Fourier-transform infrared spectroscopy analysis of human stratum corneum treated with different formulations as a function of pH. Representative spectra highlighting wavenumbers characteristic of C-H stretching in stratum corneum lipids after pre-treatment with (A) PBS, (B) NLS, and (C) magainin + NLS for 15 H and soaked in PBS at pH 5, 7.4, and 10 (shown from top to bottom). Dashed lines identify peaks of interest. Change of (D) CH2 asymmetric stretching frequency and (E) CH2 symmetric stretching frequency for stratum corneum pre-treated with PBS (●), NLS (■), and magainin + NLS (△) determined from graphs like (A), (B) and (C), respectively. Data represent averages of n ≥ 3 samples ± standard error of the mean. The * symbol identifies wavenumbers significantly different from the corresponding wavenumber at pH 7.4 (Student’s t-test, p<0.05).