Multifunctional near-infrared-emitting nano-conjugates based on gold clusters for tumor imaging and therapy.

Gold nanoclusters (NCs) were functionalized as a fluorescent probe and a pro-drug intended for tumor diagnosis and therapy. Firstly, Au NCs were conjugated with methionine (Met) and MPA, a near-infrared (NIR) fluorescent dye, giving a probe, Au-Met-MPA. The tumor targeting capability endowed by Met as well as low cytotoxicity of this contrast agent and its clinical potential for tumor targeting imaging were demonstrated in vitro and in vivo. Secondly, Doxorubicin (DOX), a widely used clinical anti-cancer drug, was immobilized on the methionine modified Au NCs to form a pro-drug, Au-Met-DOX. The enhanced tumor affinity and improved anti-tumor activity of this pro-drug were demonstrated. Results in this study suggest not only the prospect of non-toxic Au NCs modified with functional ligands for tumor-targeted imaging, but also confirm the promising future of Au NCs as a core for the design of pro-drug in the field of cancer therapy.