Covalent tethering of protruding arms for addressable DNA nanostructures

Functionalization of self-assembled DNA nanostructures is of fundamental importance for the realization of their application in nanotechnology and biosensing. Approaches reported so far suffer from lack of general applicability and usually require careful system design to avoid poor yields in the assembly of target structures. A novel approach well suited for fabrication of addressable DNA superstructures is reported here to generate DNA tile motifs. The method is based on the covalent linkage of a single-stranded protruding arm (covPA) to one of the oligomers forming the tile. Subsequent to assembly of tile motifs and superlattices, the covPA can be addressed by hybridization with complementary oligonucleotides or DNA-protein conjugates. The covPA can be located at arbitrary positions in a given tile motif without changing the general design and without compromising the structural integrity of the tile. The covPA strategy can also be readily extended to different PA sequences and multiple covPA arms can be linked to a tile. Superlattices obtained by self-assembly of covPA tiles reveal partial folding into double layers which possess an intrinsic order at the ultrastructural level. This phenomenon is likely associated with the increased flexibility of the covPA and might open up novel ways for DNA-based functionalization of solid surfaces and other applications of structural DNA nanotechnology.