Synergistic Analytical Investigations of the Chemical and Structural Properties of Keratin Fibres

Abstract

Abstract Keratin fibres are biomaterials which have a high degree of complexity. When analysing their properties, a two-phase structure is applied, where the components are highly ordered, semi-crystalline intermediate filaments (IFs) embedded in an amorphous matrix. Fourier transform infrared spectroscopy (FTIR) is an analytical method which is widely used in the field of textiles and cosmetic science to obtain knowledge about damage and changes to proteins in the keratin fibres. Milling is a mechanical pre-treatment which is used to obtain powders for, e.g., Transmission-FTIR or other analytical methods. However this process causes thermal damage and physical changes to the proteins and their structure through attrition. Methods to enable us in the determination of the limiting conditions of milling was analysed in this research, optimal conditions with minimum damage to the proteins in the fibres as well as their secondary structures such as the α-helices. DSC results showed that with 25 Hz milling with liquid nitrogen pre-cooling, discontinuously, for up to 40 seconds, there was invariance in results for denaturation temperature (TD) and denaturation enthalpy (ΔHD). This invariance demonstrates that the viscosity of the matrix remains largely unchanged, kinetically impeding the unfolding of IFs to a similar extent as the matrix in reference samples. There was a destabilisation of the IFs for longer treatment times. A lower limiting value of around 133 °C was obtained for the data sets for milled fibres at 60 s, which is associated with the properties of the keratin fibre becoming an increasingly amorphous, highly-crosslinked, thermoset polymer. SDS-PAGE protein analysis shown there was no difference in result to that of the reference sample between all milling conditions and times. Spectral analysis of the Amide I was carried out to provide information of the secondary structures (α-helix, β-sheets, turns and unordered) of the proteins; where there was no change with milling times or conditions. This was an unexpected result as DSC data showed that the proteins, especially that of the IFs, were close to complete denaturation. This variance in results can be explained by the term ‘latent damage’. Dynamic mechanical properties were observed by the use of a novel sample powder holder to obtain glass transition temperatures (Tg). The results gave a Tg for dry merino wool with the use of glycerol as an inert diluent. Measuring the glass transition as a material compared to historical methods. Advances have been made in a technique to determine the orientation of the intermediate filaments in the cortical cells of keratin fibres. The main objective was to determine if the IFs are aligned in a parallel or anti-parallel manner. Experimental methods were developed where an electric field was produced and was applied to single cortical cells, which were obtained through the process of enzymatic digestion using trypsin. The cells were placed in a media (water) and movement of the cells was observed. The result show movement of the cells, the methodology requires more work and improvements, but this would be a feasible method to answer this question in the future.

Date of Award	1 Aug 2019
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Franz Wortmann (Supervisor) & Gabriele Wortmann (Supervisor)