Highly loaded nanoparticulate carrier using an hydrophobic antisense oligonucleotide complex

Antisense oligonucleotides, and particularly those with phosphorothioate ba ckbones, have emerged as potential gene specific therapeutic agents and are currently undergoing evaluation in clinical trials for a variety of diseas es. In the area of HIV-I therapeutics, targeting of oligonucleotides to inf ected cells, such as macrophages, would be highly desirable. The present st udy was designed to prepare and characterize oligonucleotide-loaded nanopar ticles for this purpose. Due to their hydrophilic characteristics, oligonuc leotides are difficult to entrap in polymeric particles. Here, the oligonuc leotides were first complexed with cetyltrimethylammonium bromide. The olig onucleotide-loaded nanoparticles were prepared by the emulsification-diffus ion method and subsequently purified. In comparison with previous studies, a high oligonucleotide-loading was achieved: 2.5, 5 and 10% oligonucleotide loading were assessed. If the initial oligonucleotide content was 4%, this method produced a final oligonucleotide loading of 1.9% with an entrapment efficiency of 47%. The integrity of the oligonucleotide and of the polymer , in the final freeze-dried product, was retained. (C) 1999 Elsevier Scienc e B.V. All rights reserved.