Successful Surface Modification Research Articles

Treating wool fibers with chitosan-based nano-composites for enhancing the antimicrobial properties

Environmentally friendly finishing methods for imparting antimicrobial properties to various textiles are very desirable. The purpose of the present study is to investigate the synthesis, characterization, and application of various chitosan (Ch) derivatives containing Ag, Cu and Zn nanoparticles (NPS) on wool yarn. The Ch loaded with various NPs was studied by Scanning Electron Microscopy (SEM), Dynamic light scattering (DLS), Fourier Transform Infra-Red (FTIR) and Differential Scanning Calorimetry (DSC). Wool yarns were treated with Ch-NPs and the treated samples were analyzed by SEM. The weight gain results indicated the successful surface modification of wool fibers with Ch-NPs. The treated samples showed excellent antimicrobial activities (~ 100%) against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The treated samples had generally very high antimicrobial activities (> 80%) even after 10 washing cycles. The surface modification of wool fibers with Ch-NPs can be considered as an environmentally friendly method for antimicrobial finishing.

Cu Nanoparticle-Modified High-Density Polyethylene Monofilament and Its Antifouling Performance on Fishing Netting

Cu nanoparticles (CuNPs) were modified by organic surfactant, then CuNP-modified high-density polyethylene (CuNP/HDPE) monofilaments were prepared by melt spinning. The effect of CuNP content on the morphology and properties of nanocomposite monofilaments was investigated. FT-IR and dynamic light scattering proved the successful surface modification for CuNP. Scanning electron microscope was used to observe the dispersed behavior of the CuNP. When the CuNP content was less than 1.0 wt%, the CuNPs were well dispersed in these nanocomposite monofilaments, and the increase of crystallization rate, the breaking strength, and knot strength were observed by differential scanning calorimeter and tensile test. Therefore, nanocomposite monofilaments showed comparable properties at low CuNP contents. With increasing CuNP content, the width of tanδ peak and △Ea for α-relaxation from dynamic mechanical analysis were increased, indicating more amorphous components near the crystalline regions. In addition, burst release of Cu ions in seawater was observed. The coupon tests demonstrated that CuNPs could significantly improve antibiofouling performance of CuNP/HDPE fishing netting. CuNP/HDPE fishing netting have a strong potential for using in marine antifouling mitigation.

Preparation and Characterization of Soy Protein Isolate-Based Nanocomposite Films with Cellulose Nanofibers and Nano-Silica via Silane Grafting.

Soy protein isolate (SPI) has attracted considerable attention in the field of packaging technology due to its easy processability, biodegradability, and good film-forming characteristics. However, SPI-based films often suffer from inferior mechanical properties and high moisture sensitivity, thus restricting their practical application. In the present study, herein, a biobased nanocomposite film was developed by cross-linking SPI matrix from the synergistic reinforcement of cellulose nanofibers (CNF) and nano-silica (NS) particles. First, we functionalized the CNF with NS using a silane agent (KH560) as an efficient platform to enhance the interfacial interaction between SPI and CNF/NS, resulting from the epoxy-dominated cross-linking reaction. The chemical structure, thermal stability, and morphology of the resultant nanocomposite films were comprehensively investigated via Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). These results supported successful surface modification and indicated that the surface-tailored CNF/NS nanohybrid possesses excellent adhesion with SPI matrix through covalent and hydrogen-bonding interactions. The integration of CNF/NS into SPI resulted in nanocomposite films with an improved tensile strength (6.65 MPa), representing a 90.54% increase compared with the pristine SPI film. Moreover, the resulting composites had a significantly decreased water vapor permeation and a higher water contact angle (91.75°) than that of the unmodified film. The proposed strategy of synergistic reinforcements in the biobased composites may be a promising and green approach to address the critical limitations of plant protein-based materials in practical applications.

