Fig. 4.

The percentage remaining of ATRA loaded in PEG₇₅₀-DPPE micelles (close symbols) and ATRA in 75% methanol/HBS solutions (open symbols) stored in oxygen, nitrogen, and ambient air under light exposure. Black diamonds and white diamonds represent amount of ATRA in oxygen-filled environment, black squares and white squares represent amount of ATRA in nitrogen-filled environment, and gray triangles and white triangles represent amount of ATRA in ambient air. *P ≤ 0.01 compared with ATRA in 75% methanol/HBS solutions