Fig. 1

Preparation and characterization of the DDAB/PLGA Nano-vaccine (OVA@DDAB/PGA Nv). a Schematic illustration of the OVA@DDAB/PLGA Nv preparation. b SEM images and size distributions of OVA@DDAB/PLGA Nv, bar = 100 nm. c Zeta potential of PLGA NPs, DDAB/PLGA NPs and OVA@DDAB/PGA Nv in pH 7.4 PBS. d Illustration of OVA@DDAB/PLGA Nv uptake by DCs and escape from lysosome. e Antigen intracellular localization from pure antigen (OVA), antigen-loaded Al (OVA@Al), OVA@DDAB/PLGA Nv in BMDCs was observed by CLSM. Antigens were labeled by FITC (green points); lysosomes were labeled by Lyso-Tracker Red (red points); cell nucleus was labeled by DAPI (blue); bar = 20 μm. f Antigen uptake by BMDCs was measured by flow cytometry. g Different groups of vaccine adjuvant-based OVA (5 μg) were cross-presented by BMDCs and B3Z in vitro. h Different concentrations of free OVA (5, 50, 100, 1000, 5000, 12,500 μg) were cross-presented by BMDCs and B3Z in vitro. Cross-presentation of B3Z cells was determined by β-galactosidase activity using a colorimetric LacZ assay (absorbance 570/620 nm). Graphs shown represent results of three independent coculture experiments. Data are expressed as Mean ± STD (n = 3) (*p < 0.05; **p < 0.01; ***p < 0.001)