Development of an Electrospun Antimicrobial Mesh for Enzymatically-Controlled Release of Reactive Oxygen Species for Wound Healing

Abstract

Wound infections remain a significant concern due to the emergence of antibiotic-resistant bacteria, demanding the development of novel therapies. Traditional wound treatments have utilised the antimicrobial properties of honey, which are a result of its enzymatically generated hydrogen peroxide (H2O2), a type of reactive oxygen species (ROS). However, delivering honey's active ingredients to the wound site in a controlled and sustained manner has proven challenging. This project aims to use electrospinning to encapsulate RO-101®, a wound gel that releases enzymatically-regulated H2O2, into polymeric sub-micron fibres, ultimately producing a dressing capable of generating therapeutic levels of H2O2 by harnessing wound exudate. The resulting dressing will act as a barrier against infections, support the healing process, and create a favourable environment for cell growth. Polyvinyl alcohol (PVA) was used as the carrier for RO-101, and the incorporation of the gel into the fibres was confirmed using nuclear magnetic resonance (NMR) or Fourier-transform infrared (FTIR) spectroscopy. Morphological studies revealed smooth fibres with diameters in the range of 300-500 nm that could mimic the extracellular matrix (ECM). PVA/RO-101 meshes exhibited water contact angles as low as 30° and swelling percentages close to 200% of their mass. These three-dimensional meshes were capable of generating H2O2 in concentrations up to 20 mM/mL/g after 24 hours of activation in water and sustaining release for 72 hours. Physicochemical stability in aqueous environments was achieved through chemical crosslinking or the incorporation of a hydrophilic polymer, polycaprolactone (PCL), via coaxial and dual electrospinning. Gelatin was also added to enhance cell adhesion. RO-101-containing meshes exhibited antimicrobial activity against Gram-positive and Gram-negative bacteria, including multidrug-resistant organisms such as methicillin-resistant Staphylococcus aureus, and disrupted biofilm formation. These meshes also supported the attachment and proliferation of human adipose-derived stem cells and human dermal fibroblasts. This is the first time an antimicrobial gel has been successfully encapsulated into sub-micron fibres and validated for H2O2 release, even after gamma sterilization. The techniques and materials proposed in this thesis represents a significant step forward in the development and manufacturing of the next generation of wound dressings.

Date of Award	1 Aug 2024
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Paul Mativenga (Supervisor) & Gavin Humphreys (Supervisor)