3.4 Cellular localization of UCNP-based nanocarrier in tumor cells
The efficiency of PDT treatment is highly dependent on PS cellular uptake and accumulation in malignant tissues (Nawalany et al., 2009). The fate of the UCNP-based carrier in tumor cells were investigated using confocal laser scanning microscopy. As shown in Figure 7, the confocal microscopy assay was based on the red autofluorescence of Pha, and the blue fluorescence from DAPI bound to the nucleus, and F-actin in the cytoplasm stained by Alexa Fluor 488 phalloidin.
For MCF7 cells treated with free Pha, the red fluorescence signal from Pha detected in MCF7 cells was quite weak (Figure 7B). On the other hand, UCNP-based Pha carriers, FA-PEAH-UCNPs-Pha and CH3-PEAH-UCNPs-Pha, showed higher red fluorescence Pha signal compared with the free Pha sample. Especially, after FA-PEAH-UCNPs-Pha treatment, MCF7 cells produced strong red fluorescence from Pha around the nucleus and at the inner part of the cells, indicating that Pha molecules were effectively internalized into the MCF7 cells (Figure 7D). The results indicate that the UCNP-based Pha carrier improved the Pha water solubility, and FA ligands could effectively enhance the cellular uptake of Pha molecules into MCF7 cells by an active targeting effect. These strong fluorescence signals from Pha could be also used to clearly understand the dynamics of signal transduction in the intracellular networks and in diagnostics.