Membrane sialylation orchestrates cellular gateways: A spatiotemporal analysis of cellular transport using DNA nanocages via membrane charge modulation

Negatively charged DNA nanostructures, such as tetrahedral nanocages, are internalized by cells despite the electrostatic repulsion from the anionic cell membrane, and, paradoxically, cancer cells, which carry intrinsically higher negative charge due to overexpression of sialic acids on their cell surface, show markedly higher uptake than normal cells. This contradiction exposes a fundamental gap in our understanding of how these anionic nanostructures overcome this repulsion. Using chemical modulation of cell-surface sialylation in RPE1 cells to create three groups with altered sialylation levels, together with inhibitor-based dissection of endocytic pathways, we demonstrate that an increase in cell surface sialylation governs the uptake of DNA tetrahedra not through electrostatics but by structurally remodeling the cell membrane via rearrangement of the GM1 lipid raft microdomain, recruiting caveolae-mediated endocytosis as an additional pathway alongside clathrin-mediated endocytosis, thereby increasing the intake of the nanostructure. These findings reframe tumor hyper-sialylation as a determinant of the uptake of anionic nanostructures, such as DNA tetrahedra, and as a targetable parameter for rational optimization of DNA-based nanotherapeutics against cancer.