Figure 1.

Toll-like receptor 9 (TLR9) activation by CpG and DNA-based disk for delivery of CpG-ODNs. (a) Representation of TLR9 activation with crystal structures of monomer of TLR9 (inactive form) and CpG-bound TLR9 dimer (active form) at binding stoichiometry TLR9:CpG 2:2. PBD codes: 3wpf (monomer), 5zln (dimer with CpG), 4om7 (cytosolic domain). (b) Representation of immune cell activation upon uptake of free CpG-ODNs. Surface markers analyzed in this study are reported. (c) Transmission electron microscopy image of a DNA origami disk and schematic representation (top right corner). Scale bar: 100 nm. (d) Confocal microscopy images, overview (left) and zoom-in (right), of the uptake of Cy5-labeled disks by RAW 264.7 cell line. Nuclei stained with DAPI (blue), late endosome marker (RAB7) in green and Cy5-disks in red. Cells were treated with DNase I after uptake to remove noninternalized DNA structures binding to the cell surface, as previously reported.²² Scale bars: 10 μm.