Removal of Methylene Blue and Congo Red Using a Chitosan-Graphene Oxide-Electrosprayed Functionalized Polymeric Nanofiber Membrane.

Untreated textile effluent may contain toxic organic pollutants that can have negative impacts on the ecosystem. Among the harmful chemicals present in dyeing wastewater, there are two frequently used organic dyes: methylene blue (cationic) and congo red (anionic). The current study presents investigations on a novel two-tier nanocomposite membrane, i.e., a top layer formed of electrosprayed chitosan-graphene oxide and a bottom layer consisting of an ethylene diamine functionalized polyacrylonitrile electrospun nanofiber for the simultaneous removal of the congo red and methylene blue dyes. The fabricated nanocomposite was characterized using FT-IR spectroscopy, scanning electron microscopy, UV-visible spectroscopy, and Drop Shape Analyzer. Isotherm modeling was used to determine the efficiency of dye adsorption for the electrosprayed nanocomposite membrane and the confirmed maximum adsorptive capacities of 182.5 mg/g for congo red and 219.3 mg/g for methylene blue, which fits with the Langmuir isotherm model, suggesting uniform single-layer adsorption. It was also discovered that the adsorbent preferred an acidic pH level for the removal of congo red and a basic pH level for the removal of methylene blue. The gained results can be a first step for the development of new wastewater cleaning techniques.

Chitosan-Graphene Oxide Dip-Coated Polyacrylonitrile-Ethylenediamine Electrospun Nanofiber Membrane for Removal of the Dye Stuffs Methylene Blue and Congo Red.

Textile wastewater accommodates many toxic organic contaminants that could potentially threaten the ecosystem if left untreated. Methylene blue is a toxic, non-biodegradable, cationic dye that is reportedly observed in significant amounts in the textile effluent stream as it is widely used to dye silk and cotton fabrics. Congo red is a carcinogenic anionic dye commonly used in the textile industry. This study reports an investigation of methylene blue and Congo red removal using a chitosan-graphene oxide dip-coated electrospun nanofiber membrane. The fabricated nanocomposite was characterized using Scanning Electron Microscopy (SEM), FT-IR Spectroscopy, Raman Spectroscopy, UV-vis Spectroscopy, Drop Shape Analyzer, and X-ray Diffraction. The isotherm modeling confirmed a maximum adsorptive capacity of 201 mg/g for methylene blue and 152 mg/g for Congo red, which were well fitted with a Langmuir isotherm model indicating homogenous monolayer adsorption.

Polyester Fabric with Fluorescent Properties Using Microwave Technology for Anti-Counterfeiting Applications.

The article presented concerns the application of fluorescein as a fluorescent material for anti-counterfeiting technology which will allow the labeling and identification of legitimate articles in the textile field. Fluorescein has been applied to polyester fabrics by microwave irradiation technique in the presence of a UV absorber. Thus, its presence in the textile substrate is detectable following an excitation at a specific wavelength belonging to the Ultra-violet zone, which makes this material very effective for tracking and detecting counterfeit articles. Fluorescent samples are characterized morphologically by scanning electron microscopy (SEM) and quantitatively by optical spectroscopy such as reflectance and transmission measurements. The treated samples show under UV light a yellowish green emission with a slight yellow coloration of the polyester fiber. The UV absorber applied to the fluorescent solution improves the light resistance of the treated samples by 25%. Their addition to the bath can also ensure the production of a protective fabric against UV.

Microwave Assisted Conversion of an Amino Acid Into a Fluorescent Solution.

Microwave assisted synthesis is a well established method in organic and inorganic chemistry. It is also used in material science to realize novel carbon nanoparticles exhibiting fluorescence properties. The results presented here are related to a microwave driven solvothermal process used for the conversion of amino acid and 1,2-diaminoethane into fluorescent solutions. Arginine, lysine and glycine were used as amino acids. The process temperatures are set in the range of 80° to 140 °C and the maximum process pressure is 4.5 bar. The process duration is set from 5 to 30 minutes. The fluorescence effect is increased with increasing temperature. The prepared aqueous fluorescent solutions can be used as media to induce fluorescence in textile substrates. The current study can be understood as a first proof-of-concept of a very simple microwave-assisted solvothermal synthesis of fluorescent compounds useful for the modification of different substrates.

Comparison of methods for determining the effectiveness of antibacterial functionalized textiles.

