Enhanced MHC-I antigen presentation from the delivery of ovalbumin by light-facilitated biodegradable poly(ester amide)s nanoparticles.

The generation of CD8 T cells is crucial in adaptive immunity against cancer and many infectious diseases. Vaccines aimed to stimulate CD8 T cell response typically become ineffective because the antigens are subject to sequestration in endocytic compartments, instead of being delivered cytosolically for MHC-I processing and presentation. In this study, a nano-carrier (Arg-Phe-PEA(AP) nanoparticles) for ovalbumin (OVA) was developed from arginine- and phenylalanine-based poly(ester amide)s, which further formed an electrostatic complex with AlPcS2a, a typical photosensitizer for photochemical internalization (PCI) strategies. The nanocarrier significantly enhanced the internalization efficiency by dendritic cells of both OVA and AlPcS2a. The photochemical interruption of endocytic compartments by the AlPcS2a photosensitizer complexed in the nanocarrier enabled the light-facilitated endosomal escape of OVA. MHC-I presentation and CD8 T cell response were elicited by OVA-loaded Arg-Phe-PEA(AP) nanoparticles when light irradiation was applied at 660 nm. The light-facilitated delivery of OVA was dependent on the light dose and the concentration of the photosensitizer, both in vitro and in vivo. The optimized stimulation of MHC-I response demonstrated the potency of this light-facilitated nano-platform for CD8 T cell-inducing vaccination.