angle X-ray scattering (SAXS) experiments. The predicted phase diagram has an upper critical solution temperature (UCST) with a critical point of 114 °C. The phase diagram is validated by optical microscopy (cloud point determination) of blend films. However, the full range of blend compositions is not accessible via cloud point measurements, because the melting point of poly(CPH) is above the critical point. Additionally, the poly(CPH) crystallinity interferes with cloud point determination because the length scale of the amorphous phase separation and that of the crystallinity are both near the limit of resolution of the optical microscope. The poly(CPH)-rich region of the phase diagram was investigated by ex situ atomic force microscopy on thin blend films. Finally, in order to validate the use of molecular simulations to study energetic and structural properties of this system, χ is also computed from molecular dynamics both above and below the critical point. Excellent agreement is obtained for all three experimental methods and the computational technique. The results are compared to a simple group contribution method for computing the solubility parameters of the polymers. This technique fails to accurately predict the phase diagram. [Copyright &y& Elsevier]

A thorough understanding of the factors affecting drug release mechanisms from surface-erodible polymer devices is critical to the design of optimal delivery systems. Poly(sebacic anhydride) (PSA) microspheres were loaded with three model drug compounds (rhodamine B, p-nitroaniline and piroxicam) with a range of polarities (water solubilities). The drug release profiles from monodisperse particles of three different sizes were compared to release from polydisperse microspheres. Each of the model drugs exhibited different release mechanisms. Drug distribution within the polymer was investigated by laser scanning confocal microscopy and scanning electron microscopy. Rhodamine, the most hydrophilic compound investigated, was localized strongly toward the microsphere surface, while the much more hydrophobic compound, piroxicam, distributed more evenly. Furthermore, all three compounds were most uniformly distributed in the smallest microspheres, most likely due to the competing effects of drug diffusion out of the nascent polymer droplets and the precipitation of polymer upon solvent extraction, which effectively “traps” the drug in the polymer matrix. The differing drug distributions were manifested in the drug release profiles. Rhodamine was released very quickly independent of microsphere size. Thus, extended release profiles may not be obtainable if the drug strongly redistributes in the microspheres. The release of p-nitroaniline was more prolonged, but still showed little dependence on microsphere size. Hence, when water-soluble drugs are encapsulated with hydrophobic polymers, it may be difficult to tailor release profiles by controlling microsphere size. The piroxicam-loaded microspheres exhibit the most interesting release profiles, showing that release duration can be increased by decreasing microsphere size, resulting in a more uniform drug distribution. [Copyright &y& Elsevier]

This work investigates the relationship between polymer microstructure and drug release kinetics in the bioerodible polyanhydride system, poly[(1,6-bis-p-carboxyphenoxy hexane)–co-(sebacic anhydride)] (CPH–SA). Model drugs, p-nitroaniline (PNA) and disperse yellow 3 (DY), were selected based on compatibility with CPH and SA, respectively. The polymer microstructure and compatibility of the drug with the constituent monomers were determined to have significant influence over the release kinetics of the drugs studied. Polymer systems with homogeneous microstructure, poly(SA) and 50:50 CPH–SA, showed simultaneous polymer degradation and drug release, although the solubility of the drug in the polymer influenced the shape of the release profiles. For the heterogeneous copolymers, 20:80 and 80:20 CPH–SA, individual monomer release kinetics demonstrated the effects of drug partitioning within a phase-separated microstructure. The PNA molecules partition preferentially into the CPH microdomains in the 20:80 CPH–SA copolymer while the DY molecules partition preferentially into the SA microdomains in the 80:20 CPH–SA copolymer. These studies suggest that the drug release mechanism is driven by polymer microstructure, compatibility of the drug with the constituent polymer phases, and solubility of the drug within the polymer. A thorough understanding of drug–polymer interactions as well as the polymer microstructure will pave the way for more accurate predictions of drug release from bioerodible polyanhydrides. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

In this work, innovative hybrid poly(ethylene terephthalate) (PET) materials with strong luminescence were successfully synthesized by doping PET with silicon‐linked poly(ethylene glycol)‐PET copolymer nanostructures either with (Si‐PEG‐PET) or with (ETP@Si‐PEG‐PET) luminescent Eu3+‐complexes. The chemical properties and nanostructures of the hybrid materials were characterized by Fourier‐transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, x‐ray photoelectron spectroscopy, and high‐resolution transmission electron microscopy. PET composites ranging from 0.25 to 4 wt% silicon additive were prepared by the melt blending method. The crystal properties, mechanical properties, and fluorescence properties of the composites were systematically studied by differential scanning calorimetry, x‐ray diffractometry, tensile testing, and fluorescence spectrometry. When the addition of Si‐PEG‐PET or ETP@Si‐PEG‐PET was 0.75 wt%, the relative crystallinity and maximum tensile strength increase substantially. Moreover, the fluorescence intensity of hybrid luminescent PET materials is the strongest at 0.75 wt% loading. ETP@Si‐PEG‐PET not only endows PET polyester with stronger fluorescence properties and mechanical properties but also acts as an effective nucleation additive for PET. Highlights: Silicon‐linked poly(ethylene glycol)‐poly(ethylene terephthalate) (PEG‐PET) nanostructures generate hybrid luminescent PET materials.ETP@Si‐PEG‐PET improves the crystallization rate and crystallinity of PET.The composite with 0.75% addition showed the best fluorescence performance.Three‐dimensional‐grid structure of ETP@Si‐PEG‐PET enhances the mechanical property of PET. [ABSTRACT FROM AUTHOR]

• Chitosan/alginate and N,N- dimethyl chitosan/alginate-based adsorbents are prepared. • An ionic liquid is used to carry out the polysaccharide-based adsorbents. • Adsorbents are produced by precipitating of blends performed in an ionic liquid. • The ionic liquid is recovered and reused to create new adsorbents. • The adsorbents have high capacity for removing Pb(II) ions from aqueous systems. Alginate/chitosan (ALG/CHT) and alginate/ N , N -dimethyl chitosan (ALG/DMC) polyelectrolyte complex (PEC)-based adsorbents with high capacities for removing Pb(II) from aqueous systems are produced in [1-hydrogen-3-methylimidazolium hydrogen sulfate ionic liquid ([Hmim][HSO 4 ―]). The [Hmim][HSO 4 ―] is recovered, characterized by 1H NMR and reused to yield novel polysaccharide-based adsorbents. As-obtained PEC materials are characterized through infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and Zeta potential measurements. Kinetic and equilibrium adsorption studies reveal that the pseudo-second-order Kinetic, as well as the Redlich-Peterson isotherm, provide the best fits for the experimental data, respectively. CHT/ALG and DMC/ALG adsorbents promoted maximum adsorption capacities (q m) of 529.4 mg g−1 and 560.2 mg g−1, respectively. After adsorption, the materials are characterized by infrared spectroscopy and X-ray photoelectron spectroscopy, confirming that the chemisorption prevails upon Pb(II) removal. Also, PECs produced in the recovered [Hmim][HSO 4 ―] have good capacities for removing Pb(II) ions from aqueous systems as well. This study showed that the [Hmim][HSO 4 ―] is an alternative solvent to prepare novel and eco-friendly PEC-based adsorbents. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Human activities are producing increasing amounts of oily water. Therefore, methods for oil/water separation are attracting great attention. Membranes, including nanofibers for oil/water separation based on superwetting surfaces have advantages of low cost, high efficiency, and environmental friendliness. In addition to the common superhydrophobic and superhydrophilic surfaces, other novel superwetting membranes have been developed for oil/water separation. This review introduces and discusses membranes and nanofibers reported in recent years for oil/water separation, with emphasis on coupling the wettability characteristics with the structural features. We mainly discuss five types of membranes with superwetting surfaces. In each category, representative research, manufacturing technology, membrane structure, and applications are discussed in detail. Finally, the challenges and future opportunities for superwetting membranes in the field of oil/water separation are put forward. [ABSTRACT FROM AUTHOR]

