Branched tris-DNA, in which two oligonucleotides of the same sequence and one other oligonucleotide of a different sequence are connected with a rigid central linker, was prepared chemically by using a DNA synthesizer. Two branched tris-DNA molecules with complementary DNA sequences form dimer and tetramer as well as linear and spherical oligomer complexes. The complex formation was studied by UV/thermal denaturation, enzyme digestion, gel electrophoresis, and AFM imaging.

We have designed a new type of a DNA dendrimer which has rigid branched structure. The branching molecule was prepared from 1,3,5-tribromobenzene. The dendrimer unit, in which three oligonucleotide-chains, two molecules of TIB and one molecule of AIB, linked to the branching molecule, was synthesized by an automated DNA synthesizer. The properties of the dendrimer unit and dendrimer formation by inter-molecular association of T15 and A15 chains of the dendrimer unit will be presented.