Novel Bifunctional Nanofiller (Bioactive\Antimicrobial) for Improving Dental Adhesives Efficacy

Purpose: The objective of this study was to develop novel bio-composite Nanofiller (Quaternary polyethyleneimine\ Hydroxyapatite, QPEI/HAp), which combines the antibacterial activity of polymeric quaternary ammonium salt and the multi-advantages of Hydroxyapatite nanoparticles for improving biological and physico-mechanical properties of Dental Adhesives. Materials and Methods: Hydroxyapatite (HAp) nano rods were produced by hydrothermal process and coated by Polyethyleneimine (PEI) via electrostatic adsorption, followed by two steps polymeric reaction; tertiary amination and quaternization. The resulting powder was characterized using XRD, FTIR and TEM before and after polymer coating, and bioactivity was evaluated after 7 days soaking in simulated body fluid using XRD analysis. An experimental ethanolbased one-bottle adhesive resin was formulated with 0.2, 0.5, 1, 2 and 5% QPEI/HAp nanofiller. The formulated adhesive resins were evaluated for their colloidal stability, antibacterial activity, Ultimate Tensile Strength, and Micro-Shear bond strength to dentin. Results: Powder characterization confirmed successful surface modification of Hydroxyapatite nanoparticles with PEI polymer; the particles presented a high crystallinity with typical chemical groups and mean size around 20 nanometers. XRD analysis revealed nucleation of apatite crystals on the surface of QPEI/HAp nanoparticles after soaking in SBF; confirming their bioactivity. Lower contents of modified nanoparticles showed little or no aggregation tendency and good colloidal stability in the adhesive solution with Zeta potential of 30.6 mV. Antibacterial outcomes of PEI against S. mutans was significantly higher than that of MDPB in Clearfil Protect bond; a commercial adhesive used as control (P<0.05). The addition of 0.2 wt. % modified nano-hydroxyapatite resulted in higher values of Ultimate Tensile and Micro-Shear bond strength than other tested adhesives and commercial Clearfil S3 Bond (all-in-one adhesive); (P<0.05). Conclusion: Incorporation of 0.2 wt. % QPEI-HAp nanoparticles significantly improved the adhesive properties and may be promising multifunctional filler for dental adhesive resin.

Enhanced electrocatalytic behaviour of gold electrodes modified with ZnO nanoparticles through organophosphonate chemistry

Stable immobilization and homogenous distribution of ZnO nanostructures on solid substrates can play a fundamental role in developing nanostructured biosensing devices. In this work we studied how phosphonic acid-terminated self-assembled monolayers (SAMP of 1) can enhance the electrocatalytic behaviour of ZnO nanoparticles (NPs) immobilized on gold surface. It is well known that alkanethiols can form uniform and conformal monolayers on gold through the thiol group and it has already been shown that ZnO surface can be modified by organophosphonates. Here we focus on the application of this chemistry as a tool for the fabrication of designed architectures of ZnO nanostructures on gold electrodes. Successful surface modification was verified by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. Our results indicate the formation of highly stable arrays of ZnO nanoparticles. As a proof of concept, the novel electrodes developed were tested in electrochemical assays for the detection of the transgenic protein neomycin phosphotransferase II (NPTII), showing enhanced electrocatalytic stability in immunosensor applications. The target protein could be detected down to nanomolar level by using the difference in charge transfer resistance (ΔRct) recorded in impedance spectroscopy measurements.

Enhanced capacity of fluoride scavenging from contaminated water by nano-architectural reorientation of cerium-incorporated hydrous iron oxide with graphene oxide

An in situ wet chemical deposition method has been applied for the successful surface modification of Ce (IV)-incorporated hydrous Fe(III) oxide (CIHFO) with a hydrophilic graphene precursor, graphene oxide (GO). The surface area of as-prepared composite (GO-CIHFO) has enhanced (189.57 m2 g-1) compared with that of pristine CIHFO (140.711 m2 g-1) and has irregular surface morphology consisting of microcrystals (~ 2-3 nm) and mesoporous (3.5486 nm) structure. The GO-CIHFO composite shows enhanced fluoride scavenging capacity (136.24 mg F g-1) than GO (3 mg F g-1) and pristine CIHFO (32.62 mg F g-1) at pH 7.0. Also, in acidic pH range and at 323 K temperature, the Langmuir capacity of as-prepared composite is 190.61 mg F g-1. It has been observed that fluoride removal by GO-CIHFO occurs from solutions obeying pseudo-second-order kinetics and multilayer adsorption process. The film/boundary layer diffusion process is also the rate-determining step. The nature of the adsorption reaction is reasonably spontaneous and endothermic in thermodynamic sense. It was observed that 1.2 g.L-1 of GO-CIHFO dosage can effectively optimise the fluoride level of natural groundwater samples (9.05 mg L-1) to the desirable permissible limit. Reactivation of used material up to a level of 73.77% with a solution of alkaline pH has proposed reusability of nanocomposites ensuring sustainability of the proposed material as fluoride scavenger in future.