In this work, a new photovoltaic device was prepared. The device uses titanium (Ti) foil/TiO2 nanotubes as the photoanode and multi-walled carbon nanotubes (MWCNTs) as a photosensitizer. Titanium dioxide nanotube arrays (TiO2-NTs) were prepared by one-step anodic oxidation. Cut-MWCNTs with a length of less than 100 nm were obtained by the mixed-acid oxidation of MWCNTs. The two materials were combined to form a TiO2-NTs@cut-MWCNT heterostructure by electrophoresis. TiO2-NTs@cut-MWCNTs were characterized by field-emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD), which showed that the two materials were effectively combined. We fabricated the heterostructure into a photovoltaic device, showing an enhanced photocurrent response and an efficiency of 0.0138%, and explained this phenomenon by performing UV-vis absorption spectroscopy and electrochemical tests. It is hoped that this work can provide a reference value for the application of carbon nanotubes in photovoltaic devices. [ABSTRACT FROM AUTHOR]

Achieving multi-color luminescence with a single atomic center in transition metal complexes is a challenge. In this work, luminescent materials with tunable emission properties were realized by complexation between aluminum (III) ions with the ligands 3-hydroxyflavone (3-HF) and 5,7-dichloro-8-hydroxyquinoline (DCHQ). Aluminum (III) complexes with a single ligand emitted blue from 3-HF and green from DCHQ. High quantum yields (QYs) of 29.42% and 37.00% were also obtained, respectively. DFT calculations revealed details of the photophysical properties of the complexes. Correspondingly, cyan light emission was obtained if these two complexes were mixed together, from which the emission wavelength was located at 470 nm and the QY was 20.52%, under 290 nm excitation. More importantly, the cyan light emitted by the mixtures had selective sensitivity to different metal ions, resulting in either quenching the fluorescence (in the case of Fe3+) or enhancing the fluorescence (in the case of In3+). The fluorescence enhancement effect of In3+ on metal complexes has not been previously reported, neither for transition metal nor lanthanide ions. The linear quenching behavior of Fe3+ functions in the 50–700 μM concentration range, and the linear enhancement behavior of In3+ is demonstrated in the 300–800 mM concentration range. [ABSTRACT FROM AUTHOR]

The clinical use of anticancer drugs necessitates new technologies for their safe, sensitive, and selective detection. In this article, lanthanide (Eu3+ and Tb3+)-loaded γ-cyclodextrin nano-aggregates (ECA and TCA) are reported, which sensitively detects the anticancer drug irinotecan by fluorescence intensity changes. Fluorescent lanthanide (Eu3+ and Tb3+) complexes exhibit high fluorescence intensity, narrow and distinct emission bands, long fluorescence lifetime, and insensitivity to photobleaching. However, these lanthanide (Eu3+ and Tb3+) complexes are essentially hydrophobic, toxic, and non-biocompatible. Lanthanide (Eu3+ and Tb3+) complexes were loaded into naturally hydrophilic γ-cyclodextrin to form fluorescent nano-aggregates. The biological nontoxicity and cytocompatibility of ECA and TCA fluorescent nanoparticles were demonstrated by cytotoxicity experiments. The ECA and TCA fluorescence nanosensors can detect irinotecan selectively and sensitively through the change of fluorescence intensity, with detection limits of 6.80 μM and 2.89 μM, respectively. ECA can safely detect irinotecan in the cellular environment, while TCA can detect irinotecan intracellularly and is suitable for cell labeling. [ABSTRACT FROM AUTHOR]

Proteoglycans(PGs) are important glycosylated proteins found onthe cell surface and in the extracellular matrix. They are made upof a core protein with glycosaminoglycan (GAG) side chains. Variationsin composition and number of GAG side chains lead to a vast arrayof PG sizes and functions. Here we present a method for the synthesisof proteoglycan-mimetic graft copolymers (or neoproteoglycans) withtunable GAG side-chain composition. This is done using three differentGAGs: hyaluronan, chondroitin sulfate, and heparin. Hyaluronan isfunctionalized with a hydrazide-presenting linker. Either chondroitinsulfate or heparin is grafted by the reducing end on to the hyaluronanbackbone through reductive amination. PG mimics with heparin or chondroitinsulfate side chains and four different ratios of GAG side chain resultin graft copolymers with a wide range of sizes. The chemistry is confirmedthrough attentuated total reflectance Fourier transform infrared spectroscopy(ATR-FTIR) and 1H NMR. Effective hydrodynamic diameterand zeta potential are determined using dynamic light scattering andelectrophoretic mobility measurements. Graft copolymers were testedfor their ability to bind and deliver basic fibroblast growth factor(FGF-2) to mesenchymal stem cells (MSCs). The chondroitin sulfate-containinggraft copolymers successfully deliver FGF-2 to cells from surfaces.The lowest graft density of heparin-containing PG mimic also performswell with respect to growth factor delivery from a surface. This newmethod for preparation of GAG-based graft copolymers enables a widerange of graft density, and can be used to explore applications ofPG mimics as new biomaterials with tunable biochemical and biomechanicalfunctions. [ABSTRACT FROM AUTHOR]

In recent years, rare earth complexes have become famous for their unique luminescence characteristics, such as clear emission bands, long lifetimes, and high luminous quantum efficiency. Since lanthanide ions have relatively small absorption areas in the ultraviolet region, they absorb light weakly. However, the excitation can be improved via coordination with organic ligands and subsequent energy transfer from the ligand triplet state to a coordinated metal ion. Electrospinning is a processing method that can readily combine rare earth complexes with matrix materials, to obtain fiber membranes with high fluorescence efficiency and stable mechanical properties. Here, we report the application of fluorescent nanofibers to color-tunable materials and oxygen sensing materials by discussing the electrospinning techniques used to produce electrospun nanofibers containing lanthanide complexes. We then focus on the mechanism of luminescence of fluorescent nanofibers, discussing polymer-based membranes and ceramic-based membranes based on the main constituent materials of the fiber membranes. [ABSTRACT FROM AUTHOR]

