Effect of water at elevated temperatures on the wool fibre surface

Oxidative Modification of Trichocyte Keratins

Oxidation of keratin results in a range of deleterious effects, including discolouration and compromised physical and mechanical properties. Keratin oxidative degradation is driven by molecular-level events, with accumulation of modifications at the protein primary level resulting directly in changes to secondary, tertiary and quaternary structure, as well as eventually changes in the observable physical and chemical properties. Advances in proteomic analysis techniques provide an increasingly clearer insight into the cascade of molecular modification underpinning keratin oxidation and how this translates through to higher order changes in properties. This chapter summarises the effects of oxidation on keratin-based materials, the types of molecular modification associated with this, and advances in techniques and approaches for characterising this modification.

Proteomic characterisation of hydrothermal redox damage

BACKGROUND

Peptide and protein damage contributes to the loss of quality and value in protein-based food and textile products as well as to the degeneration of biological tissues such as hair and skin. The effects of elevated temperature on such substrates at the molecular level are, however, relatively unknown. This paper examines the response of peptides and proteins to hydrothermal damage using mass spectrometry and reports the location of molecular markers of hydrothermal damage within wool proteins.

RESULTS

The hydrothermal exposure of model peptides containing the oxidatively sensitive residues tryptophan and tyrosine revealed the formation of a number of products such as hydroxytryptophan and dihydrophenylalanine. A variety of degradation products were also observed in intermediate filament proteins, including products arising from deamidation and from oxidation of histidine, tyrosine and tryptophan residues.

CONCLUSION

The products observed to form during hydrothermal exposure indicated the involvement of reactive oxygen species. Molecular markers were identified within a proteinaceous system to allow the evaluation of damage type or severity. These findings have important implications for the thermal processing of foods and textiles.

Application of anisotropic silver nanoparticles: multifunctionalization of wool fabric

Anisotropic silver nanoparticles (NPs) were successfully employed to color the wool fabrics in this study. The modified wool fabrics exhibited brilliant colors due to the localized surface plasmon resonance (LSPR) properties of silver NPs. The colors of wool fabrics altered with the morphologies of silver NPs. These modified wool fabrics were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results indicated that anisotropic silver NPs were effectively assembled on the surface of wool fibers when the solution pH and temperature was about 4 and 40°C, respectively. This assembling of silver NPs on the wool fibers was realized by the electrostatic interaction between wool fibers and silver NPs. This technique was also applied to gold NPs. The fabrics treated with anisotropic silver NPs showed high antibacterial activity against the bacteria of Escherichia coli. This study opens a new approach to color and functionalize conventional textile materials.

Atomic force microscopy of human hair

The atomic force microscope (AFM) was used to investigate the surface architecture of the entire lengths of cleaned human head hairs. Many features previously seen with the scanning electron microscope (SEM) were identified. However, the AFM has provided much greater detail and, in particular, the hair's cuticular surfaces appear not to be as smooth as had been previously supposed. A consistent feature was of step discontinuities or "ghosts" on the scale surfaces. These delineated the original location of each overlying scale before its edge had been chipped away. There was a change in the longitudinal angular presentation of the surfaces about each ghost. This means the distal ends of each cuticle cell have been synthesised in the follicle to be thicker than where that same cuticle cell is bounded on both sides by other cuticle cells. The undamaged outer cuticular surfaces at the root end of each hair were covered everywhere by longitudinal ridges (striations). Where the hair surface was worn, the striations terminated at a scale edge ghost. The ridges were approximately 9 nm high and were in parallel array with a lateral repeat spacing of about 350 nm. The striations are evidently formed on the outer surface of each cuticle cell following earlier contact in the hair follicle with the inner root sheath. The study of stained transverse sections of hairs in the transmission electron microscope (TEM) is suggested as a means for throwing some light on the underlying structure and chemistry of the striations. Finally, our AFM studies have revealed that the surface of the freshly emergent hair gradually changes over a distance of about 20 mm and that the surface of the hair for most of its length is quite different from that near the root. This is likely to be of import to those engaged in the hair toiletries industry.