Quantifying the concentration and penetration depth of long-lived RONS in plasma-activated water by UV absorption spectroscopy

Abstract

Reactive oxygen and reactive nitrogen species (RONS) are believed to play a key role in biomedical applications, which means that RONS must reach the target tissue to produce a therapeutic effect. Existing methods (electron spin spectrometry and microplate reading) to determine the RONS concentration are not suitable for experimental real-time measurements because they require adding an indicating reagent to the plasma-treated medium, which may alter the chemical composition of the medium. In this paper, we propose a method to measure the long-lived RONS concentration in plasma-activated water (PAW) by using UV absorption spectroscopy. Based on an analysis and fit of the absorption spectra of standard solutions (H2O2, NaNO2, and NaNO3), we propose a detailed fitting procedure that allows us to calculate the concentrations of simplex H2O2, NO2−, and NO3−. The results show that the pH and the cross reactivity between RONS in PAW correlate strongly with the absorption spectra. To confirm the accuracy of the calculations, we also use a microplate reader and add chemical reagents to measure the concentrations of H2O2, NO2−, and NO3−. The results show that the concentrations calculated by the proposed fitting method are relatively accurate and that the error range is acceptable. Additionally, the time-dependent diffusion of RONS in PAW is measured and analyzed at different depths in the PAW. This fitting approach constitutes a nonintrusive approach to measure RONS at different depths in PAW.

Spectral Characteristics of Needle Array-Plate Dielectric Barrier Discharge Plasma and Its Activated Water

“…At the needle-dielectric plate distance of 4 and 5 cm, the voltages are 15 (Figure 10(a)) and 20 (Figure 10(e)) kV, respectively. e UV/Vis spectra of these two images, that is, same contours and peak positions, are similar to those obtained by Oh et al [25] and Liu et al [27]. At the needle-dielectric plate distance of 4 and 3 cm, a voltage of 20 kV (Figures 10(b) and 10(d)), and treatment of 10 min, the UV/Vis spectra are the same as those observed in previous studies.…”

“…( erefore, H 2 O 2 absorption was separated from total absorption. e concentration of H 2 O 2 in the solution could be calculated using the absorbance of PAW at 250 and 255 nm [27].…”

“…e concentration of NO − 2 could be calculated using the absorption peak at 540 nm. 2 by using the following equations [27]:…”

“…e concentrations of H 2 O 2 and NO − 3 increase with increasing voltage, proximity of the needle-dielectric plate distance, and treatment time. In the study of Liu et al, the maximum concentrations of H 2 O 2 and NO − 3 can reach 2.2 and 9 mg/L, respectively[27]. In the study of Oh et al, the concentration of H 2 O 2 is always below 1 mg/ L, and the highest concentration of NO − 3 is around 0.5 mg/L[31].…”

Adjusted multiple gases in the plasma flow induce differential antitumor potentials of plasma‐activated solutions

“…[ 24–27 ] Plasma‐treated water (PTW) derived from various plasma sources under the different conditions has been well evaluated with respect to generated chemical species, stabilities, and reactivities. [ 28–31 ] Shainsky et al [ 32 ] reported that acidified plasma‐treated water produced by air or oxygen in a closed plasma system exhibited different pH stability and oxidizing properties. Other investigations have reported that two different types of plasma devices fed with air were compared, and it was revealed that the differential reactivities against antimicrobial and organic decomposition were induced due to the differential reactive species composition and its stability, even after post‐treatment storage.…”