Antimicrobial functionalization of textiles is important for various applications, such as protection of textile materials from decomposition, generation of more effective wound dressings, and the prevention of infections or malodors resulting from bacterial growth. In order to test the efficacy of new products, their antibacterial activity needs to be evaluated. At present, several different procedures are being used for this purpose, hindering comparisons among different studies. The present paper compares five of these assays using a sample panel of different textiles functionalized with copper (Cu) and silver (Ag) as antibacterial agents, and discusses the suitability of these methods for different analytical requirements. Bacterial viability was determined by measuring the optical density at 600 nm, a colorimetric assay based on MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide) conversion, an agar diffusion assay, and colony formation, either after culturing in media containing textile samples, or after recovery from textiles soaked with bacterial suspension. All experiments were performed with a Gram-negative (Escherichia coli) and a Gram-positive (Staphylococcus warneri) model organism. In general, the results yielded by the different methods were of good comparability. To identify the most suitable test system for the particular type of antibacterial coating, several factors need to be taken into account, such as choosing appropriate endpoints for analyzing passive or active antibacterial effects, selection of relevant microorganisms, correcting for potential interference by leaching of colored textile coatings, required hands on time, and the necessary sensitivity.

A Natural Based Method for Hydrophobic Treatment of Natural Fiber Material.

A treatment for hydrophobic functionalization of natural fiber materials is developed. This hydrophobic treatment is based mainly on natural products. As hydrophobic component the natural Tung Oil is used, which is originally a compound used for wood conservation purposes. The application on textile is done in a padding process under presence of an oxidative agent. For the current investigations a fiber felt from linen was used. The hydrophobic effect is determined by the concentration of Tung Oil and the duration of a thermal drying process. The hydrophobic effect is investigated by capillary rise tests and contact angle measurements. Scanning electron microscopy SEM is used to investigate the surface topography of the fiber material and the deposited hydrophobic material. Altogether, an interesting and promising method for hydrophobisation of natural fibers is developed, which could especially be used as part of a production process of a fiber reinforced composite material, mainly based on natural products.

Nanoporous Thin Films and Binary Nanoparticle Superlattices Created by Directed Self-Assembly of Block Copolymer Hybrid Materials.

The design and development of well-defined, functional nanostructures via self-assembly is one of the key objectives in current nanotechnology. Block copolymer-based hybrid materials are attractive candidates for the fabrication of multifunctional nanostructures, which provide the building blocks for more complex nanoarchitectures and nanodevices. However, one of the major challenges lies in controlling the structure formation in these hybrid materials by guiding the self-assembly of the block copolymer. Here, hierarchical nanoporous structures are fabricated via guided multistep self-assembly of diblock copolymer micellar solutions onto hydrophilic solid substrates. The core of polystyrene-block-poly[4-vinylpyridine] micelles serves as a nanoreactor for the preparation of size-controlled gold nanoparticles. Deposition of thin films of the micellar solution in combination with a nonselective cosolvent (THF), on hydrophilic surfaces leads to the formation of hierarchical nanoporous structures. The micellar films exhibit two different pore diameters and a total pore density of more than 10(10) holes per cm2. Control over the pore diameter is achieved by adapting the molecular weight of the polystyrene-block-poly[4-vinylpyridine] diblock copolymer. Moreover, the porous morphology is used as a template for the fabrication of bimetallic nanostructured thin films. The PS-b-P4VP template is subsequently removed by oxygen plasma etching, leaving behind binary nanoparticle structures that mimic the original thin film morphology.

Impact of silver nanoparticles and silver ions on innate immune cells.

Silver is commonly used as an antibacterial agent, e.g., in various medical applications, and the availability of silver nanoparticles (AgNP) has fueled this development. Their antibacterial properties are well defined, whereas there are concerns regarding unknown and potentially harmful effects of AgNPs on immune cells and an ongoing immune reaction. Aim of the present study is a comparison of the effects of AgNPs and ionic silver (Ag+) on cells of the innate immune system, in particular on neutrophil granulocytes and macrophages. The AgNPs were synthesized within hydroxylated polyester dendrimer templates via an in situ approach, generating five kinds of AgNPs with mean diameters from 2.0 to 34.7 nm.4 No impact is observed on phagocytosis and oxidative burst, as well as activation of the promoter for the pro-inflammatory cytokine TNF-alpha. In contrast, both AgNPs and Ag+, but not the dendrimer templates, trigger the release of neutrophil extracellular traps and inhibit the formation of nitric monoxide. On the molecular level, AgNPs and Ag+ cause elevated intracellular levels of reactive oxygen species and the second messenger Zn2+. Moreover, protein phosphatases are inhibited by an oxidative mechanism. Taken together, there are several effects of AgNPs on neutrophil granulocytes and macrophages in vitro, but these are not specific for AgNP, instead they are also observed with Ag+, and Ag+ released from AgNPs seems to be the component responsible for most of the particles' immunomodulatory activity.

