Chemically Modified Antisense Oligonucleotides—Recent Improvements of RNA Binding and Ribonuclease H Recruitment

The incorporation of rationally designed sugar or nucleobase modifications into oligonucleotides gives remarkable improvements of the antisense activity. For example, the cytosine analogue 1 recognizes both the Watson–Crick and the Hoogsteen site of a guanine nucleotide 2, which dramatically enhances the RNA-binding affinity and selectivity.