Fig. 2.

Preparation and characterization of virus-mimetic nanoparticles. (a) Schematic of the preparation of VNPs by conjugating antigenic proteins and agonists with polydopamine nanoparticles via in situ polymerization. Gray and blue means PDA-NPs and the attached adjuvant and antigen, respectively. (b, c) TEM images of PDA-NPs (b) and VNPs (c). Scale bar, 200 nm. (d, e) Size distribution (d) and zeta potential (e) of PDA-NPs and VNPs measured by DLS. (f, g) Flow cytometry histograms (f) and mean fluorescence intensity (MFI) (g) of PDA-NPs without S1 and VNPs with FITC-labeled S1. Data are mean ± SEM (n = 3). Statistical analysis was performed using Student’s t-test; ^***P < 0.001. (h, i) Loading efficiency (h) and loading capacity (i) of R848 in VNPs at different feed concentrations measured by UV/vis spectrophotometry. Data are mean ± SEM (n = 3).