New Non Nucleosidic Phosphoramidites for the Solid Phase Multi-Labelling of Oligonucleotides: Comb- and Multifork-Like Structures

Comb- and multifork-like structures have been designed for multiple labelling of oligonucleotides. They rely on the synthesis of new non nucleosidic phosphoramidites which can be used in automatic DNA synthesis. The new compounds allowed the 5′ and/or 3′ tagging of any oligonucleotide and provided reactive primary amino groups for non isotopic labelling. Seventeen polybiotinylated oligonucleotides have been prepared and tested in hybridization assays using a corresponding complementary sequence covalently linked to polystyrene tubes. Detection limits, measured by chemiluminescence, ranged from 105 to 3.106 molecules, depending on the number of biotins. Optimal detection was achieved either with a 5′ multifork-like derivative carrying 8 biotins or with a comb-like structure carrying 4 biotins on both 5′ and 3′ ends.