Sensitive electrochemical immunosensor for the detection of cancer biomarker using quantum dot functionalized graphene sheets as labels

Quantum dot (QD) functionalized graphene sheets (GS) were prepared and used as labels for the preparation of sandwich-type electrochemical immunosensors for the detection of a cancer biomarker (i.e., prostate specific antigen (PSA)). The primary anti-PSA antibody was also immobilized onto the GS. The immunosensor displayed a wide range of linear response (0.005–10 ng/mL), low detection limit (3 pg/mL), and good reproducibility, selectivity and stability. The immunosensor was used to detect PSA in patient serum samples with satisfactory results. Thus, this unique immunosensor may provide many applications in clinical diagnosis.