S. Aljohani, J.H Johnston
Victoria University of Wellington,
Keywords: wool, textiles, antimicrobial, methylglyoxal, manuka honey, composite
Summary:Wool textile products are widely used in apparel, furnishings and floor coverings. They also find use in medical, and healthcare applications such as bandages and masks where unfortunately they can provide environment favourable for microbial contamination mainly due to the large surface area of the fibres and their ability to retain moisture. The microorganisms’ growth on textile surfaces increases the potential risk of infection, cross-infection, and transmission of diseases. As such, there is an increasing demand for hygienic textile materials which have been functionalised with particular agents to impart antimicrobial properties to them. A number of studies of such antimicrobial fibre composites have reported for synthetic fibres and textiles, and to a lesser extent for natural fibres, notably cotton. Professor Johnston’s research group at Victoria University of Wellington has successfully functionalized wool textile fabrics with nanogold as a novel colourant for the high value apparel and rug markets, and with nanosilver for antimicrobial apparel, furnishing fabrics and carpets. The resulting nanosilver-wool fibres exhibit high antimicrobial activity against Staphylococcus aureus and Escherichia coli microbes. There is a parallel interest in capturing the antimicrobial properties of naturally occurring chemical compounds by incorporating them into textiles. In this paper we present the novel use of New Zealand Manuka honey and particularly the active ingredient methylglyoxal (MGO) as a natural antimicrobial agent in wool fibres and textiles. New Zealand Manuka honey (MH) is well known for its natural antibacterial medicinal properties which can be collectively attributed to the high level of sugar, moderately low pH, and the presence of hydrogen peroxide, and non-peroxide compounds. MGO has been identified as a non-peroxide antibacterial compound in this honey, which has been linked to its sought after and effective antimicrobial activity. We have innovatively incorporated MH and also MGO into wool fibres in loose top form, yarn and in finished fabrics. The extent of uptake of MH and MGO from solution at different temperatures and concentrations has been characterised by High-Performance Liquid Chromatography. The nature of the MH-wool and MGO-wool composites have been characterised by FTIR spectroscopy, Differential Scanning Calorimetry and Thermogravimetric Analysis. This suggests the MH and MGO entities are attracted and weakly chemically bound to the fibre surface, probably through van der Waals forces, and also diffuse into the fibres between the cuticles on the surface. The absorption and diffusion rate of MGO into a fibre are highly dependent on the initial MGO concentration, temperature and diffusivity. The maximum amounts of MH and MGO that were incorporated unto the wool fibres were 1.54 and 2.98 wt% respectively. In addition, MGO-Wool composite was treated with the hydrophobic surface agent Dynasylan® (F8815), which increased the water droplet contact angle and hence the hydrophobicity of the woollen fabric. The methodology and results of this innovative development of a wool composite with the natural antimicrobial agent methylglyoxal as itself or as a component of Manuka honey will be presented. Possible applications include antimicrobial apparel and medical textiles and bandages.