Wb 2000

The DOM and the obtained fractions (i.e., F1 and F2) were characterized according to their pH, DOC, and specific UV absorbance. The specific UV absorbance (SUVA) was defined as the ratio between UV absorbance and DOC for a 10 mgC L -1 sample at pH 6.5 (10 -3 phosphate buffer) measured at a wavelength of 254 nm (UV/Vis spectrophotometer; Unicam) (Edzwald and Tobiason, 1999) . For spectroscopic analyses of IR-FT and 1 H-NMR, the DOM and fraction samples were concentrated in a rotavapor (WB 2000; Heidolph) . These samples were then dried in a vacuum oven (VTR 5036; Heraeus) at 40 °C for 24 h.

Preparation of nPEVs using the thin film hydration method Sertaconazole nPEVs were prepared using the thin-film hydration technique followed by sonication (Nasr et al., 2008a; Bsieso et al., 2015) . Three nail penetration enhancers were chosen for the current study; N-acetyl-L-cysteine, thioglycolic acid and thiourea. The composition of the differently prepared nPEVs is shown in Table 1. In all prepared nPEVs, 100 mg of sertaconazole, 400 mg of phosphatidylcholine, 200 mg of transutol and 20 mg stearylamine in addition to a certain amount of nail penetration enhancer (as described in Table 1) were accurately weighed and dissolved in chloroform: methanol mixture (2:1, v/v). The organic solvent mixture was evaporated (Rotary evaporator, Heidolph WB 2000, Germany) under reduced pressure at 40 C and 150 rpm, so that a thin film of dry lipid with the drug was formed on the inner wall of the flask. The dry lipid film was hydrated with 5 ml of phosphate buffer (pH 7.4) with or without ethanol, as shown in Table 1 through portion-wise addition. The dispersion was mechanically rotated for 30 minutes at 40 C, followed by sonication (Julabo USR 3, Germany) for 15 minutes to reduce the size of the vesicles, and storage at 4 C.