TEMPO-oxidized cellulose nanofiber/kafirin protein thin film crosslinked by Maillard reaction

Mixtures of cellulose nanofiber and protein have gained attention as a material having potential application such as bio-plastics and biopolymer based packaging film. Herein, an efficient protocol for the formation of kafirin protein thin film plasticized with PEG-300 and reinforced with 0.5% TEMPO-oxidized CNF was developed. In this regards cellulose nanofibers were prepared using a high-pressure homogenizer at ≈ 241 MPa pressure for 30 cycles and the resultant nanofibers was found to be of average diameter 89–60 nm under SEM observation. Further, ultrasound-mediated regio-selective oxidation of nanofibers was carried out using 2,2,6,6-tetramethylpiperidine (TEMPO) catalyst. FTIR and Solid-state 13C CP/MAS NMR spectroscopy reveals successful surface modification of nanofiber. The conductometry titration data demonstrated 32.81% substitution of the hydroxyl group by carbonyl group. Furthermore, the effect of TEMPO-oxidized cellulose nanofiber content (0–1%) on kafirin protein structure and nanocomposite film was thoroughly investigated. The cross-linking between carbonyl group of nanofiber and amine groups of kafirin protein is attributed to the possible Maillard reaction at 80 °C, which was evidenced by FTIR. An increase in cross-linking between nanofiber and protein results in the simultaneous increase in crystallinity and thermal stability when 0.5% of TO-CNF was incorporated in kafirin. Meanwhile, additional attempts have been made to improve mechanical strength and water vapor transmission rate. Swelling studies suggests better stability with no swelling, however, at pH 10.6 film starts to swell over a period of time and then starts to disintegrate. Overall, when comparing 0% with 0.5% of TO-CNF, 0.5% has shown better stability.

Polyluminol Modified Carbon Nanotube Electrodes for Electrochemical Capacitors

Luminol exhibits electrochemical redox activity when electropolymerized on various substrates, and has been used for electrocatalysis and biosensors [1, 2]. This electrochemical behavior is due to the presence of different amine functional groups within the polymer structure. Recent studies have shown that introducing amine groups on a carbon surface improves the charge storage capacity and the conductivity of the obtained material [3]. Our work aims to leverage the electrochemical properties of polyluminol (Plum) for electrochemical capacitors (ECs). Firstly, the Plum was synthesized using a chemical approach and characterized using spectroscopic methods and electrochemical analyses. Secondly, the polymer was deposited on carbon nanotubes (CNT) to enhance the charge storage capacity for ECs. The chemical composition of the polymer was found to be a mixture of benzoid and quinoid segments, bonded via secondary (NH) or tertiary amine (=N-) groups, respectively. Such functionalities facilitated chemical, thermal, and electrochemical stability of the polymer. The composite electrode material was obtained by in-situ chemical polymerization of Plum on CNT. Morphological analyses of CNT confirmed the increase of the Plum thickness on CNT with polymerization time, reaching a saturation point of 6.5 nm. In addition, a 4x increase of charge storage capacity with good electrode stability was observed compared to bare CNT over a potential window of 1.2 V as seen in figure 1. Study of the redox reaction kinetics revealed a mostly capacitive contribution of the polymer on CNT. This work showed the successful surface modification and engineering of CNT using a simple and effective fabrication method, which is suitable for large-scale fabrication of composite electrode materials for ECs. G.-F. Zhang and H.-Y. Chen, Analytica Chimica Acta, 419, 25 (2000).A. Sassolas, L. J. Blum and B. D. Leca-Bouvier, Sensors and Actuators B: Chemical, 139, 214 (2009).N. Phattharasupakun, J. Wutthiprom, P. Suktha, N. Ma and M. Sawangphruk, Journal of The Electrochemical Society, 165, A609 (2018). Figure 1

