Under the drive of AS1411, the designed UCNPs@PDL@dsDNA/DOX nanotheranostic agent would be selectively endocytosed into nucleolin overexpressed cancer cells, then the DNA nanotrain would further come into the nucleus where the overexpressed PCNA would selectively recognize and strongly bind with the anti-PCNA aptamer to induce the in situ release of loaded DOX molecules. The gene discussed is PCNA; the disease is cancer.