In 2017, Zhang’s group conjugated the nucleolar aptamer and PTX with a stable cathepsin B-sensitive dipeptide linker to form an aptamer–PTX conjugate with high aqueous solubility, prodrug transmittability, and tumor inhibition (shown in Figures 9, 10), which gathered target-specific binding affinity derived from the aptamer and cytotoxicity generated by PTX. Here, CTSB is linked to neoplasm.