Facile synthesis of tetrazolo[1,5-a]pyrimidine with the aid of an effective gallic acid nanomagnetic catalyst

The present work is the first report of nano-Fe3O4@SiO2-NH-gallic acid in multicomponent reactions as a catalyst. One-pot condensation of various aromatic aldehydes, ß-ketoesters and 5-aminotetrazole to deliver the desired tetrazolo[1,5-a]pyrimidine derivatives is investigated. It involves successful surface modification of Fe3O4@SiO2-NH2 as a potent magnetic support with a well-known natural acid which attracts considerable interests because of its applications in different sciences. This reusable magnetically separable nanocatalyst provides a convenient and reliable method for high yield tetrazole derivatives synthesis in short reaction times with wide variety range of the products and facile isolation. Acid grafting on the surface of amine-functionalized silica-coated magnetic nanoparticles confirmed by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and energy-dispersive X-ray (EDX) analysis techniques. Structural characterization included scanning electron microscopy (SEM) images along with transmission electron microscopy (TEM) images and vibrating sample magnetometer (VSM) curve applied for morphology and magnetism type determination of the resulted nanocatalyst, respectively.

Improvements on biological and antimicrobial properties of titanium modified by AgNPs-loaded chitosan-heparin polyelectrolyte multilayers.

Microbial infection around dental implants is a major cause for the loss of devices, including soft tissue infection in early period, post-operation peri-implantitis, and osseointegration failure. Silver nanoparticles (AgNPs) with wide antimicrobial spectrum, strong antimicrobial effect and hypotoxicity, as well as low incidence of antibiotic resistance, are widely involved in biomedical applications. Herein, firmly anchoring AgNPs onto the surface of implants through physical-chemical reaction is likely to relieve the above issues. In this study, AgNPs were biosynthesized by a simple and "green" method with chitosan (CS) as stabilizing and reducing agents. Then, AgNPs-loaded CS-heparin polyelectrolyte multilayers (PEMs) were constructed on alkali-heat treated titanium (Ti) substrates via layer-by-layer (LbL) self-assembly technique. The successful surface modification could be confirmed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), and the constructed system could provide the continuous release of Ag+ over 28 days till mucosa healing. In short, this work revealed that the construction of multilayer coatings containing AgNPs on Ti substrates promoted adhesion and proliferation of human gingival fibroblasts (HGFs) and also enhanced the antimicrobial properties. This manifests the LbL technique is a viable and promising method for forming continuous antimicrobial coatings, to reduce microbial infection and improve the quality of peri-implant soft tissue seal. The preparation process of AgNPs-loaded CS-heparin PEMs on Ti substrate.

Designing bioactive porous titanium interfaces to balance mechanical properties and in vitro cells behavior towards increased osseointegration

Titanium implant failures are mainly related to stress shielding phenomenon and the poor cell interaction with host bone tissue. The development of bioactive and biomimetic Ti scaffolds for bone regeneration remains a challenge which needs the design of Ti implants with enhanced osseointegration. In this context, 4 types of titanium samples were fabricated using conventional powder metallurgy, fully dense, dense etched, porous Ti, and porous etched Ti. Porous samples were manufactured by space holder technique, using ammonium bicarbonate particles as spacer in three different ranges of particle size (100–200 μm, 250–355 μm and 355–500 μm). Substrates were chemically etched by immersion in fluorhydric acid at different times (125 and 625 s) and subsequently, were characterized from a micro-structural, topographical and mechanical point of view. Etched surfaces showed an additional roughness preferentially located inside pores. In vitro tests showed that all substrates were biocompatible (80% of cell viability), confirming cell adhesion of premioblastic cells. Similarly, osteoblast showed similar cell proliferation rates at 4 days, however, higher cell metabolic activity was observed in fully dense and dense etched surfaces at 7 days. In contrast, a significant increase of alkaline phosphatase enzyme expression was observed in porous and porous etched samples compared to control surfaces (dense and dense etched), noticing the suitable surface modification parameters (porosity and roughness) to improve cell differentiation. Furthermore, the presence of pores and rough surfaces of porous Ti substrates remarkably decreased macrophage activation reducing the M1 phenotype polarization as well M1 cell marker expression. Thus, a successful surface modification of porous Ti scaffolds has been performed towards a reduction on stress shielding phenomenon and enhancement of bone osseointegration, achieving a biomechanical and biofunctional equilibrium.

