Electrochemical immunosensor based on metal ions functionalized CNSs@Au NPs nanocomposites as signal amplifier for simultaneous detection of triple tumor markers

A multiple immunosensor was developed for simultaneous detection of prostate specific antigen (PSA), carcinoembryonic antigen (CEA) and α-fetoprotein (AFP). In this sensing platform, metal ions functionalized gold nanoparticles-carbon nanospheres (CNSs@Au NPs) nanocomposites were firstly synthesized not only as an efficient immunoprobe but also as signal amplifier. Herein, CNSs@Au NPs with large specific surface area and excellent biocompatibility provided a good vehicle to load much more second antibodies. Metal ions (Pb 2+ 、Cd 2+ 、Zn 2+ ) were fixed the surface of nanocomposites via strong binding capacity with amino-groups of second antibodies to form a signal amplifying system. Meanwhile, immunosensor was prepared by depositing Au NPs and coating primary antibodies on the glassy carbon electrode. In the existence of target analytes and immunoprobes, the immunosensor could simultaneously respond to multiple analyte targets and three distinguishable signal peaks of square wave voltammetry (SWV) were obtained. Under appropriate experimental conditions, the proposed immunosensor exhibited wider measurement linear ranges for three markers (PSA, 0.01 to 100 ng mL −1 , CEA and AFP, 0.01 to 80 ng mL −1 ) with a low detection limits of PSA (3.6 pg mL −1 ), CEA (3.0 pg mL −1 ) and AFP (2.6 pg mL −1 , S/N = 3). Finally, the as-prepared immunosensor was assessed with human serum samples. Compared with the reference method, no obvious difference was observed, indicating our immunosensor had a potential application in early clinical diagnosis of tumor markers.