Fig. 4
OPLS-DA scores plots (left panel) and corresponding volcano plots (right panels) derived from the 1H NMR data of kidney, liver, lung, and spleen obtained from the pairwise groups at 48 h post-administration of mid-size Fe@Si-NPs. C and M represent the control group and the mid-size Fe@Si NPs group (around 20 nm in diameter), respectively, 48 represents 48 h post-treatment. Marked dots in color volcano plots represent metabolites with statistically significant differences. Keys for the assignments are shown in Additional file 1: Table S1