Fig. 5: Transdermal delivery of SARS-CoV-2 vaccine.

a A schematic illustration for transdermal delivery of the SARS-CoV-2 vaccine and the triggered immune responses. After transdermal delivery, such SARS-CoV-2 nano-vaccines could activate immune cells such as DCs in the dermis, or migrate to the nearby lymph nodes for immune activation. b Schematic illustration of the experimental design showing transdermal delivery of SARS-CoV-2 vaccine. c, d DLS (c) and zeta potential (d) of FCS-based transdermal vaccines with different mass ratios from 1:1:1 to 3:1:1 (n = 3). e, f The skin penetration ability of FCS-based transdermal vaccine with different mass ratios (n = 3). Total dosage: 200 μg/cm² (g) SARS-CoV-2 specific IgG antibody titers at different time intervals determined by ELISA (n = 4). h Quantification of CD4⁺ T cells, CD8⁺ T cells in the spleen at day 28 (n = 6). i Quantification of IFN-γ⁺ secreting CD4⁺ T cells (CD3⁺CD4⁺ IFN-γ⁺) and j CD8⁺ T cells (CD3⁺CD8⁺ IFN-γ⁺) in the spleen at day 28 (n = 6). k, l Quantification of OVA-Cy5.5⁺ (CD45⁺CD11c⁺Cy5.5⁺) in DCs in k lymph nodes and l skin (n = 4). m, n Quantification of m DC maturation (CD45⁺CD11c⁺CD86⁺) and n T cell receptor (TCR) activation (CD45⁺CD3⁺CD8⁺CD69⁺) in lymph nodes (n = 4). All illustrations were created with BioRender.com. The representative flow cytometric plots were illustrated in Figs. S22 & S23. Data are presented as mean ± standard deviation. Statistical significance was calculated via one-way ANOVA with a Tukey post-hoc test. *P < 0.05; **P < 0.01; ***P < 0.001. Source data are provided as a Source Data file.