▎ 摘　　要

Determination of circulating cancer cells in human blood is potential to be convenient diagnosis of different cancers. The study reports one strategy for synthesis of folic acid and glutamic acid-functionalized graphene quantum dot-palladium@gold (FA/Glu-GQD-Pd@Au). Firstly, FA/Glu-GQD was prepared by thermolysis of the mixture of citric acid, glutamic acid and folic acid. Then, it was used as the stabilizer and reducer for synthesis of FA/Glu-GQD-Pd@Au. The resulting hybrid was employed as one redox probe for construction of electrochemical sensing platform for cancer cells. The study reveals that the FA/Glu-GQD-Pd@Au offers one core@shell nanostructure. Pd nanocube as the core was covered by gold nanocrystal as the shell. For the detection, Pd@Au gives high electrocatalytic activity due to its unique structure as well as combination with FA/Glu-GQD. FA/Glu-GQD strongly binds with cancer cells to produce target recognition. FA/Glu-GQD occurs reversible redox reactions on the electrode surface and produces electrochemical signal for binding cancer cells. Pd@Au in situ catalyzes redox of FA/Glu-GQD and achieves to significant signal amplification. The sensor based on FA/Glu-GQD-Pd@Au exhibits ultrahigh sensitivity for detection of cancer cells. The differential pulse voltammetric peak current linearly reduces with the increase of cancer cells in the range of 3-1 x 10(5) HepG2 cells mL(-1) with the detection limit of 2 cells mL(-1) (S/N = 3). The proposed analytical method has been successfully applied in electrochemical detection of circulating cancer cells in human blood.