Nano-hydrogel bandage for non-invasive Raman monitoring of chronic wound healing (Funded by the QUEX Institute)

Chronic wounds (CW), wounds that persist more than 3 months, have been referred to as a major and snowballing public health burden which adversely affects the quality of life. In the US, 25 billion USD is spent annually on treatment of CW and the burden is growing rapidly due to increasing health care costs, an aging population and a sharp rise in the incidence of diabetes and obesity worldwide. CWs comprise of diabetic foot ulcers, pressure ulcers (bedsores), or burns and skin ulcers. Recent advances in sericin hydrogel bandages aid in CW healing, but invariably restricts the assessment of the wound without removing the bandage. Often Reactive oxygen species (ROS) like oxygen, such as superoxide anion, hydroxyl radicals, singlet oxygen, and hydrogen peroxide, have been hypothesized to be increased (~170%) at chronic wound sites and delay healing. However, at lower levels ROS is expected to be beneficial, indeed wound treatments based on ROS modulation have shown promise provided that ROS levels are carefully controlled and appropriately timed. Thus, detecting and monitoring ROS non-invasively (without removing the bandage), would enable ROS modulation therapy to be applied to optimise healing improving patient outcomes and minimising healthcare costs. Thus, the proposed project will explore the development of bandages that can detect ROS from wound site (sweat, pus) directly using a specialized Raman spectroscopy technique enabling us to see through the bandage and quantify ROS species and enable early identification of infections.

These externally wearable nano-hydrogel bandages will be made of polymer or sericin with embedded plasmonic nanostructures carrying the “reporter molecules”. The ROS from the wound site, once absorbed by the hydrogel will be transported to the embedded gold or silver nanostructures where they will chemically interact with the “reporter molecules”. These custom-made reporter molecules will then undergo specific reactions with ROS to give a chemical spectral fingerprint that is detectable using optical vibrational Raman spectroscopy. A suitable specialized hand-held Raman device working on the principles of surface enhanced spatially offset Raman spectroscopy (SESORS) (already built inhouse (Stone, Exeter) will allow sensitive detection from the bandage within a few seconds to
minutes, depending on the need to measure small or large areas. Moreover, the change in chemical signature (due to ROS interaction with reporters) will provide us with the ability to specifically and sensitively determine the concentration of ROS in the wound environment over time (initially to be done with spiked sweat samples) and correlate it to wound healing. This can lead to personalized treatment for the patients and promote healthy living.

This project builds upon work undertaken at Exeter developing SESORS and nanostructures for disease detection and UQ in the development of gold nanostructures modified with Raman reporter molecules for the detection of ROS.