4.7. Photostability Test

To assess the photostability of the patch, a selected film from factorial design optimization was placed in the cuvette holder using the cuvette setup described in Figure 4C. The cuvette was exposed to a 150 W halogen lamp placed 1 cm away and for 5 h. The lamp was a Fiber-lite MI-150 high intensity illuminator from Dolan Jenner Industries (color temperature 3250 K). The experiment was conducted in a cold room at 8 °C to rule out temperature effects. The patch was immersed in potassium phosphate buffer, 10 mM, and pH 7 and left at least 15 min to temperature equilibrate. Dye alone was run as a control. Absorbance and fluorescence spectra were recorded at every 30 min during the whole irradiation period.