Surface modification of cellulose nanocrystal using succinic anhydride and its effects on poly(butylene succinate) based composites

Cellulose nanocrystals (CNCs) extracted from microcrystalline cellulose, were modified by succinic anhydride to give succinic CNCs (SCNCs). Successful surface modification of SCNCs was confirmed by results of FTIR, FE-SEM, contact angle measurement and dispersity test, and SCNCs were then subjected to melt blending with poly(butylene succinate) (PBS) to prepare nanocomposites. Meanwhile, PBS/CNC nanocomposites were also prepared through same procedure as references. The morphology, thermal and mechanical properties and crystallization properties of PBS/SCNC nanocomposites with increasing SCNCs content from 0 to 7 wt% were investigated. PBS/SCNC nanocomposites exhibit better thermal stability than that of PBS/CNCs, which is mainly ascribed to less sulfate groups on CNC surfaces and more hydrogen bond effects between PBS carbonyl groups and ester groups from SCNCs. Young’s modulus and yield strength of PBS/SCNCs are higher than that of PBS/CNC nanocomposites, which is primarily attributed to the homogeneous dispersion of SCNCs in PBS matrix, confirmed by FE-SEM images. This work is valuable for design of PBS-based nanocomposites with enhanced thermal and mechanical properties.

Enhanced dielectric permittivity in surface-modified graphene/PVDF composites prepared by an electrospinning-hot pressing method

In the present work, the surface-modified graphene (SMG)/poly(vinylidene fluoride) (PVDF) fibrous membranes obtained from the electrospinning were treated by the hot pressing in the laminating mode to form the SMG/PVDF composites. The SMG was prepared by subjecting the graphene oxide to silane modification, NaBH4 reduction, and PVDF grafting in sequence. The successful surface modification of graphene was confirmed by TEM, XPS, Raman spectroscopy, FTIR, WAXD, and TGA. Furthermore, the structures of SMG/PVDF composites fabricated by the electrospinning-hot pressing method were studied by SEM, FTIR, and WAXD, which exhibited the well dispersion of SMG in the PVDF matrix. Finally, the investigation showed that the dielectric permittivities of SMG/PVDF composites increased with the SMG content, which were significantly higher than that of pristine PVDF. The dielectric permittivity of SMG (16 wt%)/PVDF composite (83.8) at 1000 Hz was found to be ten-fold that of the corresponding value of pristine PVDF (8.3) with a relatively low dielectric loss factor (0.34) and a relatively high thermal conductivity (0.679 W/mK).

Effect of Mussel‐Inspired Poly(Dopamine)‐Functionalized Carbon Nanotubes/Graphene Nanohybrids on Interfacial Adhesion of Soy Protein‐Based Nanocomposites

The demands for strong integrated biopolymer materials have substantially increased across various industries. In this study, a biomimic strategy was proposed to prepare the poly(dopamine)‐functionalized carbon nanotubes (PDCNTs) via mussel‐inspired chemistry. The graphene dispersion was prepared in aqueous bovine serum albumin solution by ultrasonic treatment through a facile and green approach. Inspired by the excellent integration of mechanical properties and hierarchical nano/microscale structure of natural nacre, we fabricated soy isolate protein (SPI)‐based nanocomposite film with 2D graphene nanosheets and 1D surface‐functionalized PDCNTs through a layer‐by‐layer assembly process. The morphology and thickness of graphene nanosheets were analyzed by atomic force microscopy. The successful surface modification of PDCNTs was confirmed by X‐ray photoelectron spectroscopy and transmission electron microscopy. The cross‐linking hierarchical structure of the SPI hybrid film was observed in scanning electron microscopy images. A combination of multiple interfacial interactions and enhanced adhesion between the PDCNTs‐graphene conjugation and SPI matrix resulted in a remarkable improvement in the mechanical properties of the SPI‐based nanocomposites. When compared with the unmodified film, the tensile strength and elongation at break of the hybrid film were simultaneously increased by 158.93 and 78.67%, respectively. As a result of the enhanced tortuosity effect, the water vapor permeability was significantly reduced by 33.65%. In addition, the resultant film also possessed favorable water resistance, thermal stability, and ultraviolet–visible light barrier behavior. This work provided a novel bio‐inspired interfacial toughening strategy for constructing high performance biopolymer nanocomposites. POLYM. COMPOS., 40:E1649–E1661, 2019. © 2018 Society of Plastics Engineers

