pH changes in aqueous solutions containing amino acids induced by low-temperature plasma exposure

Low-Temperature Plasma (LTP) has gained attention for its applications in medicine, particularly in cancer therapy. By generating reactive oxygen and nitrogen species in aqueous solutions, LTP induces chemical changes, including changes in pH that may play a crucial role in biological processes. However, its molecular-level effects in such processes remain largely unexplored. Moreover, pH plays a critical role in cancer treatment, influencing invasive growth and drug resistance. Therefore, studying how LTP modifies the pH of biological systems is essential.



In this study, we investigated how LTP exposure influences pH in aqueous solutions, by exploring key plasma parameters: voltage (8 kV and 10 kV), frequency (1 to 4 kHz), and irradiation time (up to 120 s). Additionally, we examined the effect of the solution composition by introducing glycine and serine, amino acids known to impact cancer proliferation. Our results show that LTP leads to acidification in deionized water, with the extent of acidification increasing proportionally with LTP parameters. In the amino acids solutions, glycine presented concentration-dependent pH changes while serine maintained a constant pH across all tested concentrations. Furthermore, FTIR analysis revealed a decrease in absorbance signals after LTP treatment, suggesting amino acid degradation.