Fig. 5

Colocalization of different-sized SiO₂ particles with lysosomes in J774A.1 macrophages. A Experimental workflow: Cells were exposed to SiO₂ particles of different sizes for 24 h followed by LysoTracker Red staining for 1 h and imaged live. B Representative bright field and confocal images of single cells with the corresponding cytofluorograms show colocalization of 119 nm SiO₂-Cy5 particles (green) with lysosomes (red). C Colocalization of 920 nm SiO₂-Cy5 particles (green) with lysosomes (red). Co-localized pixels appear in yellow. Scale bar: 10 µm. The corresponding histograms of fluorescence intensities of each channel is shown in Additional file 1: Fig. S5A and the bright field images identifying cell morphology in Additional file 1: Figure S6. Quantification of colocalization of D. 119 nm SiO₂-Cy5 particles and E 920 nm SiO₂-Cy5 particles with LysoTracker Red probe was performed using the ImageJ software with JACoP plugin (n = 10 cells). Data is presented as Pearson’s correlation coefficient (PCC) and Manders’ overlap coefficients, where M1 represents the fraction of particles-associated pixels overlapping with lysosomes and M2 the fraction of lysosome-associated pixels overlapping with particles. Statistical analysis was performed using unpaired t-test in GraphPad Prism software: ***p < 0.001, ns: not significant