Cellular uptake of nanoparticulate LM Fe(III) poly oxo-hydroxide by Caco-2 cells.

<p>A, B, C, D TEM images showing differentiated Caco-2 cells incubated with LM Fe(III) poly oxo-hydroxide. <b>A</b>, arrows show particle clusters adhering to the cell membrane microvilli (scale bar, 500 nm). <b>B</b>, arrows indicate invagination on the cell membrane (scale bar, 100 nm). <b>C</b> and <b>D</b>, arrows indicate Fe accumulation inside the cell (scale bars: panel C, 500 nm and panel D, 100 nm). <b>E</b>, Effect of chemical inhibitors of endocytosis-related pathways on Fe utilization by differentiated Caco-2 cells. Data are shown as a percentage of the controls (without inhibitor) after a 1 h exposure to LM Fe(III) poly oxo-hydroxide (black bars) or Fe(III) maltol (open bars) co-incubated with either chlorpromazine (CPZ), potassium-free BSS (K⁺ depletion), filipin or methyl-β-cyclodextrin (M-β-c), plus 23 h in fresh non-supplemented MEM. Results are mean ± s.d. of 3 independent experiments with 3 replicate wells per experiment for chlorpromazine (*, <i>p</i>=0.02 relative to control) or triplicate wells of the same experiment for the remaining inhibitors. <b>F</b>, Change in TEER in the Caco-2 cell monolayer following a 1 h exposure to chlorpromazine (closed diamonds), K⁺-free BSS (open triangles), M-β-c (open squares) or non-supplemented BSS (closed inverted triangles) and with 23 h further incubation in fresh MEM (24 h total). Values are a percentage of the initial measurement (0 h) and are shown as mean ± s.d. as above. Experimental points are connected with a solid line to aid visualization and not because a linear relationship is assumed between time and TEER measurement. Detailed methodology is available in the Methods Section and in Methods S1.