Fig. 3

The in vivo tumor targeting and internalization by various cells at tumor sites of the 4T1 breast cancer model. a Specific accumulation of free DiR, D-Lipo, D-bLP, and DM-bLP at tumor sites (red arrows) by in vivo imaging system. b The ex vivo imaging of each group in major organs. c Quantified distribution of each group in major organs (n = 3). The data are means ± SD, *p < 0.05 (two-tailed Student’s t test). d Intratumoral distribution of various nanosystems measured by photoacoustic imaging (green signals in the captured images). e Internalization of various nanosystems by CAF at tumor sites. CAF was denoted as cells of α-SMA-positive (green signals) without co-localizing with CD31 (white signals) to avoid the interference of EC. Yellow arrows, CAF; white arrows, EC. f Internalization of various nanosystems by TAM at tumor sites. Green signals, TAM; yellow arrows, co-localization of nanosystems with TAM. g Internalization of various nanosystems by 4T1-GFP cancer cells at tumor sites. Green signals, 4T1-GFP cancer cells, yellow circle arc, 4T1-GFP cancer cells regions, scale bar, 25 µm