I-LinkerTM, developed at IDT, is a proprietary covalent attachment chemistry for oligonucleotides. The modifier is attached to the 5'-end of the oligo. I-LinkerTM can be substituted for amino modifications in many applications. In addition, I-LinkerTM expands the range of reactive groups that can be used for conjugation, including aldehyde and ketone-modified ligands or surfaces.