Exploring chemical modifications caused by the COST-Jet in NO-rich gas admixtures by means of FTIR and Mass Spectrometry on the simple biological model cysteine

Cold atmospheric plasmas (CAP) can be used as an effective treatment for chronic wounds, cancer, and even antibiotic-resistant bacterial infections1. Among the myriad reactive species that are produced in CAPs, nitric oxide (NO) is theorized to play a crucial role in these applications. Research has shown that NO restricted bioavailability is one of the main causes of complications in wound healing, infections, and decreased tissue microcirculation2. Since chemical modifications can have complex reaction pathways, the amino acid cysteine was used to represent a simple biological model, as previously introduced, due to its amino, carboxyl, and thiol groups that are prevalent in well studied biological macromolecules3. In this research, we use the Capacitively Coupled Atmospheric Pressure Microplasma Jet (COST-jet)4, with a synthetic air admixture (1 slm He, 2 sccm O2, and 8 sccm N2) that has been shown to produce the highest NO densities in the effluent5, in order to understand the chemical modifications that this NO-rich plasma produces in a simple biological model: cysteine. These modifications were analyzed through mass spectrometry and Fourier Transform Infrared (FTIR) spectroscopy for different treatment times in order to understand their possible biological relevance.