oa The development of analytical measurements for point of care testing in chronic wound healing

In recent years a specialist interest has developed worldwide in Advanced Wound Management for difficult to heal chronic wounds. This is timely given the increasing number of elderly in the population and the growing burden of diabetes, obesity and cardiovascular disease that all contribute to an increase in hard to heal wounds. Further progress in Advanced Wound Management will require an improvement in personalised medicine for the patient and in particular an improvement in the availability of diagnostic tests and parameters that fulfil clinical need in wound management decisions. At the current time in wound care there is little available in near patient testing for clinical diagnostics. This research project focuses on a number of metrics for wound condition and wound healing: wound moisture, wound fluid pH, and wound matrix metalloproteinases (MMP) enzyme activity. To observe these important markers a state of the art sensor for wound moisture monitor is being deployed in clinical studies and new sensors are currently in development for both pH and MMP-9 enzyme level. Moisture levels in wounds can determine how well a wound heals and in addition it is possible to make decisions on the need for dressing changes based upon moisture readings taken from inside the dressing. The pH of a wound can affect many different phases of the healing process such as oxygen levels, cell proliferation, protease enzyme activity and bacterial growth. If the pH level of a wound can be effectively monitored then it can act as a biological marker to aid in diagnostics and in establishing the optimum conditions for healing. The pH electrode has not been successfully adapted into smaller and alternate packaging because the membrane that forms the selective part of the electrode, being made of silicon glass, is fragile, thus limiting manufacture, sterilisation and practical application. A disposable sensor has been produced through a screen printing method with an ion-selective membrane. The sensor is able to detect the pH in an operational range in the pH 3.5-10 with as little 10µL of fluid. MMPs are involved in every phase of wound healing. If the balance of the MMPs is upset within a wound it can upset the cellular processes preventing healing and eventually causing further damage to the wound. In chronic wounds the amount of MMP-9 activity has been found to be 30 times more than in acute wounds. By measuring the MMP-9 level of a wound the clinician will be able to choose treatment appropriately to return the MMP level to optimum healing conditions. The project has developed an assay for measuring MMP-9 at physiologically relevant levels between 0.01-100ng/ml. These sensors will enable the wound healing markers of moisture, pH and MMP enzyme activity to be studied and profiled in Hamad Medical Corporation which will further the understanding of these markers and their relationship in the complex healing process involved in chronic wound healing.