This part is associated with N15 Protelomerase devices
N15 Protelomerase comes from Bacteriophage N15, a virus-like organism that infects E. coli. The special thing about this organism is that it has a linear DNA--well, kindov. The ends of the DNA are special telomere-like sequences that form hairpins. So, there is no sticky end on their genome, the whole genome is just one big self-complementary circular DNA. The elements that make the DNA form this structure are N15 Protelomerase and the cis element it acts upon, called tos. When present in a normal plasmid DNA, tox sites can be cleaved by protelomerase resulting in the terminally-hairpinned linear DNA.
For our purposes, a device along these lines will help get the DNA into the nucleus of the target organism.
You should read the following papers
References: PMID 17988739, PMID 12395149