STRATEGIES FOR DELIVERY

Part I: Endcaps are linkers that link the 3 and 5 §ends of DNA duplexes. A series of diamide endcaps §has been synthesized and shown to stabilize DNA §duplexes (4 base-pair). Endcapped CpG §oligonucleotides were synthesized to elucidate the §mode of recognition of different forms of CpG §oligonucleotides by the immune system. Endcapped CpG §oligonucleotides stimulated IL-6 and IL-12 secretion §and extended the life span of the tumor implanted §mice beyond that of the untreated control mice. §Closed endcapped DNA duplexes were obtained by §enzymatic ligation of the nicked DNA duplexes. The §efficiency of ligation was dependent on the number §of nucleotides flanking the 3 - and 5 ends of the §nick. The nuclease stability of endcapped CpG §oligonucleotides was established to be at least 6-§fold more stable than unmodified oligonucleotides. §Part II: Thiol terminated amine and guanidinium §derivatives were synthesized and conjugated to 5 nm §and 10 nm gold nanoparticles. These functionalized §gold colloids were studied for their cellular uptake.