Fig. 3

a A standard curve of DOX concentrations in PBS buffer; λex = 480 nm and λem = 590 nm. The amount of DOX carried by the TDN and Apt-TDN. b DOX intercalated into the double-strand DNA of the TDN and Apt-TDN. When the DOX concentration reached 14 μM and the intercalated DOX concentration in the TDN and Apt-TDN peaked at 5.5 μM and 6.0 μM, respectively, a single DNA tetrahedron could carry 55 Dox molecules, while a single aptamer-modified DNA tetrahedron carried 60 DOX molecules. c Fluorescence spectra of DOX in the supernatant. Doxorubicin was mixed with the TDN at increasing molar ratios (0, 0.0005, 0.001, 0.005, 0.01, and 0.05 from top to bottom). When the molar ratio was 1:20, the fluorescence was quenched