High luminous efficiency Au@CDs for sensitive and label-free electrochemiluminescent detection of circulating tumor cells in serum

In this work, new gold@carbon dots nanoalloys (Au@CDs) were synthesized by directly heating carbon dots (CDs) and HAuCl4 aqueous solution to boiling. The as-synthesized Au@CDs exhibited 12-fold enhancement in the ECL emission compared to the single CDs. The high luminous efficiency Au@CDs was further used to fabricate an ECL cytosensor for the direct detection of circulating tumor cells (CTCs) in serum by ligation of a cell-specific aptamer. Briefly, human mucin1 protein (MUC1) aptamer was immobilized onto the surface of Au@CDs on the electrode for capturing MUC1-positive MCF-7 cells (a type of CTCs). On the basis of the increased steric hindrance, the captured MCF-7 cells can be quantitatively detected. Our strategy was free from complicated separation and labeling treatment, and realized the detection of MCF-7 cells (a type of CTCs) from 100 to 10,000 cells/mL with a detection limit of 34 cells/mL, offering promising applications in ultrasensitive routine clinical analysis and point-of-care testing.