Abstract: Near-IR surface plasmon resonance is used to characterize Teflon AF films for refractive index-based detection of the aromatic hydrocarbon contaminants benzene, toluene, and xylenes in water. The technique requires no sample preparation, and film sensitivity is found to be enhanced by oxygen plasma etching. A diffusion equation model is used to extract the diffusion and partition coefficients, which indicate film enrichment factors exceeding two orders of magnitude, permitting a limit of detection of 183, 105 and 55ppb for benzene, toluene, and xylenes, respectively. The effect of other potential interfering contaminants is quantified. [Copyright &y& Elsevier]

The direct delivery of growth factorsto sites of tissue healingis complicated by their relative instability. In many tissues, theglycosaminoglycan (GAG) side chains of proteoglycans like aggrecanstabilize growth factors in the pericellular and extracellular space,creating a local reservoir that can be accessed during a wound healingresponse. GAGs also regulate growth factor-receptor interactions atthe cell surface. Here we report the development of nanoparticlesfor growth factor delivery that mimic the size, GAG composition, andgrowth factor binding and stabilization of aggrecan. The aggrecan-mimeticnanoparticles are easy to assemble, and their structure and compositioncan be readily tuned to alter their physical and biological properties.We use basic fibroblast growth factor (FGF-2) as a model heparin-bindinggrowth factor, demonstrating that aggrecan-mimetic nanoparticles canpreserve its activity for more than three weeks. We evaluate FGF-2activity by measuring both the proliferation and metabolic activityof bone marrow stromal cells to demonstrate that chondroitin sulfate-basedaggrecan mimics are as effective as aggrecan, and heparin-based aggrecanmimics are superior to aggrecan as delivery vehicles for FGF-2. [ABSTRACT FROM AUTHOR]

Poly(vinyl chloride) (PVC), a synthetic polymer, is used in various biomedical applications, particularly in the development of catheters. PVC-based catheters are engineered for blood-contacting applications. However, these materials lack antimicrobial properties, resulting in bacterial proliferation and subsequent infections. To overcome this disadvantage, blood-compatible and antimicrobial polyphenolic tannin-based surface coatings, known as polyelectrolyte multilayers (PEMs), were adsorbed onto PVC for the first time. PEMs were created on reduced PVC (Red-PVC) or oxidized PVC (Oxi-PVC) substrates using the layer-by-layer (LbL) approach. An amino-functionalized polyphenolic tannin derivative (TN-NH 2), commercially known as Tanfloc, and an unmodified polyphenolic tannin (TN), commercially known as Weibull black, were assembled (15 layers) on Oxi-PVC or Red-PVC at pH 5.0. PVC substrates and PEMs were characterized through atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and water contact angle (WCA) measurements. The PEMs showed enhanced wettability compared to the unmodified PVC, with water contact angles ranging from 42° to 38°. The root mean square (R q) roughness of the PEMs ranged from 64.5 nm to 74.1 nm, while the unmodified PVC surface displayed a relatively smooth surface with a roughness of 5.4 nm. Stability tests demonstrated that the PEMs maintained their integrity in phosphate buffer (pH 7.4) over seven days at 37 ° C. The obtained PEMs were not toxic to human fibroblasts and human erythrocytes. The Live/Dead antimicrobial assay results indicated that the PEMs possessed biocidal activity against Pseudomonas aeruginosa (P. aeruginosa) and antiadhesive capacity toward Staphylococcus aureus (S. aureus) and P. aeruginosa after 24 h of incubation. Cytocompatible and antimicrobial tannin-based PEMs on modified PVC surfaces can represent a significant advancement in mitigating bacterial infections associated with PVC-based catheters. • Polyphenolic and amino-functionalized polyphenolic tannins were assembled on poly(vinyl chloride). • The surface coatings are cytocompatible toward fibroblast and red blood cells. • The surface coatings supported outstanding antiadhesive properties. • The surface coatings showed antimicrobial activity against Pseudomonas aeruginosa. • Surface coatings can mitigate bacterial infections associated with catheters. [ABSTRACT FROM AUTHOR]

Patients in hospital environments are susceptible to bacterial colonization, which can lead to infections. In this study, electrospun fibers were manufactured using poly(vinyl alcohol) (PVA) crosslinked with citric acid (CA) and incorporating the ionic liquid (IL) 1-hexadecyl-3-methylimidazolium chloride (C 16 MImCl) to prevent microbial growth and biofilm formation. The presence of CA and IL reduced the surface tension of the PVA solution (12% w/v) from 52.07 mN/m to 35.84 mN/m. CA was introduced into PVA solutions, and the resulting fibers were thermally crosslinked through esterification between PVA hydroxyl groups and CA. X-ray photoelectron spectroscopy (XPS) confirmed the presence of IL on the fiber surfaces. The IL acted as a surfactant, imparting plasticity to the electrospun fibers and enhancing homogeneity and mechanical properties. Before crosslinking, the PVA/CA/IL fibers exhibited an elongation at break (%) of approximately 140%, a tensile strength of 5.3 MPa, and an elastic modulus of 18.2 MPa. After cross-linking, the elongation at break reduced to 86%, the tensile strength increased to 7.6 MPa, and the elastic modulus increased to 88 MPa. Mechanical measurements confirmed the thermal crosslinking of the fibers, primarily because of the increased elastic modulus. Adhesion and proliferation tests with Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) indicated reduced bacterial adhesion and growth on the PVA/CA/IL fibers. Antimicrobial assays further confirmed a 50.73% and 69.42% increase in bactericidal activity against S. aureus and P. aeruginosa , respectively. The PVA/CA/IL fibers exhibit promising potential for producing antimicrobial materials to prevent the attachment and proliferation of microbial strains on solid surfaces. • The ionic liquid 1-hexadecyl-3-methylimidazolium was electrospuned with poly(vinyl alcohol)/citric acid. • The ionic liquid improved the electrospinnability of the polymer solutions. • The fibers were thermally cross-linked through esterification reaction. • The fibers containing the ionic liquid promoted anti-adhesive and antimicrobial properties. [ABSTRACT FROM AUTHOR]

