Richard S. Blackburn

Comparative Analysis of Crystallinity Changes in Cellulose I Polymers Using ATR-FTIR, X-ray Diffraction, and Carbohydrate-Binding Module Probes

Cotton fiber cellulose is highly crystalline and oriented; when native cellulose (cellulose I) is treated with certain alkali concentrations, intermolecular hydrogen bonds are broken and Na-cellulose I is formed. At higher alkali concentrations Na-cellulose II forms, wherein intermolecular and intramolecular hydrogen bonds are broken, ultimately resulting in cellulose II polymers. Crystallinity changes in cotton fibers were observed and assigned using attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy and X-ray diffraction (XRD) subsequent to sodium hydroxide treatment and compared with an in situ protein-binding methodology using cellulose-directed carbohydrate-binding modules (CBMs). Crystallinity changes observed using CBM probes for crystalline cellulose (CBM2a, CBM3a) and amorphous cellulose (CBM4-1, CBM17) displayed close agreement with changes in crystallinity observed with ATR-FTIR techniques, but it is notable that crystallinity changes observed with CBMs are observed at lower NaOH concentrations (2.0 mol dm(-3)), indicating these probes may be more sensitive in detecting crystallinity changes than those calculated using FTIR indices. It was observed that the concentration of NaOH at which crystallinity changes occur as analyzed using the CBM labeling techniques are also lower than those observed using X-ray diffraction techniques. Analysis of crystallinity changes in cellulose using CBMs offers a new and advantageous method of qualitative and quantitative assessment of changes to the structure of cellulose that occur with sodium hydroxide treatment.

In situ analysis of cell wall polymers associated with phloem fibre cells in stems of hemp, Cannabis sativa L.

A study of stem anatomy and the sclerenchyma fibre cells associated with the phloem tissues of hemp (Cannabis sativa L.) plants is of interest for both understanding the formation of secondary cell walls and for the enhancement of fibre utility as industrial fibres and textiles. Using a range of molecular probes for cell wall polysaccharides we have surveyed the presence of cell wall components in stems of hemp in conjunction with an anatomical survey of stem and phloem fibre development. The only polysaccharide detected to occur abundantly throughout the secondary cell walls of phloem fibres was cellulose. Pectic homogalacturonan epitopes were detected in the primary cell walls/intercellular matrices between the phloem fibres although these epitopes were present at a lower level than in the surrounding parenchyma cell walls. Arabinogalactan-protein glycan epitopes displayed a diversity of occurrence in relation to fibre development and the JIM14 epitope was specific to fibre cells, binding to the inner surface of secondary cell walls, throughout development. Xylan epitopes were found to be present in the fibre cells (and xylem secondary cell walls) and absent from adjacent parenchyma cell walls. Analysis of xylan occurrence in the phloem fibre cells of hemp and flax indicated that xylan epitopes were restricted to the primary cell walls of fibre cells and were not present in the secondary cell walls of these cells.

A greener approach to cotton dyeings with excellent wash fastness

Attempts were made to find a more environmentally friendly method of dyeing cotton as an alternative to standard reactive dyeing processes that require high levels of water, salt and alkali and produce high levels of effluent contamination. It was intended that the new method would not compromise the excellent wash fastness levels typical of reactive dyed cotton. By employing a pre-treatment method, salt and alkali could be completely eliminated from the dyeing process and, in comparison with standard reactive dyeing processes, the time taken for the dyeing process to be completed could be significantly reduced and the volume of water required could be halved. The dyeings secured using the pre-treatment method had wash fastness values equal to those observed for the standard reactive dyeings.

Monoclonal Antibodies Directed to Fucoidan Preparations from Brown Algae

Cell walls of the brown algae contain a diverse range of polysaccharides with useful bioactivities. The precise structures of the sulfated fucan/fucoidan group of polysaccharides and their roles in generating cell wall architectures and cell properties are not known in detail. Four rat monoclonal antibodies, BAM1 to BAM4, directed to sulfated fucan preparations, have been generated and used to dissect the heterogeneity of brown algal cell wall polysaccharides. BAM1 and BAM4, respectively, bind to a non-sulfated epitope and a sulfated epitope present in the sulfated fucan preparations. BAM2 and BAM3 identified additional distinct epitopes present in the fucoidan preparations. All four epitopes, not yet fully characterised, occur widely within the major brown algal taxonomic groups and show divergent distribution patterns in tissues. The analysis of cell wall extractions and fluorescence imaging reveal differences in the occurrence of the BAM1 to BAM4 epitopes in various tissues of Fucus vesiculosus. In Ectocarpus subulatus, a species closely related to the brown algal model Ectocarpus siliculosus, the BAM4 sulfated epitope was modulated in relation to salinity levels. This new set of monoclonal antibodies will be useful for the dissection of the highly complex and yet poorly resolved sulfated polysaccharides in the brown algae in relation to their ecological and economic significance.

