Fig. 4

Evaluation of macrophage uptake efficiency of the HIDPPDNEs in vitro. I Representative DOX-derived fluoromicroscopic images of DH82 cells after co-culture with the HIDPPDNEs (A–F) or IDPPDNEs (a–f) at 37 °C for 0 (A/a), 0.5 (B/b), 2 (C/c), 6 (D/d), 12 (E/e), and 24 (F/f) h. The cells in all groups were washed twice with PBS prior to the photographing. All images were photographed at ×400 magnification. Scale bar 15 μm. II Quantitative analyses of the remaining rates of HIDPPDNEs or IDPPDNEs after co-culture with the DH82 cells for different time. Values are mean ± s.d. (n = 3). *P < 0.05