## 2 Results and Discussion
### Characterization and In Vitro Diffusion Study of PEs
#### 2.1.4 In Vitro Diffusion Studies through Artificial Membranes  
Our goal was to formulate an emulsion that is capable of delivering the antifungal drugs through the nail plate and retain the drugs in the site of the infection (nail bed) for a prolonged time to provide a sustained drug release. The diffusion studies of PEs on the artificial membranes were performed in Franz diffusion vertical cells in order to examine the drug delivery ability of the formulated PEs. For diffusion studies, we applied PEs, CE, and ES of the same concentration, 17.91 mg/mL, as an antifungal drug combination. Because of the droplet size similarity between the CE and PEs, we can assume that only the dosage form determined the diffusion properties of the drug. We found that PEs possessed better drug delivery properties through agar gel membrane compared to CE and ES (Table 4 and Figure 2). We examined the diffusion properties of PEs with different droplet sizes and found that the PEs with smaller droplet size (1.85 \(\upmu\)m) could deliver as much as 89.9% of TIO through the agar membrane. In the experiment where the composite membrane was used, we found that the ES had diffused through the composite membrane structure, and only a small portion (2.4%) of the drug remained in the composite membrane (Table 4 and Figure 3). The PE 20 ET delivered 89.9% of TIO through the agar gel membrane, and only 5.7% had diffused through composite membranes, suggesting that 84.2% of the applied drug remained in the targeted area. This amount was 61.1% at PE 50 ET and 45.13% at PE 100 ET. These in vitro experimental results suggested that PEs had better on-site drug delivery properties. \begin{table}
\begin{tabular}{c c c c c c} \hline  & \multicolumn{2}{c}{**PE 20 ET**} & \multicolumn{2}{c}{**PE 50 ET**} & \multicolumn{2}{c}{**PE 100 ET**} \\ \hline
**Coil Phase** **(mg/mL)** & **Droplet Size (nm)** & **Stability** & **Droplet Size (nm)** & **Stability** \\ \hline
0.90 & 4306 \(\pm\) 39.6 & 10 min & 1280 \(\pm\) 62.8 & 1 day & 1070 \(\pm\) 438.5 & 30 min \\
1.79 & 615 \(\pm\) 22.2 & 30 min & 1320 \(\pm\) 95.9 & 1 day & 1350 \(\pm\) 531.8 & 30 min \\
2.69 & 890 \(\pm\) 103.3 & 30 min & 1440 \(\pm\) 83.5 & 1 day & 1630 \(\pm\) 464.5 & 30 min \\
3.58 & 1250 \(\pm\) 94.5 & 1 day & 1650 \(\pm\) 51.5 & 2 day & 1730 \(\pm\) 514.5 & 10 min \\
4.48 & 1320 \(\pm\) 32.5 & 8 weeks & 1670 \(\pm\) 216.8 & 2 day & 1850 \(\pm\) 107.9 & 10 min \\
5.37 & 1440 \(\pm\) 100.2 & 8 weeks & 1620 \(\pm\) 79.7 & 8 weeks & 1890 \(\pm\) 333.8 & 10 min \\
6.27 & 1470 \(\pm\) 35.2 & 8 weeks & 1610 \(\pm\) 34.4 & 8 weeks & 1950 \(\pm\) 95.0 & 10 min \\
7.16 & 1470 \(\pm\) 62.5 & 8 weeks & 1670 \(\pm\) 62.8 & 8 weeks & 1940 \(\pm\) 20.1 & 1 week * \\
8.96 & 1660 \(\pm\) 56.7 & 8 weeks & 1690 \(\pm\) 70.4 & 8 weeks & 2070 \(\pm\) 51.2 & 1 week * \\
11.19 & 1890 \(\pm\) 41.2 & 20 weeks & 2200 \(\pm\) 188.9 & 8 weeks & 2200 \(\pm\) 59.5 & 1 week * \\
13.43 & 1840 \(\pm\) 141.0 & 20 weeks & 2250 \(\pm\) 170.8 & 2 weeks * & 2800.0 \(\pm\) 85.7 & 1 week \\
16.12 & 1820.0 \(\pm\) 99.6 & 20 weeks & 2080 \(\pm\) 160.1 & 2 weeks * & 2850 \(\pm\) 184.3 & 1 week \\
17.91 & 1850 \(\pm\) 496.6 & 8 weeks & 2380 \(\pm\) 157.0 & 2 weeks * & 3090 \(\pm\) 116.6 & 1 week \\ \hline
**Coil Phase** **(mg/mL)** & **Appearance** & **Appearance** & **Appearance** **PET 20 ET** & **0.90** & **0.90** \\
0.90 & creaming & sedimentation & creaming & 1.79 & 1.79 & 1. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Samples** & **Stabilizing Agent** & **Droplet Size (nm)** & **CA Agar Gel (\%)** & **CA Composite Agent Gel (mg/cm2)** & **CA Composite Membrane (\%)** & **CA Composite Membrane (mg/cm2)** \\ \hline ES & - & - & 18.33 & 0.26 & 15.90 & 0.22 \\ CE & Tween80 & \(2470.0\pm 89.1\) & 35.02 & 0.49 & 11.01 & 0.15 \\ PE 20 ET & 20 ET SNPs & \(1850\pm 496.6\) & 89.88 & 1.26 & 5.70 & 0.08 \\ PE 50 ET & 50 ET SNPs & \(2380\pm 157.0\) & 67.18 & 0.95 & 6.06 & 0.05 \\ PE 100 ET & 100 ET SNPs & \(3090\pm 116.6\) & 45.22 & 0.63 & 0.09 & 0.001 \\ \hline \hline \end{tabular}
\end{table}