The invention relates to a process for preparing a conjugate that includes a pentopyranosyl nucleic acid and a biomolecule. The process includes the steps of providing a pentopyranosyl nucleic acid having at least two pentopyranosyl nucleotide subunits that are covalently linked between carbon 4 and carbon 2 of their respective pentopyranosyl rings. The pentopyranosyl nucleic acid also has an electrophilic reactive group. A biomolecule having a nucleophilic reactive group is also provided. The electrophilic reactive group of the pentopyranosyl nucleic acid and the nucleophilic reactive group of the biomolecule are reacted to form a covalent bond.