Chitosan(PEO)/silica hybrid nanofibers as a potential biomaterial for bone regeneration.

New hybrid nanofibers prepared with chitosan (CTS), containing a total amount of polyethylene oxide (PEO) down to 3.6wt.%, and silica precursors were produced by electrospinning. The solution of modified sol-gel particles contained tetraethoxysilane (TEOS) and the organosilane 3-glycidyloxypropyltriethoxysilane (GPTEOS). This is rending stable solution toward gelation and contributing in covalent bonding with chitosan. The fibers encompass advantages of biocompatible polymer template silicate components to form self-assembled core-shell structure of the polymer CTS/PEO encapsulated by the silica. Potential applicability of this hybrid material to bone tissue engineering was studied examining its cellular compatibility and bioactivity. The nanofiber matrices were proved cytocompatible when seeded with bone-forming 7F2-cells, promoting attachment and proliferation over 7 days. These found to enhance a fast apatite formation by incorporation of Ca(2+) ions and subsequent immersion in modified simulated body fluid (m-SBF). The tunable properties of these hybrid nanofibers can find applications as active biomaterials in bone repair and regeneration.

Modified silica sol coatings for surface enhancement of leather.

The presented study reports on differently modified silica sols for coating applications on leather. Silica sols are prepared by acidic hydrolysis of tetraethoxysilane and modified by silane compounds with fluorinated and non-fluorinated alkylgroups. In contrast to many earlier investigations regarding sol-gel applications on leather, no acrylic resin is used together with the silica sols when applying on leather. The modified silica particles are supposed to aggregate after application, forming thus a modified silica coating on the leather substrate. Scanning electron microscopy investigation shows that the applied silica coatings do not fill up or close the pores of the leather substrate. However, even if the pores of the leather are not sealed by this sol-gel coating, an improvement of the water repellent and oil repellent properties of the leather substrates are observed. These improved properties of leather by application of modified silica sols can provide the opportunity to develop sol-gel products for leather materials present in daily life.

Inorganic/organic (SiO2)/PEO hybrid electrospun nanofibers produced from a modified sol and their surface modification possibilities.

Ceramic silica (SiO(2)) hybrid nanofibers were prepared by electrospinning of solutions containing biocompatible polymer and modified silica precursors. The new hybrid nanofibers are based on polyethylene oxide (PEO) and a new solution of modified sol-gel particles of mixture containing tetraethoxysilane (TEOS) and 3-glycidyloxypropyltriethoxysilane (GPTEOS) in a weight ratio of 3:1. Adding high-molecular-weight PEO into the silica sol is found to enhance the formation of the silica nanofibers and leads to reduce the water-soluble carrying polymer down to 1.2%wt. Transmission electron microscopy (TEM) and attenuated total reflection fourier transformation infrared ATR-FTIR measurements are suggested that PEO is encapsulated by the silica component. This excellent formulation renders electrospinning of SiO(2) a robust process for an easy production of controllable silicate nanofibrous matrices. For instance, nanofibers with average diameter down to 400 nm are accessible by varying the weight ratio between the polymer and the inorganic precursor. These are reduced to 120 nm after the pyrolysis process. Moreover, the surface of the nanofibers could be easily modified, either by Al(3+) leading to aluminium silicate coatings, or by incorporation of Ca(2+) ions and subsequent bioactive hydroxyl carbonate apatite (HAP) formation. These hybrid silica nanofibers are possess a unique collective properties can have a great impact either in high-temperature reinforced materials and filtration or in biomedical applications such as in dentistry and bone tissue engineering.

Silver Nanoparticles in SiO2 Microspheres - Preparation by Spray Drying and Use as Antimicrobial Agent.

Silver nanoparticles embedded in SiO2 particles of micrometer size are prepared using spray drying. The spray drying is performed with a SiO2 sol (solvent water:ethanol 4: 1) containing SiO2 and silver particles of nanometer size. During spray drying the SiO2 nanoparticles aggregate to SiO2 microspheres whereas the silver particles exhibit only a small tendency of aggregation and keep their nanometer size. However under special conditions also the formation of crystalline silver rods is observed. The antibacterial activity of the resulting Ag/SiO2 powders is determined against the bacteria Escherichia coli and Bacillus subtilis. Because of this antibacterial acitivity and the fact that the powder of SiO2 microspheres exhibits a good dispersibility, such materials have an immense potential to be used as antimicrobial additive in processes like master batch or fiber production.