Fig. 7.

Particulate alum via Pickering emulsion (PAPE) as an enhanced COVID-19 vaccine adjuvant. (A) A schematic of the PAPE synthesis process. (B) Uptake of PAPE for enhanced antigen-presentation to DCs in vitro. Confocal images showing the intracellular distribution of RBD (red) with lysosomes (green) of PAPE and alum. (C-D) Humoral responses to PAPE vaccination in BALB/c mice. 6–8-weeks-old BALB/c mice were vaccinated with 100 µl suspension of various formulations along with 5 µg of RBD on day 0 and day 14 through intramuscular injections (n = 6). Serum samples were collected 28 days after the initial immunization for IgG titer analysis, and splenocytes were collected 30 days after the initial immunization for cytokine analysis. (C) Serum RBD-specific IgG and IgG2a titers. (D) ELISpot analysis of IFN-γ spot-forming cells among splenocytes. Reproduced with permission from ref [83]. Copyright 2020 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.