## 3 Results
### Permeation of NTAPP-Generated RONS through Agarose Gel  
In order to investigate the effects of NTAPP applied onto the skin model, 1% agarose gel was used. The experiments were conducted according to the thickness of agarose membrane, as shown in Figure 4a. The distance between the plasma jet and the agarose membrane was kept as 15 mm, where the temperature was below 38 \({}^{\circ}\)C. Agarose models with thicknesses of 1, 2, and 3 mm were used. NTAPP was treated for 10 min, and the UVAS was performed at every 1 min until 30 min post-plasma treatment. Then, the agarose gel was removed, and the cuvette was quickly placed in the UV spectrometer. In the absence of agarose (d = 0 mm), the absorbance value during the plasma treatment, for 10 min, increased linearly. The calculated concentration of each RONS also increased linearly during that time. The tendency suddenly changed when plasma was off. After 10 min of plasma treatment, the concentrations of H\({}_{2}\)O\({}_{2}\), NO\({}_{2}\)\({}^{-}\), and NO\({}_{3}\)\({}^{-}\) were 149.8 \(\upmu\)M, 261.0 \(\upmu\)M, and 129.6 \(\upmu\)M, respectively. After 40 min, the concentrations of H\({}_{2}\)O\({}_{2}\), NO\({}_{2}\)\({}^{-}\), and NO\({}_{3}\)\({}^{-}\) became 116.6 \(\upmu\)M, 245.3 \(\upmu\)M, and 144.7 \(\upmu\)M, respectively. H\({}_{2}\)O\({}_{2}\) and NO\({}_{2}\)\({}^{-}\) decreased and NO\({}_{3}\)\({}^{-}\) increased during the post plasma incubation time. When plasma was treated on the agarose gel membrane located on top of DI water, the absorbance reduced remarkably as shown in Figure 4b. When the membrane thickness was 1 mm, the final absorbance value was 0.6, which is 1/5 of that without the membrane. In contrast to direct plasma treatment, the absorbance continuously increased up to 30 min of the post-plasma treatment time.  
The increase rate became higher when the plasma was turned off and became gentle again about 10 min later. The thicker the agarose gel, the gentler the slope. NO\({}_{2}\)\({}^{-}\), which was measured in the largest amount in direct plasma treatment, was hardly measured with agarose gel. The amount of NO\({}_{2}\)\({}^{-}\) reduced from 245.3 \(\upmu\)M to 4.8 \(\upmu\)M with 1 mm-thickness-agarose gel after 40 min from the starting of plasma treatment. NO\({}_{3}\)\({}^{-}\) became the main permeating component, and the concentration of NO\({}_{3}\)\({}^{-}\) reduced from 144.7 \(\upmu\)M to 50 \(\upmu\)M,  
Figure 3: RONS concentrations in NTAPP treated water according to NTAPP treatment time and distance (**a,d**) H\({}_{2}\)O\({}_{2}\), (**b,e**) NO\({}_{2}\)\({}^{-}\), and (**c,f**) NO\({}_{3}\)\({}^{-}\). All measurements were repeated three times.  
47.2 \(\upmu\)M, and 34.7 \(\upmu\)M with 1 mm, 2 mm, 3 mm thickness-agarose gel after 40 min. Since it is certain that NO2\({}^{-}\) is generated from our NTAPP, it is assumed that NO2\({}^{-}\) cannot permeate the agarose gel or is converted into NO3\({}^{-}\) quickly. H2O2 was measured in an amount less than the measurement limit during plasma treatment, and gradually measured as time passed after the plasma was off. When the agarose film was 2 mm or 3 mm, H2O2 and NO2\({}^{-}\) were hardly detectable.