In another experiment, Nile Red was used as a fluorescent probe, because fluorescence is a

more sensitive technique than UV-vis absorption. This classical dye is fluorescent and soluble in

aqueous medium only at acidic pH values. Several fluorescence experiments have been carried

out in order to check the uptake and the environment of the dye after nanocapsule absorption.

Fluorescence spectra of Nile Red were measured in acidic water solution, in nanocapsule

solutions, in a Tween-80 aqueous solution, in ethyl butyrate solution, and on silica gel under

various conditions as shown in Figure 6-7.



 a-






 EI 0
 55 65075
 Wavlegt (nm)

 Fiue67 ieRdeisinsetai ty utrt ouin() nnaoasl ouin()










acidi frm of7 Nile red. eisOn theothrhand in ethel ptrae sence of) Twen-0oth nanocapsulesslto b,a

 fluorescnc signal tyicl of, n Nile Reid in wan sorgaicenironen isotandwihrveh







complete uptake of the dye by both the Tween-80 micelles and the nanocapsules. It should be