Pd@insulin clusters reverse excessive ROS accumulation, rescue neuronal loss, inhibit microglial activation, and reduce apoptosis after TBI. A Brain ROS level by flow cytometry analyses for Negative, Sham, TBI and TBI mice treated by Pd@insulin mice (10,000 cells per group), and B quantitative analysis (n = 6). C Representative immunofluorescent staining images of NeuN, doublecortin, Sox2, cleaved caspase 3, IBA1, GFAP, TNFα, IL6, BDNF, and TUNEL in injured cortex of TBI mice (Scale bar 100 μm), and D corresponded quantitative analyses (n = 3). Data are all shown as mean ± SD. Statistical analysis of (B, D) was performed by one-way ANOVA with a Tukey post hoc test.