β-Agarase immobilized on tannic acid-modified Fe3O4 nanoparticles for efficient preparation of bioactive neoagaro-oligosaccharide

β-Agarase was immobilized by using tannic acid modified-Fe3O4 magnetic nanoparticles (TA-MNPs) as a supportmaterial. The MNPs were synthesized by improved chemical coprecipitation method and modified with TA for agarase immobilization. TA-MNPs and immobilized β-agarase were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and thermal gravimetric analysis (TGA), all of which indicated the successful surface modification of MNPs with TA and the immobilization of β-agarase. The optimal immobilization conditions for 25 mg TA-MNPs included 100 r/min oscillation speed, immobilization time of 2 h, immobilization temperature of 15 °C, and initial β-agarase concentration of 3 mL (480 U). Immobilized β-agarase showed better pH and thermal stability and excellent reusability than the free enzyme. Results revealed the promising application of β-agarase-TA-MNPs for the preparation of neoagaro-oligosaccharides with different averagepolymerizationdegrees and varying activities in the antioxidant.

Preparation and structural characterization of surface modified microporous bacterial cellulose scaffolds: A potential material for skin regeneration applications in vitro and in vivo

This study reports the fabrication of porogen-induced, surface-modified, 3-dimensionally microporous regenerated bacterial cellulose (rBC)/gelatin (3DMP rBC/G) scaffolds for skin regeneration applications. Round shaped gelatin microspheres (GMS), fabricated using a water-in-oil emulsion (WOE) method, were utilized as the porogen. The dissolution of GMS from the solution casted BC scaffolds led to surface-modified microporous rBC. The scaffolds were characterized using field emission scanning electron microscopy (FE-SEM) and elemental analysis. FE-SEM analysis confirmed the regular microporosity of the 3DMP rBC/G scaffolds, while elemental analysis confirmed the successful surface modification of cellulose with gelatin. In vitro tests showed good adhesion and proliferation of human keratinocytes (HaCaT) on the 3DMP rBC/G scaffolds during 7 days of incubation. Confocal microscopy showed penetration of HaCaT cells into the scaffolds, up to 300 μm in depth. In vivo wound healing and skin regeneration experiments, in experimental mice, showed complete skin regeneration within 2 weeks. The wound closure efficacy of the 3DMP rBC/G scaffolds was much higher (93%) than that of the control (47%) and pure BC-treated (63%) wounds. These results indicated that our 3DMP rBC/G scaffolds represent future candidate materials for skin regeneration applications.

Surface zwitterionization of PVDF VIPS membranes for oil and water separation

This work aims at applying a combined polymerization and membrane surface-modification process, in order to hydrophilize poly(vinylidene fluoride) membranes prepared by vapor-induced phase separation (VIPS), and eventually make them suitable for low transmembrane pressure (ΔP = 0.5 bar) membrane separation of various oil-in-water (O/W) emulsions. Styrene and sulfobetaine monomers were mixed and allowed to react while the PVDF membrane was in contact with the reactive mixture, enabling self-assembling of the random polymer on the membrane as it was formed. Reaction parameters were optimized, and it was found that a solid content of 5 wt%, a styrene/SBMA ratio of 40/60 and a reaction time of 5 h led to very hydrophilic membrane (water contact angle: 12°). The combination of chemical analyses evidenced the successful and controlled surface modification process. Physical analyses showed that deviating from the optimized conditions of styrene/SBMA ratio led to the formation of agglomerates (styrene-rich or SBMA-rich), associated to low porosity, and high coating density. The membranes were used to separate emulsions of toluene/W, hexane/W, hexadecane/W, diesel/W and soybean oil/W, leading to separation efficiency of 99.0%, 99.2%, 99.1%, 99.0% and 99.0%, respectively. This work thus presents a new avenue for surface modification of membrane with extremely efficient copolymers for which there is no common solvent, and brings several evidences of the suitability of VIPS membrane for cost-effective membrane separation of various emulsions.

