Modification of Fibers with Nanostructures Using Reactive Dye Chemistry.

Reactive dyes conventionally used to chemically bind chromophores to fabrics have been used to develop a platform technology that can modify commercially available fibers with nanoscale structures. To illustrate this concept, commercial nylon and cellulose fibers have been modified with gold nanoparticles of three sizes, metal organic framework (MOF) crystals, and quantum dots in five sizes. The gold modified cellulose and nylon samples have colors that vary based on the size of the gold particles, and the particles remained attached to the fibers, even after being washed with solvents, water, and soap. The MOF was grown on the fibers after applying reactive dyes to anchor the metal building unit to the fibers, and the process produced cellulose fibers with surface areas of ~980 m2/g. Both the nylon and cellulose MOF modified fabrics show preferential adsorption of ethylene over ethane and the ability to adsorb ammonia from air. Quantum dot modified nylon and cellulose fibers have fluorescent properties consistent with the unbound particles and remained attached to the fibers after washing with organic solvents, water, and soap. Applications are broad, and this work provides a first step at coupling conventional dyes and nanotechnology.

Selected chloro and bromo derivatives of triclosan--syntheses and their occurrence in Canadian sewage and biosolid samples.

The occurrence of triclosan (TCS), a general purpose antibacterial agent contained in numerous consumer and personal-care products, in the aquatic environment is well known. To a lesser degree, the formation of chlorinated and brominated derivatives of TCS during the chlorination of the antibacterial has also been reported. Presumably due to the lack of authentic standards, very few reports have been published on the levels of these halogenated TCSs in the environment. For this purpose, we have synthesized six selected halogenated derivatives of TCS, namely, 3-Cl-, 5-Cl-, 3,5-Cl2-, 3-Br-, 5-Br-, and 3,5-Br2- TCSs, with supporting (1)H-NMR (nuclear magnetic resonance) and GC-MS (gas chromatography-mass spectrometry) data for their structural assignments. Using these model compounds together with sensitive analytical methods, we were able to identify and quantify the above compounds together with their precursor compound TCS in Canadian municipal wastewater and biosolid samples for the first time. While detected in all influent (range from 1.4 to 24.1 ng L(-1)) and biosolid (range from 7.7 to 274 ng g(-1)) samples, the concentrations of these chlorinated TCS were generally from 100- to 1,000-fold lower than TCS in the same sample. Even lower levels (<20 ng/g in 85% of the results) of brominated TCS were found in biosolids, and they were mostly undetected in sewage.

Comparative toxicity of a brominated flame retardant (tetrabromobisphenol A) on microalgae with single and multi-species bioassays.

The potential threat of emerging chemicals to the aquatic flora is a major issue. The purpose of the study was to develop a multispecies microalgae test in order to determine the impact of species interactions on the cytoxicity of an emergent toxic contaminant: the tetrabromobisphenol A (TBBPA). Single and multi-species tests were thus performed to study the effects of this flame retardant on two microalgae (Pseudokirchneriella subcapitata and Nitzschia palea) commonly observed in freshwater. A synthetic medium was designed to allow the growth of both species. The algae were exposed to 1.8, 4.8, 9.2, 12.9 and 16.5 µM of TBBPA for 72 h. After staining with fluorescein diacetate (FDA), viable cells of each alga species were analyzed by flow cytometry based on chlorophyll autofluorescence and intracellular esterase activity. Density and abundance of viable cells were assessed to follow the population growth and the cell viability. In TBBPA treated samples, the growth of the two microalgae was significantly inhibited at the three highest concentrations (9.2, 12.9 and 16.5 µM) in the two tests. At the end of the experiment (t=72 h), the cell viability was also significantly smaller at these concentrations. The decreases of growth rate and viable cell abundance in TBBPA treated populations of N. palea were significantly higher in multi-species test in comparison with the single-species test. No significant differences were noticed between the two tests for P. subcapitata populations exposed to TBBPA.