Provided herein are oligonucleotides, cell penetrating peptides, and peptide-oligonucleotide-conjugates. Also provided herein are methods of treating a muscle disease, a viral infection, or a bacterial infection in a subject in need thereof, comprising administering to the subject oligonucleotides, peptides, and peptide-oligonucleotide-conjugates described herein.本發明提供寡核苷酸、細胞穿透肽及肽-寡核苷酸結合物。本發明亦提供治療有需要之受試者之肌肉疾病、病毒感染或細菌感染之方法,該方法包含向該受試者投與本文中所描述之寡核苷酸、肽及肽-寡核苷酸結合物。