Nucleic Acids Research 2002-11-01

Hydrazide oligonucleotides: new chemical modification for chip array attachment and conjugation.

Stefan Raddatz, Jochen Mueller-Ibeler, Joachim Kluge, Ludger Wäss, Gerhard Burdinski, John R Havens, Tom J Onofrey, Daguang Wang, Markus Schweitzer

Index: Nucleic Acids Res. 30(21) , 4793-802, (2002)

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Abstract

We report the synthesis of new phosphoramidite building blocks and their use for the modification of oligonucleotides with hydrazides. The reaction of these hydrazide oligonucleotides with active esters and aldehydes is demonstrated for solution conjugation and immobilization. Compared with the established amino modified oligonucleotides, hydrazides show enhanced reactivity at neutral and acidic buffer conditions. One method to introduce hydrazides is using amidites with preformed, protected hydrazides. A completely novel approach is the generation of the hydrazide functionality during the oligonucleotide cleavage and deprotection with hydrazine. Therefore, building blocks for the introduction of esters as hydrazide precursors are described. For the enhanced attachment on surfaces branched modifier amidites, which introduce up to four reactive groups to the oligonucleotide, are applied. The efficiency of branched hydrazide oligonucleotides compared with standard amino modified oligonucleotides for the immobilization of DNA on active electronic Nanogen chips is demonstrated.