Anticancer luminescent gold quantum clusters for in situ cancer-selective marking-imaging-targeting

Ultrafine Au quantum clusters (QCs) were synthesized by etching host Au nanoparticles in the presence of ethylenediamine (en) and exhibited both strong photoluminescence (PL) and specific anticancer activity. The cutting-edge feature of this QC compound comprises subnanometer-size rhombohedral Au₈, which consists of 8 units of the anticancer motif, namely, an Au⁺(en) complex (Au(en)QCs), which contributes to photo- and physicochemical stability as well as subcellular theranostic activity in intracellular PL imaging and in situ targeting. Moreover, the Au(en)QCs can be surface-encapsulated by transferrins (Tf) to create TfAu(en)QCs as a multipurpose drug carrier owing to numerous merits, which include cancer-selective biolabeling, high loading/release efficiency, high activity against drug-resistant tumor cells, low toxicity to normal cells, and physiological stability against biothiols, e.g., glutathiones. These versatile features, which are due to intrinsic optical and anticancer properties, provide potential as a single-drug delivery PL probe for preclinical applications, which has yet to be achieved using conventional nanoclusters.