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The University of Southampton
Medical Devices and Vulnerable Skin Network

Queen Mary University of London


Design and in vitro testing of soft, biodegradable electrochemical sensors for O2 and glucose monitoring at wound sites

Oxygen and glucose measurement at a chronic wound surfaces offers a route to tracking the progression of healing. As metabolic surrogates they can reflect a balance of regenerative, inflammatory and local vascularisation processes, particularly given the high metabolic activity of inflammatory cells. Techniques for direct, local measurement are limited to O2 and not appropriate for beside use. However, there is evidence that hypoxia compromises skin repair.

This project will investigate degradable protein based electrochemical sensors formulated from multiple specialist protein layers for tracking of wound pO2 and glucose. Such devices would be conformal, non-intrusive and avoid the need for device retrieval. Measurement would be by direct electrochemical detection of oxygen using at a cathodic polarised electrode surface and of glucose at an anodic surface via an immobilised glucose oxidase layer generating H2O2 .

These robust, established chemistries rely on noble metal/artificial polymer components. We will use cross linked protein films, with one layer coated with a biocompatible organic conducting polymer for the electrochemical reactions: poly(3,4 ethylenedioxythiophene):poly(styrenesulphonate) (PEDOT):PSS.

The special feature will be our use of dense protein membrane barriers formed with a highly reactive acyl chloride cross linker to shift film density, and therefore permeability control to the micro solute scale. This will reduce target molecule consumption for ultra-small volume use, i.e. the wound surface. Film density and composition, variously using BSA, collagen, fironectin, and elastin like proteins for charge density and mechanical integrity variation will be designed for controlled permeability, critically correlated with selectivity, stability and degradation. The latter will be evaluated in proteolytic enzyme loaded model biofluids. Device surface and bulk structure integrity will then be correlated with sensing performance as a predictor of operational lifetime. Connectivity will be through adhesive conducting films (Au, Cu) insulated using degradable polymer.

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