• Chondroitin sulfate and gelatin surface coatings were assembled in water. • The surface coatings were associated with ionic liquids on poly(ethylene terephthalate). • The surface coatings prevented the ionic liquid cytotoxic effect on fibroblast cells. • The surface coatings containing an ionic liquid supported virucidal activity against the mouse hepatitis virus. The cytotoxicity of ionic liquids (ILs) in solution, including aqueous 1-n-hexadecyl-3-methylimidazolium chloride (C 16 MImCl), 1-n-hexadecyl-3-methylimidazolium methane sulfonate (C 16 MImMeS), and 1-n-hexadecyl pyridinium chloride monohydrate (C 16 PyrCl⋅H 2 O) solutions and polyelectrolyte multilayers (PEMs) containing ILs were investigated against mouse hepatitis virus (MHV-3) and fibroblast cells (L929). C 16 MImMeS and C 16 PyrCl⋅H 2 O exhibited virucidal activity against MHV-3 after 30 s of exposure at 662.31 nM and 744.88 nM, respectively. However, these ILs demonstrated considerable toxicity against fibroblast cells (2.0 × 105 cells/well) at 583 nM (C 16 MImCl), 498 nM (C 16 MImMeS), and 559 nM (C 16 PyrCl⋅H 2 O), limiting their direct application in aqueous solutions. Therefore, these ILs were combined with PEMs consisting of alternating 15 layers of gelatin (GE) and chondroitin sulfate (CS) to address this limitation. The PEMs were deposited on oxidized poly(ethylene terephthalate) (PET) using the layer-by-layer (LbL) approach. The ILs altered the relative surface adhesion force, reducing it from 4.08 nN on GE/CS PEM to the range between 2.23 and 3.10 nN on the GE/CS IL PEMs. The ILs enhanced surface electrostatic forces while decreasing adhesion forces on the surfaces. Incorporating ILs into the PEMs proved a promising strategy as they reduced the toxicity of the ILs towards L929 cells while maintaining their virucidal efficacy. The GE/CS PEM without IL did not exhibit virucidal activity against MHV-3. In contrast, GE/CS PEMs combined with C 16 MImMeS showed virucidal activity after 24 h, inactivating 99.99 % of the virus. The PEMs associated with the ILs were cytocompatible toward the L929 cells after a 48-hour incubation period. GE/CS IL PEMs hold promise as cytocompatible surface coatings for solid materials due to their durability and ability to prevent viral growth. [ABSTRACT FROM AUTHOR]

For humans, companion animals, and food producing animals, vaccination has been touted as the most successful medical intervention for the prevention of disease in the twentieth century. However, vaccination is not without problems. With the development of new and less reactogenic vaccine antigens, which take advantage of molecular recombinant technologies, also comes the need for more effective adjuvants that will facilitate the induction of adaptive immune responses. Furthermore, current vaccine adjuvants are successful at generating humoral or antibody mediated protection but many diseases currently plaguing humans and animals, such as tuberculosis and malaria, require cell mediated immunity for adequate protection. A comprehensive discussion is presented of current vaccine adjuvants, their effects on the induction of immune responses, and vaccine adjuvants that have shown promise in recent literature. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:1278–1316, 2009 [ABSTRACT FROM AUTHOR]

Abstract: When encapsulating proteins in polymer microspheres for sustained drug delivery there are three stages during which the stability of the protein must be maintained: (1) the fabrication of the microspheres, (2) the storage of the microspheres, and (3) the release of the encapsulated protein. This study focuses on the effects of polymer degradation products on the primary, secondary, and tertiary structure of tetanus toxoid, ovalbumin (Ova), and lysozyme after incubation for 0 or 20 days in the presence of ester (lactic acid and glycolic acid) and anhydride (sebacic acid and 1,6-bis(p-carboxyphenoxy)hexane) monomers. The structure and antigenicity or enzymatic activity of each protein in the presence of each monomer was quantified. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, circular dichroism, and fluorescence spectroscopy were used to assess/evaluate the primary, secondary, and tertiary structures of the proteins, respectively. Enzyme-linked immunosorbent assay was used to measure changes in the antigenicity of tetanus toxoid and Ova and a fluorescence-based assay was used to determine the enzymatic activity of lysozyme. Tetanus toxoid was found to be the most stable in the presence of anhydride monomers, while Ova was most stable in the presence of sebacic acid, and lysozyme was stable when incubated with all of the monomers studied. [Copyright &y& Elsevier]

• Water-uptake can be suppressed in methacrylate-based dental composites. • Hydrolytic degradation can be suppressed in methacrylate-based dental composites. • All-hydrocarbon nanogels can be incorporated into labile polymer network. • Incorporated nanogels do not change dental resin formulation. • Water-uptake and degradation depends on nanogel loading level. The objective of this study was to demonstrate an approach with potential to increase the life of dental restorative polymers in water, by maintaining their strength and toughness with varied content of inert or reactive styrenic pre-polymeric additives. It was hypothesized that addition of styrene-co-divinylbenzene nanogels to a conventional dimethacrylate resin (e.g. TEGDMA) would reduce its susceptibility towards hydrolytic degradation, while maintaining equivalent mechanical properties. Polymerization kinetics and functional group conversions were determined by Fourier transform infrared spectroscopy. Triple-detection gel permeation chromatography was used for nanogel particle characterization. A goniometer was used to measure water contact angle on experimental and control photocured polymers. Hydrolytic degradation and mass loss evaluation was performed after extended water storage of an intentionally hydrolytically degradable polymer. Resin viscosity was determined rheometrically and polymer mechanical properties were evaluated using three-point flexural testing with TEGDMA-nanogel formulations. The polymer network with highest level of nanogel loading (50 wt%) and the highest level of internal nanogel crosslinking (50 mol%) had the lowest degree of equilibrium swelling ratio and mass loss. The flexural modulus and ultimate strength of polymerized TEGDMA and styrenic nanogel-modified TEGDMA were not statistically different (p > 0.05). Due to improved shielding throughout the bulk of methacrylate-based polymers, including an example with an intentionally hydrolytically labile network structure, and a dramatic decrease of water uptake while maintaining equivalent mechanical properties, styrenic nanogel additives especially in high loading levels provide an excellent alternative to eliminate the adverse effects of water and presumably salivary fluids. [ABSTRACT FROM AUTHOR]

Water-soluble luminescent lanthanide complexes that can be excited with visible light could enable rapid detection of toxic anions and cations in biological systems. Eu3+-induced hyaluronic acid-chitosan aggregates (EIHCA) can improve the stability, biocompatibility, efficiency, and light absorption of luminescent Eu3+ complexes. Visible-range excitation may avoid phototoxicity associated with overexposure to UV light in biological and ecological applications. In this work, we synthesized and characterized series of EIHCA complexes having three N -donor heterocyclic ligands: 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (Dphen), 2,2′: 6′,2″-terpyridine (Tpy) and 1,10-phenanthroline monohydrate (Phen). These complexes possessed bright red fluorescence with a visible range excitation maximum. The photophysical properties of one formulation (we denote as EDL6) include fast quenching response (20 s) of the fluorescence, multi-selectivity, low limit of detection, and high quenching (K sv) values, enabling selective, rapid and sensitive recognition of Cr 2 O 7 2− and Fe3+ in aqueous solution. Furthermore, EDL6 exhibits cytocompatibility with mammalian cells that make these complexes promising biocompatible candidate as a safe replacement of organic fluorophores for fluorescence sensing applications. Thus, these new EIHCA complexes were successfully employed for the selective detection of hazardous materials in biological and aqueous environment samples. [Display omitted] • Eu3+-induced hyaluronic acid-chitosan aggregate containing a combination of N -heterocyclic ligands, were synthesized. • These nanoparticles serve as fluorescent sensors with visible-range excitation, water stability and bio-compatibility. • Eu3+-complexes are fast and multi-responsive fluorescence sensors to detect Cr(VI) and Fe(III) in water. • Eu3+-fluorescent complex exhibits cell membrane permeability enabling detection of ions in live cell cultures. [ABSTRACT FROM AUTHOR]

