One aspect of the present invention relates to a double-stranded oligonucleotide comprising at least one ligand tethered to an altered or non-natural nucleobase. In certain embodiments, the non-natural nucleobase is difluorotolyl, nitropyrrolyl, or nitroimidazolyl. In certain embodiments, the ligand is a steroid or aromatic compound. In certain embodiments, only one of the two oligonucleotide strands comprising the double-stranded oligonucleotide contains a ligand tethered to an altered or non-natural nucleobase. In certain embodiments, both of the oligonucleotide strands comprising the double-stranded oligonucleotide independently contain a ligand tethered to an altered or non-natural nucleobase. In certain embodiments, the oligonucleotide strands comprise at least one modified sugar moiety. Another aspect of the present invention relates to a single-stranded oligonucleotide comprising at least one ligand tethered to an altered or non-natural nucleobase. In certain embodiments, the non-natural nucleobase is difluorotolyl, nitropyrrolyl, or nitroimidazolyl. In certain embodiments, the ligand is a steroid or aromatic compound. In certain embodiments, the ribose sugar moiety that occurs naturally in nucleosides is replaced with a hexose sugar, polycyclic heteroalkyl ring, or cyclohexenyl group. In certain embodiments, at least one phosphate linkage in the oligonucleotide has been replaced with a phosphorothioate linkage.
本发明的一个方面涉及一种双链寡核苷酸,其中至少有一种
配体被系着到改变或非自然的核碱基上。在某些实施例中,非自然的核碱基是二
氟基
甲苯基、硝基
吡咯基或硝基
咪唑基。在某些实施例中,
配体是类
固醇或芳香族化合物。在某些实施例中,只有双链寡核苷酸中的两条寡核苷酸链中的一条包含系着到改变或非自然核碱基上的
配体。在某些实施例中,双链寡核苷酸中的两条寡核苷酸链都独立地包含系着到改变或非自然核碱基上的
配体。在某些实施例中,寡核苷酸链包含至少一个改变的糖基团。本发明的另一个方面涉及一种单链寡核苷酸,其中至少有一种
配体被系着到改变或非自然的核碱基上。在某些实施例中,非自然的核碱基是二
氟基
甲苯基、硝基
吡咯基或硝基
咪唑基。在某些实施例中,
配体是类
固醇或芳香族化合物。在某些实施例中,自然存在于核苷中的
核糖糖基团被替换为六碳糖、多环杂环烷基环或
环己烯基团。在某些实施例中,寡核苷酸中至少有一个
磷酸酯键被
磷酸硫酯键替换。