Application of nanotechnology for wool and wool blends in medical textiles utilising biopolymers

The object of this research was to explore ways to utilise wool in medical textiles particularly in wound-dressing materials. Wool was chosen for this study as it possesses the highest moisture regain property (saturation regain is approximately 36%) among all the natural and synthetic polymers. The experimental sets were designed to highlight two major fields for wound-dressings namely the use of nonwovens and films. A biopolymer chitosan (CHT) and silver nanoparticles were chosen for their antibacterial properties to be applied to wool and wool-blend materials to assess their potential use in wound-dressing materials. Three different routes of processing were chosen for the current research namely are: pad-dry-cure, electrospraying and dissolution and regeneration of polymers to prepare blend films. For this study, 100% wool nonwoven and wool–viscose (50-50) nonwovens, having weight of 150–400 grams per square metre (GSM) were prepared and post-treated with a range of CHT concentrations varying from 0.1–1.0% on the weight of material. 0.3% CHT-treated samples were found to be optimally absorbent together with excellent anti-bacterial properties. The current study also explored the method of electrospraying of chitosan to coat wool nonwoven substrates, a technique that has been introduced for the very first time. Scanning electron micrographs of the coated 100% wool nonwoven (400 GSM) showed excellent coatings with 0.3% CHT (OWM). The coated substrates were also tested for anti-bacterial properties and proved to be outstanding. Thus this novel technique provided excellent coating opportunities for textiles to achieve suitable substrates with enhanced functional properties. Both CHT and wool are renewable, bio-degradable and bio-compatible, but are complicated to process by directly dissolving in common solvents. A new class of ionic liquid solvent 1-butyl, 3-methyl imidazolium chloride (BMIMCl) has provided an ideal platform to solubilise polymers to achieve the blending operation. The current study blended wool and chitosan utilising BMIMCl as their common solvent and characterised the resultant films. It was shown that wool-CHT (50-50) blend films were homogeneous and exhibited excellent anti-bacterial attributes. Silver nanoparticles (SNPs) were also incorporated into the films by utilising the BMIMCl wool dissolution technique. The 100% films prepared from BMIMCl dissolution and regeneration containing 0.5% (OWM) SNPs proved to possess antibacterial features. Since toxicological behaviour and potential health concern of using SNPs are yet to be comprehensively understood, wool-CHT films are recommended because of non-toxicity, biodegradability and are effective at low concentrations.