Optimizing the Colour and Fabric of Targets for the Control of the Tsetse Fly Glossina fuscipes fuscipes

Background Most cases of human African trypanosomiasis (HAT) start with a bite from one of the subspecies of Glossina fuscipes. Tsetse use a range of olfactory and visual stimuli to locate their hosts and this response can be exploited to lure tsetse to insecticide-treated targets thereby reducing transmission. To provide a rational basis for cost-effective designs of target, we undertook studies to identify the optimal target colour. Methodology/Principal Findings On the Chamaunga islands of Lake Victoria , Kenya, studies were made of the numbers of G. fuscipes fuscipes attracted to targets consisting of a panel (25 cm square) of various coloured fabrics flanked by a panel (also 25 cm square) of fine black netting. Both panels were covered with an electrocuting grid to catch tsetse as they contacted the target. The reflectances of the 37 different-coloured cloth panels utilised in the study were measured spectrophotometrically. Catch was positively correlated with percentage reflectance at the blue (460 nm) wavelength and negatively correlated with reflectance at UV (360 nm) and green (520 nm) wavelengths. The best target was subjectively blue, with percentage reflectances of 3%, 29%, and 20% at 360 nm, 460 nm and 520 nm respectively. The worst target was also, subjectively, blue, but with high reflectances at UV (35% reflectance at 360 nm) wavelengths as well as blue (36% reflectance at 460 nm); the best low UV-reflecting blue caught 3× more tsetse than the high UV-reflecting blue. Conclusions/Significance Insecticide-treated targets to control G. f. fuscipes should be blue with low reflectance in both the UV and green bands of the spectrum. Targets that are subjectively blue will perform poorly if they also reflect UV strongly. The selection of fabrics for targets should be guided by spectral analysis of the cloth across both the spectrum visible to humans and the UV region.

The Combined Synthesis and Coloration of Poly(lactic acid)

With the continuing depletion of petrochemical feedstocks, it has become necessary to produce new, useful, and environmentally friendly polymers for a sustainable future. Synthesis of a polyester from lactic acid was pioneered by Carothers in 1932 and developed by DuPont. Poly(lactic acid) (PLA) is a linear aliphatic thermoplastic polyester derived from 100 % renewable sources, and the polymer is compostable. The production of PLA uses 20–50% less fossil fuel resources than comparable petroleum-based fibers. PLA is a particularly “green” polymer in terms of sustainability and degradation, two vital components of the cradle-to-grave life cycle. Plants process atmospheric CO2 and water through photosynthesis to make the raw materials from which the building blocks of PLA can be obtained; and composting converts PLA into CO2, water, biomass, humus, and other natural substances (Figure 1). PLA is formed either by direct condensation of lactic acid, or, most effectively, via the cyclic intermediate dimer (lactide) through a catalyzed ring-opening polymerization (ROP) process. Metal alkoxides are the most common catalysts employed in ROP of cyclic esters. Aluminum alkoxides have been shown to give a controlled and living polymerization of lactides through a socalled coordination/insertion mechanism. For a typical textile dyeing process, poly(ethylene terephthalate) and PLA (Figure 1) are initially scoured with detergent and alkali to remove hydrophobic auxiliaries (aids knitting and weaving), and then dyed with disperse dyes in an aqueous dyebath buffered to pH 4.5 using sodium acetate or acetic acid at 130 8C or 115 8C, respectively. To achieve acceptable wash fastness properties (ability of dye to adhere to material), “after-clearing” with reducing agents is employed to remove the excess dye. Reduction after-clearing has a significant detrimental environmental impact because of the strong alkaline conditions, large amounts of water used, and the discharge of high levels of sulfur with the wastewater. 11] There is also concern that effluent from disperse dyeing operations of the reduction after-clearing process contains by-products, particularly aromatic amines from the reduction of azo dyes, that have mutagenic and carcinogenic activity. 13] Herein we report the use of a catalyst containing a chromophore, which will simultaneously carry out the polymerization, and in addition, incorporate the dye, needed to color the material, into the polymer backbone itself—termed the DyeCat process. Thus, the coloration process can achieve high color strength without exposing the fiber to potentially damaging conditions; these are two essential prerequisites for future commercial applications of PLA. As shown in Figure 1, the wet processing stages (preparation, dyeing, finishing) are not required for DyeCat PLA because coloration is achieved through the polymerization process. Hence the consumption of energy, water, chemicals, and time, as well as effluent production are all avoided. Residual catalyst in the polymers can lead to undesirable polymer properties, including discoloration, and removal of the spent catalyst from a polymer is often difficult and Figure 1. Life cycle of PLA for textile applications (Figure adapted from Gross and Kalra).

