Glutathione-capped fluorescent gold nanoclusters for dual-modal fluorescence/X-ray computed tomography imaging

The development of efficient multifunctional nanoprobes for tumour imaging has become a great challenge. Herein, we report for the first time the synthesis of folic acid (FA)-conjugated glutathione (GSH)-capped gold nanoclusters (Au NCs) for dual mode fluorescence/X-ray computed tomography imaging of gastric cancer. Water-soluble GSH-capped Au NCs were synthesized by using tetrabutylammonium borohydride (TBAB) as the reducing agent, and was characterized by transmission electron microscopy, UV-vis absorption spectroscopy, fluorescence spectroscopy, and X-ray photoelectron spectroscopy. The AuNCs@GSH showed excellent photoluminescence properties and negligible cytotoxicity at a concentration as high as 200 μg mL^-1. Folic acid was covalently anchored to the AuNCs@GSH; the nanoprobe showed highly selective targeting of the gastric cancer MGC-803 cells revealed by laser scanning confocal microscopy (LSCM). Hematoxylin and eosin (HE) staining results showed that AuNCs@GSH displayed no toxicity to important organs. In conclusion, the FA-conjugated AuNCs@GSH nanoprobe can be used for gastric cancer fluorescence imaging and X-ray computed tomography (CT) imaging. Therefore, the applications of AuNCs@GSH could be extended and bring more benefits to nanotechnology as an ideal biomedical platform.