Low Temperature Air Plasmas for Wound Healing Applications

Chronic wounds present a huge socio-economic burden across the world. With current treatment strategies remaining inefficient and unreliable, new therapeutics are desperately sought. One potential new therapeutic for chronic wounds is the use of Low Temperature Plasmas (LTPs) which are showing promise in laboratory and clinical trials for chronic wound healing. LTPs are electrically produced, gaseous, chemically reactive environments consisting of electrons, electric fields, photons and Reactive Oxygen and Nitrogen Species (RONS). These are able to synergistically activate biological pathways by mimicking the function of RONS produced physiologically to mediate many processes, including wound healing. For development of LTP-based treatments, the types and concentrations of RONS delivered to a target site, and their effects on target cells need to be understood. In this work, global modelling is used to understand the time-evolved species densities in atmospheric pressure nitrogen and nitrogen/oxygen discharges, and also to determine the dominant production and destruction reactions for biorelevant species. Development of a new detailed nitrogen chemistry set has identified the importance of vibrationally excited nitrogen in atmospheric pressure discharges. Extension of the nitrogen set to include oxygen species has allowed the process of benchmarking air simulations to experimental data, and shows the dominant production and destruction pathways of the biorelevant species, nitric oxide and ozone. For use in future work, a protocol for correlation of the plasma RONS composition delivered in a particular treatment to skin cells, and the biological effects seen has also been developed. This has been achieved by combining realtime cellular viability assays, and the global modelling methods. This work is a first step to relating LTP RONS composition to biological effects, and will help inform the future design of LTPs for all purposes, including those for chronic wound therapies.