Fig. 4

a Effects of drug concentration and incubation time on drug loading of macrophages. Data are expressed as mean ± SD (n = 3). b Cytotoxicity of DOX and DOX/PEG-BPEI-rGO towards RAW264.7 cells for 12 h. Data are expressed as mean ± SD (n = 3). **p < 0.01, ***p < 0.001. c Flow cytometry profiles of DOX fluorescence from DOX/PEG-BPEI-rGO and free DOX in RAW264.7 cells under different NIR irradiation conditions