Surface modification of finely dispersed NaCl

The first successful surface modification of finely dispersed NaCl particles was achieved during their synthesis in situ in the presence of CuCl2 and polyvinylpyrrolidone. Obtained layered structure is stable to washing with polar organic solvents and to environmental moisture.

Enhanced In Vitro Biocompatibility and Water Dispersibility of Magnetite and Cobalt Ferrite Nanoparticles Employed as ROS Formation Enhancer in Radiation Cancer Therapy.

Efficient magnetic reactive oxygen species (ROS) formation enhancing agents after X-ray treatment are realized by functionalizing superparamagnetic magnetite (Fe3 O4 ) and Co-ferrite (CoFe2 O4 ) nanoparticles with self-assembled monolayers (SAMs). The Fe3 O4 and CoFe2 O4 nanoparticles are synthesized using Massart's coprecipitation technique. Successful surface modification with the SAM forming compounds 1-methyl-3-(dodecylphosphonic acid) imidazolium bromide, or (2-{2-[2-hydroxy-ethoxy]-ethoxy}-ethyl phosphonic acid provides biocompatibility and long-term stability of the Fe3 O4 and CoFe2 O4 nanoparticles in cell media. The SAM-stabilized ferrite nanoparticles are characterized with dynamic light scattering, X-ray powder diffraction, a superconducting quantum interference device, Fourier transform infrared attenuated total reflectance spectroscopy, zeta potential measurements, and thermogravimetric analysis. The impact of the SAM-stabilized nanoparticles on the viability of the MCF-7 cells and healthy human umbilical vein endothelial cells (HUVECs) is assessed using the neutral red assay. Under X-ray exposure with a single dosage of 1 Gy the intracellular SAM stabilized Fe3 O4 and CoFe2 O4 nanoparticles are observed to increase the level of ROS in MCF-7 breast cancer cells but not in healthy HUVECs. The drastic ROS enhancement is associated with very low dose modifying factors for a survival fraction of 50%. This significant ROS enhancement effect by SAM-stabilized Fe3 O4 and CoFe2 O4 nanoparticles constitutes their excellent applicability in radiation therapy.

PMMA/TEMPO-oxidized cellulose nanofiber nanocomposite with improved mechanical properties, high transparency and tunable birefringence

Recently, cellulose nanofibers (CNFs) have been developed as a very popular renewable and biodegradable nanofiller material for polymer nanocomposites. However, achieving good dispersion in a polymer matrix for effective reinforcement is still a challenge because CNFs are hydrophilic, whereas most polymers are hydrophobic. In this study, we report the poly(methyl methacrylate)/2,2,6,6-tetramethylpiperidyl-1-oxyl oxidized CNFs (PMMA/TOCN) nanocomposites, which show good dispersion, improved mechanical properties, excellent transparency, as well as controllable birefringence using a simple surface-modification procedure of TOCN with amine-functionalized poly(ethylene glycol). Studies conducted using transmission electron microscopy and fourier transform infrared spectroscopy showed that TOCNs were homogenously dispersed in the PMMA matrix without aggregation due to the successful surface modification of TOCN. Moreover, the nanocomposites were highly transparent and the transmittance in the visible region was as high as approximately 90%. In addition, we firstly discovered that the birefringence of the nanocomposite could be controlled by the amount of TOCN added, even achieving zero birefringence. More importantly, the tensile strength and Young’s modulus of PMMA were significantly improved with the addition of TOCN. Such well-dispersed TOCN-based nanocomposites with high transparency, controllable birefringence and enhanced mechanical properties exhibit great potential for the applications in the optical devices and in the engineering field.