A sequential dual-locked luminescent copper nanocluster probe for tumor cell imaging and killing.

A sequential dual-locked luminescent copper nanoclusters (CuNCs) probe was designed and synthesized for the specific imaging and selective killing of tumor cells. This nanoprobe was prepared by first forming a Fe 3+ -coupled tannic acid (TA)-stabilized CuNCs (CuNCs-Fe III ), which is in quenching state due to the electron transfer between CuNCs and Fe 3+ , and then coating a protectable layer of hyaluronic acid (HA) on the surface of CuNCs-Fe III to form the final dual-locked nanoprobe (CuNCs-Fe III @HA). When the nanoprobe of CuNCs-Fe III @HA target enter the tumor cells through CD44-HA receptor, HAase will first digest the HA layer of the nanoprobes, and then, GSH over-expressed in tumor cells will reduce Fe 3+ to Fe 2+ , thus restoring the fluorescence emission of CuNCs and at the same time killing the tumor cells with the hydroxyl free radicals (∙OH) produced by the Fenton reaction between Fe 2+ and H 2 O 2 . This sequential dual-locked luminescent nanoprobe of CuNCs-Fe III @HA has been successfully used for the specific imaging and selective killing of tumor cells.