Boron Clusters − A New Entity for DNA-Oligonucleotide Modification

The carboranyl cluster is a new and versatile modifying entity for nucleotides and nucleic acids. Three types of carboranyl (−C2B10H11) group‐containing DNA‐oligonucleotides are described: (1) CBMP‐oligonucleotides, consisting of the carborane cage within an internucleotide linkage; (2) CDU‐oligonucleotides, containing the carborane cage attached to a nucleobase; and (3) 2′‐CBM‐oligonucleotides, with the carborane cage linked to a sugar residue at the 2′ position. The method of synthesis and the physicochemical and biochemical features of these novel modifications are discussed, together with structure−property relationships. The carboranyl cluster‐containing oligonucleotides form a crossover between (carba)borane chemistry and molecular biology. They are potentially useful as antisense agents for antisense oligonucleotide therapy (AOT) and boron carriers for boron neutron capture therapy (BNCT). The chemistry of carborane‐modified nucleic acids has implications beyond BNCT and AOT. Owing to the unique properties of carborane clusters they have potential for further development as molecular probes for molecular medical diagnostics and bioinorganic material for emerging technologies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)