In this work free-standing gels formed from gellan gum (GG) by solvent evaporation are coated with polysaccharide-based polyelectrolyte multilayers, using the layer-by-layer approach. We show that PEMs composed of iota -carrageenan (CAR) and three different natural polycationic polymers have composition-dependent antimicrobial properties, and support mammalian cell growth. Cationic polymers (chitosan (CHT), N , N , N -trimethyl chitosan (TMC), and an amino-functionalized tannin derivative (TN)) are individually assembled with the anionic iota -carrageenan (CAR) at pH 5.0. PEMs (15-layers) are alternately deposited on the GG film. The GG film and coated GG films with PEMs are characterized by infrared spectroscopy with attenuated total reflectance (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and water contact angle (WCA) measurements. The TN/CAR coating provides a hydrophobic (WCA = 127°) and rough surface (R q = 243 ± 48 nm), and the TMC/CAR coating provides a hydrophilic surface (WCA = 78°) with the lowest roughness (R q = 97 ± 12 nm). Polymer coatings promote stability and durability of the GG film, and introduce antimicrobial properties against Gram-negative (Salmonella enteritidis) and Gram-positive (Staphylococcus aureus) bacteria. The films are also cytocompatible. Therefore, they have properties that can be further developed as wound dressings and food packaging. • A commercial gellan gum is characterized, supporting stable films due to the metallic ions presence in its composition. • The solvent evaporation method provides a stiffer gellan gum film. • The film is coated with polyelectrolyte multilayers due to the carboxylate moieties on the gellan gum. • Chitosan/ iota -carrageenan and N , N , N -trimethyl chitosan/ iota -carrageenan coatings support antimicrobial activities. • The coated films can be applied in the food and biomedical fields. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Graphene oxide/MXene composite membranes were modified by urea. • The nanochannel size of GMU membranes can be adjusted with angstrom precision. • GMU membranes exhibited high water permeance and excellent ion selectivity. • GMU membranes demonstrated good long-term stability over 30 days. Two-dimensional (2D) membranes demonstrate good performance in molecular and ion separation due to their unique layer structure. However, the sieving performance of 2D membranes is severely limited by drawbacks such as poor stability and low mass transfer rates. Here, we propose a design strategy using urea as a cross-linking agent to construct stable and regular nanochannels inside the graphene oxide/MXene (GO/MXene) composite membranes. More importantly, by changing the composition, the effective interlayer spacing of the membrane can be easily adjusted within 4.47–8.92 Å with angstrom-level precision for tunable ion sieving. The composite membrane exhibits high water permeance (79.58 L m−2 h−1 bar−1) and excellent small molecule dye rejection (>99 %). Moreover, depending on the ionic valence state, the membrane exhibits significant ion sieving. The good Cl−/SO 4 2− selectivity (11.64) makes it a promising alternative to conventional ion exchange membranes. This study demonstrates an innovative and facile way to construct 2D lamellar membranes with stable structures for efficient and precise separation. [ABSTRACT FROM AUTHOR]

• Surface coatings were engineered to treat bacterial corn streak disease. • The surface coatings protect the corn leaves from bacterial infection. • The surface coating reduces the synthon of bacterial corn streak dissemination. • A commercial ionic liquid has in vitro but not in vivo antimicrobial activity. • The filming-forming property of polymers is essential to protect the corn leaves. The bacterial corn streak disease, caused by Xanthomonas vasicola pv. vasculorum (Xvv) has emerged as a threat to corn production due to its rapid spread and resistance to conventional agrochemicals. Therefore, this study proposes polymeric surface coatings based on chitosan (CS) and tannins (TN) as antimicrobial agents against Xvv. The coatings were formed via the layer-by-layer (LbL) approach on oxidized polystyrene (PS). The coatings increased the wettability and roughness of the surfaces. In vitro assays measuring the minimum inhibitory and minimum bactericidal concentrations (MIC and MBC) demonstrated the antimicrobial activity of CS and TN. Coatings deposited on PS exhibited in vitro anti-adhesive properties against Xvv. The in vitro antimicrobial results were compared with control assays performed with an ionic liquid (IL). The IL was also associated with the polymeric coatings. Polymeric coatings, with or without IL, were deposited on corn leaves for in vivo assays. The IL had no activity against Xvv , and its presence in the CS solution seemed to impair the coating deposition on the corn leaves. However, the in vivo assays confirmed the protective efficacy of the polymeric coatings against Xvv infection, acting as physical barriers. The surface coatings also significantly reduced the Xvv symptoms in infected plants even after the disease spread. These outcomes were attributed to the film-forming ability of CS and TN polymers, the coatings' antimicrobial action, and the LbL efficiency in depositing the coatings on the corn leaves. This study introduces a promising environmentally and economically viable strategy for combating bacterial corn streak disease using biodegradable, cytocompatible natural polymers. The surface coatings offer a sustainable method to address bacterial corn disease, overcoming the limitations of agrochemicals. [ABSTRACT FROM AUTHOR]

• The MOF and GO nanosheets were tightly stacked through the π-π effect. • The shortened transport path of the MOF/GO membrane improved the water permeability. • MOF/GO composite membrane can efficiently separate cationic and anionic dyes. Two-dimensional materials are widely used in membrane separation, but the loose distribution and severe expansion between graphene oxide (GO) nanosheets limit its application. Here, we introduce a two-dimensional MOF material into the GO membrane to enhance its water permeance and separation performance. The MOF/GO composite membrane was prepared by vacuum filtration. The MOF and GO nanosheets were tightly stacked through the π-π effect, and the shortened transmission path and enhanced pore structure greatly improved the water permeance of the composite membrane. The MOF/GO membrane exhibited a high water permeance of 56.94 L m−2 h−1 bar−1. The rejection rates of methylene blue and was as methyl orange dyes were as high as 99.79% and 99.11%, respectively. At increased dye concentration, the rejection rate of methylene blue was still maintained greater than 99%. Dye rejection after 18 h of continuous operation remains above 90%. This work provides new ideas for improving membrane separation materials. The combination of two-dimensional heterogeneous materials can result in synergistic advantages for the development of composite membranes with high water permeance and high rejection rate. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, a surface modification strategy using natural biopolymers on titanium is proposed to improve bone healing and promote rapid and successful osseointegration of orthopedic implants. Titania nanotubes were fabricated via an anodization process and the surfaces were further modified with polyelectrolyte multilayers (PEMs) based on Tanfloc (a cationic tannin derivative) and glycosaminoglycans (heparin and hyaluronic acid). Scanning electron microscopy (SEM), water contact angle measurements, and X-ray photoelectron spectroscopy were used to characterize the surfaces. Adipose-derived stem cells (ADSCs) were seeded on the surfaces, and the cell viability, adhesion, and proliferation were investigated. Osteogenesis was induced and osteogenic differentiation of human ADSCs on the surfaces was evaluated via mineralization and protein expression assays, immunofluorescent staining, and SEM. The Tanfloc/heparin PEMs on titania nanotubes improved the rate of osteogenic differentiation of ADSCs as well as the bone mineral deposition, and is therefore a promising approach for use in orthopedic implants. [ABSTRACT FROM AUTHOR]

