DNA Nanotechnology and Drug Delivery - DNA Nanotechnology: From Structure to Function - page 314

Fig. 15.3 Flow cytometry
analysis of the efficiency and
stability of transfection with
fluorescently labeled DNA
cages. The mean fluorescence
per cell is similar for cells
transfected with and without
Lipofectin and is constant for
at least 72 h. Control: mock
transfection without
tetrahedra (Reprinted with
permission from Ref. [ 10 ].
Copyright 2011 American
Chemical Society)
Fig. 15.4 Schematic showing the assembly of CpG bearing DNA tetrahedron and its immunos-
timulatory effect (Reprinted with permission from Ref. [ 11 ]. Copyright 2011 American Chemical
Society)
Building on the success of the previous works, Fan's group then studied the
application of this DNA tetrahedron structure as a real drug delivery nanocarrier
[ 11 ]. They attached unmethylated cytosine-phosphate-guanine (CpG) motifs to their
DNA tetrahedron structure to make it highly immunostimulatory. Once getting into
the cells, the therapeutic CpG oligodeoxynucleotides will bind the Toll-like receptor
9 (TLR9) and allosterically activates TLR9, which then activates downstream
pathways to induce immunostimulatory effects, producing high-level secretion
of various proinflammatory cytokines including tumor necrosis factor (TNF)-R,
interleukin (IL)-6, and IL-12. Because of the advantage of the programmability of
DNA nanostructures, they were able to selectively attach different numbers (one to
four) CpG motifs to one DNA tetrahedron structures (Fig. 15.4 ,Ref.[ 11 ]).
In order to study the cellular uptake efficacy of their functional DNA tetrahedron
structure, they also labeled at one position of the DNA tetrahedron with the organic
fluorescence dye, TAMRA. After incubating the TAMRA-labeled CpG-DNA tetra-
hedron structures with macrophage-like RAW264.7 cells, consistent with previous
findings [ 10 ], their results showed that the DNA tetrahedron structures could
noninvasively and efficiently enter macrophage-like RAW264.7 cells without the