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There has been a significant increase in children’s burns in the past several years and figures indicate that children suffer more burns compared to any other age groups. The main concern following a burn is the possibility of infections. The aim of this project is to construct a unique wound dressing, which enhances healing and stimulates wound closure by incorporation of collagen, as well as signalling the presence of pathogenic bacteria on colonisation. The process of signalling bacterial colonisation was achieved by incorporation of a phospholipid based nanocapsule, with a colourimetric response and a mechanism for release of a dye. This research invested into finding the optimum phospholipid composition to obtain a stable and sensitive system. The signalling device uses the biomimetic aspect of vesicles to signal the presence of pathogenic bacteria via the effect of secreted toxins on the sensor interface. The modified phospholipid based sensors were immobilised into gel matrices and further developed to produce prototype dressings. The healing enhancing property was achieved by a thin layer of collagen coating. This work presents the results obtained from the initial modification process of the sensor, to incorporation of the vesicles into gel matrices through to development of First and Second Generation Prototype dressings. Verification of stability and sensitivity of the vesicles was carried out following each stage of development, using clinically isolated strains of pathogenic bacteria. Initial cytotoxicity and verification of the wound healing property was achieved by in vitro cell assays.

Nonwoven materials are widely used in medical and hygiene applications, and may demonstrate significant anisotropic characteristics in liquid transport. This study investigates the anisotropic liquid transport in such structures, and establishes a relationship between the structure and anisotropic properties of liquid transport. A comprehensive literature review is concerned with previous work on liquid transport in general with particular reference to its importance in the function of wound dressings. Preliminary experiments using commercial nonwoven wound dressing fabrics demonstrated the anisotropic nature of liquid absorption. After a review of existing steady state and dynamic methods of measuring the liquid transport in fabrics, a novel computer-integrated instrument is described that measures the in-plane liquid transmission in up to eight different directions. Needle-punched and hydroentangled fabrics with different structural parameters (fibre type, fibre diameter, fabric porosity and fibre orientation) were produced and characterised. The anisotropic liquid transport properties of these fabrics were tested using the new instrument. Unique theoretical models were established to predict the specific directional permeability of nonwoven fabrics based on the main fabric structural parameters (fibre diameter, fabric porosity and fibre orientation distribution).

The use of amniotic membrane (AM) as a dressing for ocular surface injuries has attracted the interest of the military ophthalmological community. First applied in the 1930s, the tissue is widely used today, although clinical indications for treatment are incompletely defined. While AM is most commonly stored frozen and thawed before use, dried AM is preferred for logistical reasons. Optimal preservation of the tissue is necessary to preserve its quality. The effect of drying on the physical and biological properties of the tissue are unknown. A systematic review of the evidence of AM treatment of acute chemical injuries was conducted. A framework was proposed for optimising the dried tissue through thermal, moisture sorption and surface analytical techniques. The physical properties of AM preparations were compared by mechanical testing and mathematical modelling, and an attempt was made to cross-link the AM collagen. Inflammatory aspects of the tissue were assessed by immunological techniques, zymography and macrophage assays. There is a lack of high quality evidence to support the clinical application of AM for acute burns. Complex interactions were demonstrated between the dried tissue, its excipients and moisture, suggesting novel ways of optimising the product. The mechanical properties of the dried membrane indicated that the process adversely affected the tissue, and artificial cross-linking could not be achieved. While the presence of antimicrobial peptides was not clearly established, the elution of collagenolytic enzymes was shown in therapeutic preparations of AM. The production of tumour necrosis factor by macrophages, which adhere to the spongy layer of AM, was suppressed. This project makes original contributions relevant to the use of dried AM as a biomaterial in ophthalmic surgery. Further refinements of this work, animal model experimentation and clinical trials may support its future acceptance as a clinical application.