Water shortages have become a major problem facing the world today. Membrane separation technology is commonly used in water treatment applications. The development of new materials for water treatment can reduce the energy required for water treatment, reduce cost, and improve efficiency. The unique structure and properties of graphene and silica make them attractive materials for preparation of nanofiltration membranes for water treatment. We have successfully prepared a graphene oxide/silica (GO/SiO2) hybrid composite materials by in situ hydrolysis, using tetraethyl orthosilicate (TEOS) as a silicon source in an alkaline environment. The chemistry and structure of these materials are characterized by TEM, FTIR, Raman, and XPS of GO and the GO/SiO2 composite. BET porosimetry reveals that the total pore volume of the composite is 2.84 cm3 g−1, the specific surface area is 2897 m2 g−1, and the average pore diameter is 3.97 nm. We prepared GO membranes and GO/SiO2 composite membranes by vacuum suction filtration. The morphology of the membrane was observed by FESEM and AFM. The composite membrane has a larger surface roughness (Rms = 9.39). We also tested the thermal stability by TGA, and hydrophilicity by water contact angle measurements. The water permeance of the composite membrane is up to 229.15 L m−2 h−1 bar−1, and the rejection of the rhodamine B dye molecules is as high as 99%. The GO/SiO2 hybrid composite membrane has good hydrophilicity and thermal stability, high water permeance and rejection, and can be developed as a high-performance material for water treatment. [ABSTRACT FROM AUTHOR]

Chemical modification of polysaccharides is an important route to enhance, develop or change polysaccharide properties. In this study, carboxymethylation of kappa-carrageenan (KC) with monochloroacetic acid was performed to achieve different degrees of substitution (DS) of carboxymethyl-kappa-carrageenan (CMKC). The degree of substitution ranged from 0.8 to 1.6 and was calculated from the 1H NMR spectra. The chemical structure of the CMKCs was further characterized by FT-IR, and 13C NMR. FT-IR confirmed the carboxymethylation. Carboxymethylation increased viscosity of KC in water and decreased viscosity of KC in synthetic human sweat. Tests with human adipose derived stem cells showed higher viability and lower cytotoxicity for CMKCs when compared to KC. CMKCs showed no hemolytic activity to human red blood cells. CMKCs have increased antioxidant activity compared to KC. In antibacterial assays, CMKCs with DS of 0.8, 1.0 and 1.2 exhibited growth inhibition against Staphylococcus aureus , Bacillus cereus , Escherichia coli and Pseudomonas aeruginosa. CMKC with DS ranging from 1.0 to 1.2 are good candidate biomaterials for cell-contacting applications. Unlabelled Image • Carboxymethyl-κ-carrageenan with degrees of substitution 0.8–1.6 were synthesized. • Carboxymethylation enhanced biological activities compared to κ-carrageenan. • Cytocompatibility and radical scavenging activity were increased. • The polymer shows growth inhibition for Gram-positive and Gram-negative bacteria. [ABSTRACT FROM AUTHOR]

To obtain pectin-based films is challenging due to the aqueous instability of polyelectrolyte mixtures. We overcome this issue by blending chitosan to pectin of high O -methoxylation degree (56%), followed by solvent evaporation. A durable film containing 74 wt% pectin content was produced and used as an adsorbent material toward Cu(II) ions. Kinetic and adsorption equilibrium studies showed that the pseudo-second-order and Sips isotherm models adjusted well to the experimental data, respectively. Langmuir isotherm indicated a maximum adsorption capacity (q m) for Cu(II) removal of 29.20 mg g−1. Differential scanning calorimetry, contact angle measurements, and X-ray photoelectron spectroscopy confirm the adsorption. The chemisorption plays an essential role in the process; thereby, the film reusability is low. After adsorption, the cytocompatible film/Cu(II) pair prevents the proliferation of Escherichia coli. • A physically crosslinked film contains high pectin content (74 wt%). • The film presents sorption capacity for Cu(II) ions of 29.20 mg g−1. • The chemisorption plays an essential role in the Cu(II) adsorption. • After adsorption, the film/Cu(II) has cytocompatibility for mammalian cells. • The film/Cu(II) prevents the spreading of E. coli on its surface. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract Here we report a new and straightforward method to yield durable polyelectrolyte complexes (hydrogel PECs) from gellan gum (GG) and chitosan (CS) assemblies, without metallic and covalent crosslinking agents, commonly used to produce GG and CS-based hydrogels, respectively. This new approach overcomes challenges of obtaining stable and durable GG-based hydrogels with structural homogeneity, avoiding precipitation and aqueous instability, typical of PEC-based materials. PECs are created by blending CS:GG solutions (at 60 °C) with GG:CS weight ratios between 80:20 to 40:60. X-ray photoelectron spectroscopy (XPS) analysis shows that CS-GG chains are interacting by electrostatic and intermolecular forces, conferring a high degree of association to the washed PECs, characteristic of self-assembling of polymer chains. The CS:GG weight ratio can be tuned to improve polyelectrolyte complex (PEC) high porosity, stability, porous homogeneity, and degradation rate. Physical and thermosensitive CS/GG-based hydrogels can have advantages over conventional materials produced by chemical processes. Highlights • Chitosan/gellan gum polyelectrolyte complexes were prepared. • Chitosan:gellan gum weight ratio plays a significant role in the features of the materials. • The materials present stability, self-assembling, structural homogeneity and slow degradation rate. [ABSTRACT FROM AUTHOR]

The reduced graphene oxide-gold nanoparticle (rGO-Au NP) membranes are prepared by vacuum filtration method. The sizes of the Au NPs on the surface of the rGO are about 8-10 nm, and the lattice spacing of Au NPs is 0.0241 nm, which is relative to the cubic lattice of the gold crystal. The layer-by-layer stacking structure of rGO-Au NP membrane can be observed clearly by field emission scanning electron microscopy. The water flux of the rGO-Au NP membrane is as high as 204.1 L m−2 h−1 bar−1, and its retention for Rhodamine B (RhB) is as high as 99.79%. [ABSTRACT FROM AUTHOR]

Graphene has promising potential in several fields because of its unique and brilliant properties, and graphene-based composites are studied for nanofiltration because of their chemical stability and thermal resistance. Nanometals are used for compositing with graphene and its derivatives, such as Ag, Au, TiO2, and Cu. Graphene-based/nanometal membranes have remarkable performance in water treatment, antibacterial properties, and so on. In this review, we introduce the separation mechanism and fabrication method of graphene-based/nanometal composite membranes and then summarize the recent developments. Therefore, additional applications of graphene-based/nanometal composite membranes can be expected, and this paper reviews the current research trends. [ABSTRACT FROM AUTHOR]

