Fig. 3

Cell viability, ROS scavenging properties, and immune-cell modulating responses. (A) Cell viability of pEVs (2 mg mL^− 1), and pEVs loaded GelAlg and GelAlg@rGO determined using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay based on the conversion of MTT into formazan crystals by living cells after 24 h and (B) live/dead assays of PBS, pEVs and pEVs-loaded hydrogels with 5 min of NIR irradiation. (C) Intracellular ROS fluorescence intensities of L929 and (D) Intracellular ROS fluorescence intensities on RAW264.7 cells when in contact with LPS and LPS + pEVs using DCFH. (E) The ratio of the fluorescence signal of CD206 (M2 macrophage biomarker) over CD86 (M1 macrophage biomarker). Data are represented as mean +/- SD, with n = 3 replicates; (ns > 0.05. *p < 0.05). (F) The cells were treated with 100 ng/mL lipopolysaccharide (LPS) for 1 day before being cultivated with various samples for 3 days. Fluorescence microscopic detection of the macrophage polarization