Synthesis and Properties of Oligonucleotides Carrying Isoquinoline Imidazo[1,2-a]azine Fluorescent Units

Oligonucleotides carrying novel fluorescent compounds with a dipolar isoquinoline imidazo[1,2-a]azine core were prepared. Analysis of the melting curves demonstrates that DNA duplexes carrying these fluorescent labels at their ends have a slight increase in DNA duplex stability. The UV absorption and fluorescent properties of the oligonucleotide conjugates were analyzed. The fluorescent label is sensitive to duplex formation, as cooperative melting curves are also observed at 366 nm and fluorescence has a large increase upon denaturation. Cell uptake studies allow observation of these fluorescently labeled oligonucleotides internalized into HeLa cells.This study was supported by the “Dirección General de Investigación Científica y Técnica” (grant BFU2007-63287, CTQ2010-20541 and CTQ2009-07758), and the Generalitat de Catalunya (2009/SGR/208). N. K. thanks the DGICYT for Ph.D. fellowship.Peer reviewe