To obtain nanofiltration membranes with high-performance in desalination and water purification, membranes of graphene oxide (GO), reduced graphene oxide (rGO) and GO/polyacrylamide (PAM) are prepared by a vacuum filtration method. This method is conducted in aqueous solution without any organic solvents. The graphene-based membranes (GBMs) are characterized by UV-visible spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscopy, atomic force microscopy, scanning electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy. The hydrophilicity of GBMs is also evaluated by contact angle measurement. The interlayer spacing of GO membrane (0.85 nm), GO/PAM membrane (0.68 nm) and rGO membrane (0.36 nm) are measured by X-ray diffraction. The performance of the GBMs is evaluated on a dead-end filtration device. The water flux and retention of rhodamine B of the membranes are 399.04 L m−2 h−1 bar−1 and 85.03% (GO), 188.89 L m−2 h−1 bar−1 and 95.43% (GO/PAM), 85.85 L m−2 h−1 bar−1 and 97.06% (rGO), respectively. The GO/PAM membrane has the best comprehensive separation performance because of its proper interlayer spacing. GO/PAM membranes provide potential advantages in the design of high-performance membranes for molecular separation and water purification. [ABSTRACT FROM AUTHOR]

Processing stable polysaccharide membranes with suitable mechanical properties has been challenging for applications in wound healing and tissue engineering. Here we expand the characterization of pectin/chitosan (PT/CS) membranes (without covalent crosslinking), which we recently reported. Membranes containing pectin (PT) excess were formed, and PT/CS ratio can be tuned to enhance the mechanical strength, and to modulate hydrophilicity and cytocompatibility. The surface wettability and swelling properties of the polyelectrolyte complexes (PECs) played an important role to promote the attachment of stem cells. These PECs membranes have ultimate tensile strength similar to that of human skin, which is on the order of ten times higher than similar previously reported polysaccharide materials. We show for the first time that these new PT/CS membranes may promote anchorage, adhesion and support human stem cell growth, making them candidate materials for tissue engineering purposes. [ABSTRACT FROM AUTHOR]

Poly(ε-caprolactone) (PCL) is a hydrophobic and cytocompatible aliphatic polyester that has been used to produce PCL-based nanofibrous for both wound healing and tissue repair. However, the high hydrophobicity and low water adsorptive have been challenges for developing PCL-based materials for use in tissue engineering field. Here, we report a new polymer (a hydrophilic amino-functionalized tannin (TN)) that is associated with PCL for developing PCL-TN blends at different PCL:TN weight ratios (100:0, 95:5, 85:15 and 78:22). PCL:TN ratio may be tuned to modulate hydrophilicity and cytocompatibility of the nanofibers. The neutralization step and surface wettability played an important role in the attachment of human adipose-derived stem cells (ADSC cells) on PCL-TN membranes. Also, fluorescence images confirmed great proliferation of ADSC cells on the PCL-TN electrospun surfaces. Yet, neutralized PCL-TN nanofibers promoted bactericidal activity against Pseudomonas aeruginosa. These membranes have potential to be used as scaffolds for tissue engineering purposes. [ABSTRACT FROM AUTHOR]

Carboxymethylcellulose (CMC) and keratin nanoparticle (KNP) hydrogels were obtained, characterized, and applied as drug delivery systems (DDSs) for the first time. Lyophilized CMC/KNP mixtures containing 10, 25, and 50 wt% of KNPs were kept at 170 °C for 90 min to crosslink CMC chains through a solid-state reaction with the KNPs. The hydrogels were characterized by infrared spectroscopy, thermal analyses, X-ray diffraction, mechanical measurements, and scanning electron microscopy. The infrared spectra indicated the formation of ester and amide linkages between crosslinked CMC and KNPs. The elastic modulus of the hydrogel containing 10 wt% KNPs was 2-fold higher than that of the hydrogel containing 50 wt% KNPs. The mechanical properties influenced the hydrogel stability and water uptake. The anti-inflammatory prednisolone (PRED) drug was incorporated into the hydrogels, and the release mechanism was investigated. The hydrogels supported PRED release by drug desorption for approximately 360 h. A sustained release mechanism was achieved. The CMC/KNP and CMC/KNP/PRED hydrogels were cytocompatible toward mammalian cells. The CMC/KNP/PRED set imparted the highest cell viability after 7 days of incubation. This study showed a straightforward procedure to create DDSs (chemically crosslinked) based on polysaccharides and proteins for efficient PRED delivery. [ABSTRACT FROM AUTHOR]

Processing water-soluble polysaccharides, like pectin (PT), into materials with desirable stability and mechanical properties has been challenging. Here we report a new method to create water stable and mechanical resistant polyelectrolyte complex (PEC) membranes from PT and chitosan (CS) assemblies, without covalent crosslinking. This new method overcomes challenges of obtaining stable and durable complexes, by performing the complexation at low pH, enabling complex formation even when using an excess of PT, and when using PT with high degree of O- methoxylation. By performing the complexation at low pH, the complexes form with a high degree of intermolecular association, instead of forming by electrostatic complexation. This method avoids precipitation, and overcomes the aqueous instability typical of PT/CS complexes. After neutralization, the PEC membranes display features characteristic of a high degree of intermolecular association because of the self-assembling of polymer chains. The PT/CS ratio can be tuned to enhance the mechanical strength (σ = 39 MPa) of the membranes. These polysaccharide-based materials can demonstrate advantages over synthetic materials for technological applications. [ABSTRACT FROM AUTHOR]

Chitosan/alginate (CHT/ALG) and magnetic CHT/ALG/Fe 3 O 4 @SiO 2 composites were successfully prepared and used as adsorbent materials to remove Pb(II) from aqueous systems. New hydrogel beads were yielded through an unpublished methodology, examining the ionic strength of the chitosan (CHT) solutions. Polyvalent cations and toxic cross-linking agents such as glutaraldehyde and epichlorohydrin, frequently used to prepare CHT/ALG-based materials were not used in this study. The samples were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, thermal analysis (TAG/DSC), and zeta potential measurements. The addition of Fe 3 O 4 @SiO 2 (8 ± 3 nm) significantly modified the surface morphology of the composites. The CHT/ALG/Fe 3 O 4 @SiO 2 (8) hydrogel comprising the highest Fe 3 O 4 @SiO 2 content (8.0 wt%), displayed magnetic feature and zeta potential of −76.8 mV at pH 6.0. Kinetic and equilibrium adsorption studies reveal that Elovich and Redlich-Peterson mathematical models provide the best fits for the experimental data, respectively. The magnetic composite CHT/ALG/Fe 3 O 4 @SiO 2 (8) had maximum adsorption capacity (q m ) of 234.77 mg g −1 and adsorption/desorption cycles designed its reuse performance. The CHT/ALG/Fe 3 O 4 @SiO 2 (8) hydrogel was applied to treat battery effluent, achieving 99.04% Pb(II) removal, and diminishing the turbidity from 73 to 3.0 NTU. Wastewater and battery effluents contaminated with Pb(II) may be treated using an eco-friendly magnetic hybrid material based on CHT/ALG/Fe 3 O 4 @SiO 2 as the adsorbent. [ABSTRACT FROM AUTHOR]

