Dyeing of m-Aramid Fibers in Ionic Liquids.

Aramids represent a class of high-performance fibers with outstanding properties and manifold technical applications, e.g., in flame-retardant protective clothing for firefighters and soldiers. However, the dyeing of aramid fibers is accompanied by several economic and ecological disadvantages, resulting in a high consumption of water, energy and chemicals. In this study, a new and innovative dyeing procedure for m-aramid fibers using ionic liquids (ILs) is presented. The most relevant parameters of IL-dyed fibers, such as tensile strength, elongation and fastness towards washing, rubbing and light, were determined systematically. In summary, all aramid textiles dyed in ILs show similar or even better results than the conventionally dyed samples. In conclusion, we have successfully paved the way for a new, eco-friendly and more sustainable dyeing process for aramids in the near future.

Antimycotic influence of beta-cyclodextrin complexes--in vitro measurements using laser nephelometry in microtiter plates.

To determine the in vitro susceptibility of fungal organisms to beta-cyclodextrin (CD) complexes with the antifungal agents econazole-nitrate (EC) and ciclopirox-olamine (CI), a fast, rapid and simple method using laser nephelometry in 96-microtiter plate is used. The antimycotic influence of the complexes against Candida albicans DSM 11225 and Candida krusei ATCC 6258 species was determined using this method. A rapid inhibition and even killing of both fungi was observed only above certain concentrations of complex ranged between 12.5 and 100 microg/ml for beta-CD-econazole complex (CD-EC), while for the complex with ciclopirox-olamine (CD-CI) the range was between 150 and 400 microg/ml. The stability constants of the CD complexes with the two antimycotic derivatives are given. In addition, the nephelometric method allows the determination of solubilities of active agents. Thus, the improvement of solubility of both antimycotic agents in PBS buffer solution was observed by complexation with CD.

Permanent flame retardant finishing of textiles by allyl-functionalized polyphosphazenes.

Despite their excellent flame retardant properties, polyphosphazenes are currently not used as flame retardant agents for textile finishing, because a permanent fixation on the substrate surface has failed so far. Here, we present the successful synthesis and characterization of a noncombustible and foam-forming polyphosphazene derivative, that can be immobilized durably on cotton and different cotton/polyester blended fabrics using photoinduced grafting reactions. The flame retardant properties are improved, a higher limiting oxygen index is found, and the modified textiles pass several standardized flammability tests. As flame retardant mechanism a synergistic effect between the immobilized polyphosphazene and the textile substrate was observed. The polyphosphazene finishing induces an earlier decomposition of the material with a reduced mass loss in thermogravimetric analysis. The decomposition of cotton and polyester leads to the formation of phosphorus oxynitride, which forms a protecting barrier layer on the fiber surface. In addition, the permanence of the flame retardant finishing was proven by laundry and abrasion tests.

Inhibition of microbial pathogens by fungal chitosan.

Four fungal chitosan types (CTS) were prepared from Mucor rouxii DSM 1191 and examined for their physico-chemical characteristics. The antimicrobial activity of chitosan types against 11 bacterial strains, including six pathogens, was investigated and the most effective type was chitosan No. 3 which was characterized with the lowest viscosity and molecular weight (3.1 cP and 2.1 x 10(4)Da, respectively), the highest degree of deacetylation (95%) and neutral water solubility. Gram positive bacteria were generally more sensitive to chitosan antimicrobial action than Gram negative strains and this action was notably affected by the environmental growth conditions, i.e. incubation temperature and pH value. The applications of fungal chitosan for the suppression of bacterial pathogens as a natural alternative, reduced risk and biodegradable biocidal agent could be recommended.

Anticandidal action of fungal chitosan against Candida albicans.

The anticandidal activity of four fungal chitosan types, produced from Mucor rouxii DSM-1191, against three Candida albicans strains was determined. The most bioactive chitosan type, to inhibit C. albicans growth, had the lowest molecular weight (32 kDa) and the highest deacetylation degree (94%). Water soluble types had stronger anticandidal activity than soluble types in 1% acetic acid solution. Scanning electron micrographs of treated C. albicans with fungal chitosan proved that chitosan principally interact with yeast cell wall, causing severe swelling and asymmetric rough shapes, and subsequent cell wall lyses with the prolonging of exposure time. Fungal chitosan could be recommended for C. albicans control as a powerful and safe alternative to synthetic and chemical fungicides.

Functional group analysis on oxidized surfaces of synthetic textile polymers.

A comprehensive collection of wet-chemical analyses of functional groups on oxidatively treated surfaces of hydrophobic polymers like poly(ethylene terephthalate) or polyolefine is presented. New methods are introduced. Textiles and foils have been subjected to advanced oxidation processes and the different oxygen functions have been quantified. Analysis of surface functional groups includes radical site determination with radical scavengers like diphenylpicrylhydrazyl, reduction of peroxides determined iodometrically, cationic dyestuff adsorption, carbonyl binding to Girard reagent P and surface hydroxyl group determination by surface nitrosation and subsequent azo-dye formation photometrically determinable. Use of potential surface swelling agents has been excluded except for addition of wetting agent. Wet-chemical analyses on textile surfaces bear the benefit of integrating over (relatively) large sample areas, a point which is interesting when regarding inhomogenities of textile or other surface constructions. In addition examples for visualisation for the existence of surface groups are described.

Functionalization of catalase for a photochemical immobilization on poly(ethylene terephthalate).

The enzyme catalase (EC 1.11.1.6) was covalently immobilized on textile carrier fabrics made of poly(ethylene terephthalate) (PET) by a novel combined wet chemical and photochemical process. The functionalization of catalase with allyl groups succeeds in a wet chemical treatment of the enzyme with allylglycidylether. This modified enzyme was bonded covalently to the textile material by a photochemical immobilization using a monochromatic excimer UV lamp (222 nm). Using this two-step procedure nearly 60 mg enzyme/g carrier could be fixed durably. The efficiency of the immobilization products was investigated by measuring the enzymatic decomposition of hydrogen peroxide in comparison to the free enzyme. The relative activity of the catalase after the immobilization was nearly 5% compared to the free, not fixed enzyme; however, even after 30 reuses, the modified and immobilized catalase still showed a distinct activity.

Quantitative analysis of immobilized metalloenzymes by atomic absorption spectroscopy.

A new, sensitive assay for the quantitative determination of immobilized metal containing enzymes has been developed using atomic absorption spectroscopy (AAS). In contrast with conventionally used indirect methods the described quantitative AAS assay for metalloenzymes allows more exact analyses, because the carrier material with the enzyme is investigated directly. As an example, the validity and reliability of the method was examined by fixing the iron-containing enzyme catalase on cotton fabrics using different immobilization techniques. Sample preparation was carried out by dissolving the loaded fabrics in sulfuric acid before oxidising the residues with hydrogen peroxide. The iron concentrations were determined by flame atomic absorption spectrometry after calibration of the spectrometer with solutions of the free enzyme at different concentrations.