title: Unilamellar liposomes with enhanced boron content.
abstract: A new type of boron-rich, DSPC-free, unilamellar liposomes was formed using the novel dual-chain, ionic, nido-carborane lipid, K[nido-7-(C16H33OCH2)2CHOCH2-7,8-C2B9H11] (DAC-16), and cholesterol for encapsulation of an aqueous buffer core. Since DSPC was not necessary for the formation of stable DAC-16 liposomes, the boron concentration of these vesicles was increased dramatically to approximately 8.8 wt % in the dry lipid; these liposomes had a high bilayer boron incorporation efficiency of 98%. DSPC-free liposomes exhibited a size distribution pattern of 40-60 nm, which was in the range normally associated with selective tumor uptake. This size distribution was maintained throughout storage at room temperature for several months. Additionally, optimized liposome formulations incorporating DAC-16, DSPC, and cholesterol were identified having stable size distribution patterns after storage for more than two months at a variety of temperatures. Although animal studies indicate that DAC-16 liposomes are toxic, this new ionic nido-carborane lipid allows the formation of liposomes of high boron content for in vitro applications that require the delivery of large amounts of boron.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, USA.
authors.forename: Tiejun
authors.initials: T
authors.lastname: Li
authors.forename: Julie
authors.initials: J
authors.lastname: Hamdi
authors.forename: M Frederick
authors.initials: MF
authors.lastname: Hawthorne
mesh_terms: D000818:Animals; D001880:Boranes / Q000008:administration & dosage / Q000737:chemistry* / Q000633:toxicity; D016754:Boron Neutron Capture Therapy; D008081:Liposomes / Q000008:administration & dosage / Q000138:chemical synthesis* / Q000633:toxicity; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D023382:Toxicity Tests, Acute
chemical_list: D001880:Boranes; D008081:Liposomes