Novel Stöber derived silica nanoparticles doped with europium complexes [Eu(tta) 3 phen]by two-step alkaline hydrolysis method have been fabricated in order to design stable luminescent hybrid nanoparticles with fine particle size. Isotactic polypropylene (iPP) was doped with long-lifetime (τ = 859.2 µs) luminescent nanoparticles via twin screw extrusion. The composition, structure and luminescence properties of the resulting hybrid nanoparticles were investigated in detail. STEM revealed that europium complexes were encapsulated homogenously and stably in nano silica. The luminescence measurements combined with bright red color photographs confirm the red light emission due to trivalent europium ions, while the intensity increases with the increase of corresponding doped concentrations of SiO 2 -Eu 3+ nanoparticles in iPP hybrid materials. The melt processable luminescent optical fibers reported here is a novel application of rare earth complexes that can be used to develop new photonic and electronic materials. [ABSTRACT FROM AUTHOR]

Membrane modification, membrane preparations, nanofiltrations, smart membranes, stimuli-responsiveness Keywords: membrane modification; membrane preparations; nanofiltrations; smart membranes; stimuli-responsiveness EN membrane modification membrane preparations nanofiltrations smart membranes stimuli-responsiveness 1 1 1 02/27/23 20230223 NES 230223 B Stimuli-Responsive Smart Membranes b In article number 2211983, Yanxin Wang, Jianguo Tang, Linjun Huang, Jun Chen, and co-workers review the recent development in stimuli-responsive smart membranes for nanofiltration. This review also provides a critical analysis of the current advances in smart membranes and insights into remaining challenges and future directions. [Extracted from the article]

Proteoglycans have vital biochemical and biomechanical functions. Their proteolytic degradation results in loss of these functions. We have previously reported nonprotein proteoglycan-mimetic graft copolymers that stabilize and deliver growth factors and are not subject to proteases. Here we expand our investigation of these proteoglycan mimics by also investigating their effects on hydrogel mechanical properties. Four polysaccharide side chains, chondroitin sulfate, heparin, dextran, and dextran sulfate, are each grafted to a hyaluronan backbone. The polysaccharides and graft copolymers are added to agarose hydrogels. Cyclic compression and stress relaxation tests reveal how the addition of the polysaccharides and graft copolymers influence hydrogel modulus. Cells encapsulated in agarose hydrogels containing chondroitin sulfate and the chondroitin sulfate graft copolymer have decreased cell viability and metabolic activity compared to cells in unmodified agarose hydrogels. These multifunctional additives can be used to improve both the biochemistry and biomechanics of materials, warranting further optimization to overcome the potentially negative effects these may have on cell viability and activity. [ABSTRACT FROM AUTHOR]

The well-defined lanthanide co-doped upconversion nanoparticles(UCNPs) had been synthesized using a simple solvothermal route at 150 °C, which was lower than previous reports. The shuttle-like and spherical UCNPs co-doped by Yb 3+ /Tm 3+ had been prepared, respectively. The morphology, crystal phase and size distribution of various UCNPs could be easily controlled. The growth mechanism and morphology transition of UCNPs had been deduced by schematic diagram. UC luminescence could be tuned by employing different host lattices (GdF 3 , YF 3 , NaGdF 4 and NaYF 4 ). NaGdF 4 :Yb 3+ /Tm 3+ displayed the strongest UC luminescence at 475 nm among four kinds of UCNPs, and its emission intensity was almost 10 times higher than that of NaYF 4 :Yb 3+ /Tm 3+ . UC mechanism had been determined by energy level diagrams. It’s revealed that the accumulation and energy transfer of Gd 3+ could be demonstrated in polycrystalline structure. The work provided a simple method for preparation of UCNPs with tunable UC luminescence. [ABSTRACT FROM AUTHOR]

The influence of a graphene/silver (G/A) nanocomposite coating layer on the microstructural evolution and surface oxidation of a Mg–Ni–La hydride is investigated systematically by XRD, SEM, EDS and HRTEM in detail. SEM and EDS reveal that the existence of the G/A composite prevents the electrode from pulverizing and oxidizing. The oxygen content in the surface of the electrode is reduced from 21% to 10% after 50 cycles for a Mg-Ni-La electrode with 0.2 mass fraction of G/A. The crystallization process of the amorphous electrodes coated by G/A is reduced compared to the uncoated electrode and the stable Mg 2 NiH 4 , α-Mg, MgH 2 and La oxihydroxide phases are present with the grain size about 40–60 nm after 50 charge/discharge cycles. The G/A coating reduces the corrosion and oxidation of the electrode alloy and provides both a pathway for hydrogen diffusion and active sites for the redox reaction of hydrogen. All of these factors result in a significant improvement of the discharge capacity by about 200 mAh g −1 in each cycle (after activation) for Mg-Ni-La electrodes with 0.2 mass fraction of G/A nanocomposites. [ABSTRACT FROM AUTHOR]

In this work, a luminescent lanthanide complex, namely, Eu(tta) 3 phen (Eu = europium, tta = 2-thenoyltrifluoroacetone, phen = 1, 10-phenanthroline) is used as a luminescent dopant to prepare fluorescent nanofiber films. The resulting nanofibers (CS/PEO-SiO 2 @Eu(tta) 3 phen) are composed of chitosan and polyethylene oxide containing silica nanoparticles, encapsulating the Eu(tta) 3 phen. The nanofibers are stabilized by treatment with sodium bicarbonate (NaHCO 3) aqueous solution as neutralizer and then repeatedly washed with deionized water. A more stable Na-CS/PEO-SiO 2 @Eu(tta) 3 phen fiber film is obtained as a fluorescence sensor for Cu2+ ions. The Na-CS/PEO-SiO 2 @Eu(tta) 3 phen has high sensitivity, and a wide detection range. The response is linear in the concentration range from 10 to 90 μmol/L, and the detection limit is 0.826 μmol/L. In addition, Na-CS/PEO-SiO 2 @Eu(tta) 3 phen nanofiber film can be used as a recyclable sensor for the detection of Cu2+ ions in aqueous solution due to its good recyclability, selectivity and rapid optical response. • CS/PEO-SiO 2 @Eu(tta) 3 phen film is stabilized by neutralization with weak base. • Na-CS/PEO-SiO 2 @Eu(tta) 3 phen film can be quenched after Cu2+ solution is dropped on it. • Na-CS/PEO-SiO 2 @Eu(tta) 3 phen film is capable of accurately detecting 10–90 μmol/L of Cu2+, LOD is 0.826 μmol/L. • Na-CS/PEO-SiO 2 @Eu(tta) 3 phen film can still be used as a Cu2+ sensor after 5 cycles of use. [ABSTRACT FROM AUTHOR]