Fig. 2

Efficient loading and delivery of antigens by the DMSN. (A) The purified RBD of SARS-CoV-2 was analyzed by SDS-PAGE. (B–C) The DMSN could effectively load the RBD and peptides. The DMSN was mixed with FITC-RBD (B) or FITC-peptide (C) at a mass ratio of 5:1 and incubated overnight at 4 °C with rotation. After centrifugation, the encapsulation efficiency of the DMSN was calculated according to the protein or peptide content in the supernatant. The data are presented as the mean ± s.e.m. Two-tailed Student’s t-test test was used for the statistical analysis. ***p < 0.001. (D–E) The DMSN facilitated the uptake of the RBD and peptide antigens by THP-1-derived macrophages. FITC-RBD or FITC-peptide was incubated with THP-1-derived macrophages with or without the DMSN. Fluorescence images (D) and 3D reconstruction images (E) were examined by Leica STELLARIS 5 confocal microscopy. (D) The colocalization of the DMSN and RBD/peptide was quantified along a black arrow