Figure 4.

In vitro cellular uptake and PDT of HeLa cells treated with free TPPS₄ (T), free iodixanol and TPPS₄ (IT), TPPS₄ in NL (LT), and NL co-encapsulating iodixanol and TPPS₄ (LIT). (A) Cellular internalization of TPPS₄ after 18 h incubation with T, IT, LT, or LIT. Images merging the transmission and fluorescence confocal channels are shown. Fluorescence of TPPS₄ (red pseudocolor) was excited by a 543 nm laser. (B) HeLa cells survival one day post-PDT. The dark bars indicate 552 nm laser irradiation and the light ones indicate 640 nm laser irradiation at the same irradiation dose (15 J cm^-2). (**p< 0.01 compared with T, IT and LT at the same laser irradiation dose).