A greener approach to cotton dyeings. Part 2: application of 1∶2 metal complex acid dyes

Further attempts were made to find a more environmentally friendly method of dyeing cotton as an alternative to standard reactive dyeing processes that require high levels of water, salt and alkali and produce high levels of effluent contamination.Pre-treatment with a polymeric cationic quaternary ammonium compound enabled dyeing of the fibre with 1∶2 (M∶L) metal complex acid dyes without salt at neutral/slightly acidic pH values. In comparison with standard reactive dyeing processes, both the time taken for the dyeing process to be completed and the volume of water required could be dramatically reduced. The dyeings secured using the pre-treatment method displayed high colour strength values, good to very good wash fastness and excellent light fastness.

Carbon Black Reinforced Epoxy Resin Nanocomposites as Bending Sensors

By blending electrically conducting carbon black particles and silica into poly(bisphenol A-co-epichlorohydrin) epoxy resin polymer, conductive nanocomposites were prepared by printing onto transparency films and curing. Application of a milling procedure prior to application is beneficial for the reduction of cracks in the subsequent nanocomposites. Electrical conduction of nanocomposite is CB content dependent. A percolation region (19—24% CB on mass of resin) exists where the nanocomposite exhibits a transition from an electrical insulator to conductor. Nanocomposites with 14% and 19% CB on mass of resin demonstrated greatest sensitivity to changes in bending angle, attributed to greater localized changes in the conductive paths within a semi-conducting sensor. Good reproducibility was observed as a result of molecular interactions between CB particles and the epoxy resin.

Mild extraction methods using aqueous glucose solution for the analysis of natural dyes in textile artefacts dyed with Dyer’s madder (Rubia tinctorum L.)

Madder (Rubia tinctorum L.) has been widely used as a red dye throughout history. Acid-sensitive colorants present in madder, such as glycosides (lucidin primeveroside, ruberythric acid, galiosin) and sensitive aglycons (lucidin), are degraded in the textile back extraction process; in previous literature these sensitive molecules are either absent or present in only low concentrations due to the use of acid in typical textile back extraction processes. Anthraquinone aglycons alizarin and purpurin are usually identified in analysis following harsh back extraction methods, such those using solvent mixtures with concentrated hydrochloric acid at high temperatures. Use of softer extraction techniques potentially allows for dye components present in madder to be extracted without degradation, which can potentially provide more information about the original dye profile, which varies significantly between madder varieties, species and dyeing technique. Herein, a softer extraction method involving aqueous glucose solution was developed and compared to other back extraction techniques on wool dyed with root extract from different varieties of Rubia tinctorum. Efficiencies of the extraction methods were analysed by HPLC coupled with diode array detection. Acidic literature methods were evaluated and they generally caused hydrolysis and degradation of the dye components, with alizarin, lucidin, and purpurin being the main compounds extracted. In contrast, extraction in aqueous glucose solution provides a highly effective method for extraction of madder dyed wool and is shown to efficiently extract lucidin primeveroside and ruberythric acid without causing hydrolysis and also extract aglycons that are present due to hydrolysis during processing of the plant material. Glucose solution is a favourable extraction medium due to its ability to form extensive hydrogen bonding with glycosides present in madder, and displace them from the fibre. This new glucose method offers an efficient process that preserves these sensitive molecules and is a step-change in analysis of madder dyed textiles as it can provide further information about historical dye preparation and dyeing processes that current methods cannot. The method also efficiently extracts glycosides in artificially aged samples, making it applicable for museum textile artefacts.

Isolation and extraction of lucidin primeveroside from Rubia tinctorum L. and crystal structure elucidation

Madder (Rubia tinctorum L.) has been used as a dye for over 2000 years with alizarin and purpurin the major natural dyes analysed from extractions undertaken. The use of ethanol as the solvent in the extraction process produced an extract that yielded four anthraquinone compounds lucidin primeveroside, ruberythric acid, alizarin and lucidin-ω-ethyl ether. Gravitational separation of the extract was used to record the first crystal structure of lucidin primeveroside, which is also the first ever known crystal structure of a glycoside containing anthraquinone moiety. The crystal structure along with (1)H and (13)C NMR helped elucidate and confirm the structure of this overlooked natural dye which has been shown to be a major compound in R. tinctorum L.