Nucleolin specific aptamer and use thereof

Nucleolin-specific aptamer, wherein the aptamer has the sequence of SEQ ID NO:

• 3, and two thymidines(T) present at at least 12th and 13th positions of the nucleotide sequence are independently substituted with a modified pyrimidine nucleoside, and wherein the modified pyrimidine nucleoside is deoxyuridine(dU), deoxycytidine(dC), uridine(U), or cytidine(C) having a hydrophobic group at 5 position:
• NGGTGGTGGTGGTTGTGGTGGTGGTGGN
• (SEQ ID NO:
• 3)
• wherein each N is absent or 1 to 20 nucleosides, which is independently selected from the group consisting of adenosine(A), thymidine(T)/uridine(U), cytidine(C), and guanosine(G), and the positions are counted starting from ‘G’ immediately following ‘N’ at 5′-end,
• wherein the hydrophobic group is selected from the group consisting of a benzyl group, a naphthyl group, or a pyrrolebenzyl group.