Provided herein are cell penetrating conjugates. The conjugates include a non-cell penetrating protein attached to a phosphorothioate nucleic acid or phosphorothioate polymer backbone through a non-covalent linker including abiotin-binding domain and a biotin domain, wherein the phosphorothioate nucleic acid or phosphorothioate polymer backbone enhances intracellular delivery of the non-cell penetrating protein. Also provided are compositions and kits comprising the conjugates.