▎ 摘　　要

Breast cancer is regarded as the most common cause of death after lung cancer among women. Using graphene quantum nanoparticles (GQNPs) to construct a biosensor increases the sensitivity, rapidness, and flexibility of biological tests to detect cancer cells. In this study, we developed a fluorescence immunosensor based on GQNPs and magnetic nanoparticles (MNPs) for selective detection of HER2-positive breast cancer. The GQNPs and MNPs were conjugated with Herceptin individually which was confirmed by physicochemical studies. Then, the conjugates were exposed to the SK-BR3 breast cancer cells to form a sandwich structure of MNP-Herceptin-SK-BR3 cell-Herceptin-GQNP. Then, an inverted fluorescence microscope was used to detect breast cancer cells after isolating them using a magnet. The results showed a high sensitivity (even one cell ml- 1) and specificity of the designed biosensor for the detection of SK-BR3 cells within 30 min.