Fig. 2
Cellular uptake and intracellular localization of IONPs-PAA-PEG-MAN in macrophages. Time-dependent and dose-dependent cellular uptake of (A) C6@ IONPs-PAA-PEG and (B) C6@IONPs-PAA-PEG-MAN in THP-1 cells, n = 3. C Time-dependent and dose-dependent cellular uptake of C6@IONPs-PAA-PEG-MAN in HLMVEC cells, n = 3. D Cellular uptake of IONPs-PAA-PEG-MAN and IONPs- PAA-PEG in THP-1 cells after 1 h treatment by analyzing Fe (iron element) concentration, n = 3, t-test analysis was applied for the comparative analysis of data, *p < 0.05. E Cellular uptake of C6@IONPs-PAA-PEG-MAN by THP-1 cells under different endocytosis inhibition conditions, control group is treated without any inhibition conditions for C6@IONPs-PAA-PEG-MAN uptake analysis, n = 3, ANOVA-Tukey analysis was applied for the comparative analysis of data, *p < 0.05, ***p < 0.001. F Intracellular uptake of C6@IONPs-PAA-PEG-MAN by THP-1 cells with free mannose competition, control group is treated without mannose for C6@IONPs-PAA-PEG-MAN uptake analysis, n = 3, ANOVA-Tukey analysis was applied for the comparative analysis of data, *p < 0.05, **p < 0.01. G In vitro drug release of Rif@IONPs-PAA-PEG-MAN under different pH environments, n = 3. H Fluorescence imaging for intracellular localization of C6@IONPs-PAA-PEG-MAN with lysosomes in THP-1 cells, white arrows indicate the co-localization of IONPs-PAA-PEG-MAN with lysosomes, scale bar: 20 μm. I–K Representative TEM images of THP-1 cells after incubation with IONPs-PAA-PEG- MAN, yellow arrows indicate the IONPs-PAA-PEG-MAN in endocytosis vesicles (EV) at the early stage of cell uptake, red arrows indicate the IONPs-PAA- PEG-MAN in lysosomes and white arrows indicate the IONPs-PAA-PEG-MAN in the cytoplasm, scale bar: 500 nm. For TEM imaging, THP-1 cells were seeded at a density of 1 × 106 into 6 plates with 100 nM PMA stimulation for 24 h. Cells were treated with IONPs-PAA-PEG-MAN for 12 h, and then collected, washed with PBS and fixed by 2.5% glutaraldehyde and 2% paraformaldehyde for 48 h at 4 ℃. The fixed cell samples were washed with PBS and then further fixed with 0.1% osmic acid for 2 h. After washed with PBS, the samples were dehydrated with sequential treatment of 50%, 70%, 85%, 90%, and 100% ethanol, respectively. Then, the samples were embedded in resin, cut into ultrathin slices, stained with 2% uranyl acetate and 0.2% lead citrate before TEM observation