Fig. 1

DEX-PS uptake behavior by different macrophage subtypes. Mean fluorescence of whole cells (a) and Nile Red⁺ cells (b), and percentages of Nile Red⁺ cells (c) after incubation with various NPs. Representative confocal laser-scanning microscopy images of M1 (d) and M2 macrophages (e) incubated with PS, COOH-PS, or DEX-PS for 4 h. Kinetic profile of mean fluorescence of whole M1 (f) and M2 macrophages (g). Rate of DEX-PS uptake by M1 (h) and M2 macrophages (i) influenced by various inhibitors. j Fluorescence distribution of DEX-PS in MMR⁺ and MMR⁻ cells. Scale bars in d and e indicate 20 µm. Data are presented as the mean ± SD (n = 3), * Indicates p < 0.05. COOH-PS: carboxyl-functionalized polystyrene; DEX-PS: dextran-functionalized polystyrene; MMR: macrophage mannose receptor; PS: polystyrene