pH-Responsive spherical nucleic acid for intracellular lysosome imaging and an effective drug delivery system.

Herein, a class of pH-responsive spherical nucleic acid (SNA) nanostructures prepared by functionalizing gold nanoparticles with DNA nanodevices is presented, which can perform duplex-to-triplex transition upon pH change via pH-sensitive parallel Hoogsteen interactions. The SNA nanostructures exhibit tunable pH sensitivity and a highly rapid and reversible allosteric effect. Furthermore, they can exactly image lysosomes in living cells. We next engineered pH-triggered doxorubicin(Dox)-SNA conjugates that could deliver Dox molecules into cancer cells and achieve pH-dependent drug release.