Y-S. Li, J. S. Church, A. L. Woodhead, F. Moussa

Iron oxide magnetic nano-particles have been prepared by precipitation in an aqueous solution of iron(II) and iron(III) chlorides under basic condition. Surface modifications have been carried out by using tetraethoxysilane (TEOS) and mercaptopropyltrimethoxysilane (MPTMS). The uncoated and coated particles have been characterized with transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, thermal gravimetric analysis (TGA), and infrared (IR) and Raman spectroscopy. The particle sizes as measured from TEM images were found to have mean diameters of 13 nm for the uncoated and about 19 nm for the coated particles. The measured IR spectra of the uncoated and MPTMS coated particles showed the conversion of magnetite to hematite at high temperature. The results obtained from both IR spectroscopy and TGA revealed that the mercaptopropylsilyl group in the MPTMS coated magnetite decomposed at 600 °C and the silica layer of the TEOS coated magnetite was rather stable. Raman spectroscopy has shown the laser heating effect through the conversion of magnetite to maghemite and hematite.

J. S. Church, A. L. Woodhead, K. Fincher

Photo-active colloidal anatase was prepared from sodium titanate nanotubes by refluxing in 0.3 M HCl. The refluxing was carried out in cycles, replacing the acid each time. After the second reflux cycle a suspension of colloidal anatase was formed above the residual solids. After three reflux cycles all of the nanotubes were converted to a residual mixture of anatase, rutile and brookite. More colloidal anatase could be isolated from this mixture through a series of water rinses. The anatase suspension was found to be made up of particles with an average diameter of 40 nm as well as a very fine 10–15 nm diameter material. This latter dimension is in line with the crystallite size determined from the anatase isolated from the suspension. At pH 1 the anatase suspension was found to be significantly more photo-active in bleaching methyl orange than P25 at exposure times up to 1.5 h. The photo-activity after 1.5 h was found to be 29% higher than the best catalyst prepared by calcining the same titanate nanotube starting material. The increased activities can probably be attributed to the increased surface area, decreased crystallite size and decreased sodium content of the anatase suspension.

J. S. Church, A. J. Poole, A. L. Woodhead

Raman spectroscopy was used to characterize films cast from dissolved feather keratin. Spectra obtained from the films were found to be very similar to those of the feather components from which they were derived. The protein structure of the films was dominated by β-sheet conformation with possibly more disordered protein content and slightly less disulfide cross-linking compared to the feather. Study of the solubilized keratin protein that the films were made from revealed that the protein conformation was more disordered and that the disulfide cross-links were largely cleaved. During the film formation process these bonds were largely reformed and the intra-chain order of the proteins increased even though the films themselves remained isotropic. The results of a polarization study revealed that upon mechanical stretching of the film, the protein chains tended to orientate towards the draw axis. The extent of orientation was found to vary randomly along the length of the stretched film suggesting domains with different properties may exist within the “as-prepared” film.

J. S. Church, K. Fincher, X. Wang

Sodium titanate nanotubes were prepared hydrothermally and sodium ions were exchanged for hydrogen ions by washing with water and further treatment with HCl. No anatase or rutile was produced during the exchange. Photo-catalysts were prepared by calcination and their activity was compared in UV-A and simulated sunlight by bleaching methyl orange,which does not adsorb onto the catalyst’s surface. Only photo-catalysts with low sodium content were capable of bleaching the dye. More photo-oxidation occurred in simulated sunlight suggesting that the dye is absorbing visible light and transferring this energy to the TiO₂. The preparation of highly active photo-catalysts from sodium titanate nanotubes may well depend on optimizing their preparation to minimize sodium content without the formation of rutile.

A. J. Poole, J. S. Church, M. G. Huson

Concerns for the environment and consumer demand are driving research into environmentally friendly fibers as replacements for part of the 38 million tonnes of synthetic fiber produced annually. While much current research focuses on cellulosic fibers, we highlight that protein fibers regenerated from waste or byproduct sources should also be considered. Feather keratin and wheat gluten may both be suitable. They are annually renewable,commercially abundant, of consistent quality, and have guaranteed supply. They contain useful amino acids for fiber making, with interchain cross-linking possible via cysteine residues or through the metal-catalyzed photocrosslinking of tyrosine residues. Previous commercially produced fibers suffered from poor wet strength. Contemporary nanoparticle and cross-linking technology has the potential to overcome this, allowing commercial production to resume. This would bring together two existing large production and processing pipelines, agricultural protein production and textile processing, to divert potential waste streams into useful products.

S. Edwards, J. S. Church, J. A. Werkmeister, J. A. M. Ramshaw

In this study we have prepared a tubular knitted scaffold from a 9 ply ultiwalled carbon nanotube (MWCNT) yarn and a composite scaffold, formed by electrospinning poly(lactic-co-glycolic acid) (PLGA) nanofibres onto the knitted scaffold. Both structures were assessed for in vitro biocompatibility with NR6 mouse fibroblast cells for up to 22 days and their suitability as tissue engineering scaffolds considered. The MWCNT yarn was found to support cell growth throughout the culture period, with fibroblasts attaching to, and proliferating on, the yarn surface. The knitted tubular scaffold contained large pores that inhibited cell spanning, leading to the formation of cell clusters on the yarn, and an uneven cell distribution on the scaffold surface. The smaller pores, created through electrospinning, were found to promote cell spanning, leading to a uniform distribution of cells on the composite scaffold surface. Evaluation of the electrical and mechanical properties of the knitted scaffold determined resistance levels of 0.9 kΩ/cm, with a breaking load and extension to break approaching 0.7 N and 8%, respectively. The PLGA/MWCNT composite scaffold presented in this work not only supports cell growth, but also has the potential to utilize the full range of electrical and mechanical properties that carbon nanotubes have to offer.

X. J. Dai, J. S. Church, M. G. Huson

A new fabric with potential in medical textiles has been developed by application of a surface coating on wool using pulsed plasma polymerization of HMDSO. This coating enabled a controllable MVTR and surface adhesion. MVTR in the range recommended for optimum wound healing was obtained by varying frequency, monomer pressure and deposition time. Lower surface adhesion was achieved. Peeling tests, contact angle measurements, SPM force curves and ATR FT-IR were used to characterize the surfaces for both wool and a PE model substrate. All these results were consistent with a decrease in surface energy after PP-HMDSO treatment. ATR FT- IR results showed a siloxane film with less organic Si–(CH₃)ₙ groups and more Si–O–Si cross-links.

J. S. Church, D. J. Evans, A. L. Woodhead

The Tasmanian devil (Sarcophilus harrisii) is the largest living marsupial carnivore left on Earth. In this paper we report the results of the first thorough characterization of the keratin fibres comprising the Tasmanian devil pelage. The fibre’s morphology, structure, composition and surface have been investigated. The results have been compared with those of a number of other mammalian species including carnivores and herbivores. The fibres structure was found to be consistent with that expected for a keratin fibre. From the results of the bound lipid analysis it can be concluded that the Tasmanian devil is a typical mammal in which the 21-carbon atom anteiso branched fatty acid is the predominant bound fatty acid. This is consistent with the Tasmanian devil’s position in the mammalian phylogenetic tree. The amino acid analysis places the devil in line with other carnivores. The high cystine and proline content may correlate with the Tasmanian devil’s diet which is rich in muscle and collagen proteins.