br Fig a The cell viability of L fibroblast
Fig. 6. (a) The cell viability of L929 fibroblast incubated with FeSiAuO with diﬀerent concentrations for 24 h and 48 h. (b) The confocal laser scanning microscopy images (scale bar is 25 μm) of HeLa Imatinib (STI571) at 560 nm laser irradiation (0.2 W/cm2) with diﬀerent time. The cell is incubated with FeSiAuO sample (400 μg/mL) and stained with Dapi and [Ru(dpp)3]Cl2 as the nucleus and dis-solved O2 probes, respectively.
period with the 560 nm light irradiation. From these result, we can further confirm that the FeSiAuO can serve as the nano-carrier with the oxygen generation ability.
After loading the DOX, the uptake process of the FeSiAuO-DOX-PEG was investigated firstly. Fig. 7 shows confocal laser scanning micro-scopy images (CLSM) of FeSiAuO-DOX-PEG and HeLa cells co-cultured for 30 min, 1 and 3 h, where the uptake of DOX in cells was tracked by detecting the luminescence properties of diﬀerent fluorescent sub-stances in cells. Blue fluorescence is the characteristic fluorescence of DNA in cell stained by DAPI under ultraviolet excitation. The middle column green fluorescence emission is from the loaded DOX. In the first 30 min, there is less green fluorescence in the cytoplasm and nuclei, indicating that certain amount of FeSiAu-DOX-PEG nanoparticles were taken up by HeLa cells. When the time prolong to 1 h and 3 h, a stronger green emission appeared in the cells, implying that more nanoparticles were taken up by the cells, whose rapid uptake capacity is mainly owe to the small particle size nanoparticles (20 nm), which proves that FeSiAu-DOX-PEG composite can be used as a release carrier for drug delivery to improve the eﬃcacy of the drug. Colloids and Surfaces B: Biointerfaces 173 (2019) 335–345
3.4. In vitro cancer cell inhibition eﬀect of the FeSiAuO-DOX-PEG
To demonstrate the inhibition eﬀect of FeSiAuO-DOX-PEG to cancer cells, a series of comparative MTT tests including control, and irradia-tion with 560 nm light, FeSiAuO-DOX-PEG, DOX and FeSiAuO-DOX-PEG + 560 nm were conducted, as shown in Fig. 8a. Compared with groups of the blank control and irradiation with 560 nm light, the groups of FeSiAuO-DOX-PEG, DOX and FeSiAuO-DOX-PEG + 560 nm shows higher toxicity to cancer cells with increasing concentration. When the concentration is up to 500 ug/mL, the cell viability of FeS-iAuO-DOX-PEG cultured decreased to less than 23% in the absence of light, which is higher than that of 8% cell viability for DOX group be-cause of the inadequate release of the DOX. Meanwhile, the cell via-bility can be further decreased to 4% for the group of FeSiAuO-DOX-PEG +560 nm light irradiation. Considering the viability of DOX group, this high cell inhibition eﬀect can be further attributed to the dissolved oxygen generation from the FeSiAuO-DOX-PEG under light irradiation. Therefore, it can be inferred that light can promote the production of oxygen, thereby improving the hypoxic microenvironment, making the chemotherapy eﬀect of DOX more obvious.
The cell inhibition and magnetic targeting eﬀect of the FeSiAuO-DOX-PEG can be further confirmed by the fluorescence images of the Hela cells treated with magnetic field and incubated with FeSiAuO-DOX-PEG, AM and PI under the laser scanning confocal microscope. As shown in Fig. 8b, three slides with Hela cells were put into the petri dish with culture medium containing FeSiAuO-DOX-PEG (400 μg/mL). The petri dish was put onto two magnets under the slide (a) and (c) quickly. After gentle shaking for 30 s and cultured in the incubator for 10 min, the cells on slide (a) was irradiated with 560 nm light (0.2 W/cm2) for 20 min (10 min per break for 5 min). Afterward, the cells in the petri dish were tained with AM and PI. From the fluorescence images of the three slide, we can observe that the most of cells on the slide(c) were dead while only several cells on slide (b) were dead, which meaning that more FeSiAuO-DOX-PEG were attracted by the magnet. Besides, the DOX molecule released from the FeSiAuO-DOX can also spread to the slide (b). Simultaneously, compared with (c), all the Hela cells on slide (a) were dead, indicating that the light irradiation can promote the cell inhibition eﬀect, coinciding with our previous results.