Bioactive glass microspheres with controlled drug fluting capabilities for use in synthetic skin scaffolds

Abstract

Chronic skin wounds are a significant health condition caused by a wide range of factors. In Australia, it is estimated that over 200,000 people each year suffer from a chronic skin wound condition costing up to $285 million annually in treatments. Currently, severe cases of chronic skin wounds are treated using skin grafts and tissue engineered skin constructs. These devices are expensive and are unable to prevent infections. Without proper monitoring and replacement, these grafts and constructs can act as reservoir for pathogens to proliferate protected from the patient’s immune system. Infected wounds are often polymicrobial and the microbes able to produce biofilm which acts as a barrier between the microbe and antibiotic molecules. Currently, research is focused on the development of synthetic scaffolds with antimicrobial capabilities. Scaffolds created by other researchers either focuses on biocompatibility and mimicking of the extracellular matrix or delivery of drugs in a sustained release. Rarely both are combined due to problems of maintaining sustained drug release lasting the entire wound healing period. A two-part device consisting of a biocompatible biodegradable scaffold and bioactive glass microspheres to act as a delivery vector for antibiotics has been proposed in this thesis. This thesis will explore the methods of producing bioactive glass microspheres of various forms, attachment of the microspheres to the scaffold in a non-destructive method and the drug loading and release profile of the device when combined together. Results from this thesis show that wholly formed and hollow microspheres can be produced using a flame spray technique. Attachment of these microspheres to the scaffolds can be achieved by taking advantage of the low glass transition phase of the scaffold material while minimising scaffold damage. Microspheres attached using these methods are mechanically stable. Drug released from microspheres attached to the scaffold are significant but not sustained. In conclusion, a two-part wound healing device can be used to treat infected chronic wounds.