Ultrasensitive electrochemical immunosensor for carbohydrate antigen 72-4 based on dual signal amplification strategy of nanoporous gold and polyaniline-Au asymmetric multicomponent nanoparticles

A sandwich electrochemical immunosensor is described for carbohydrate antigen 72-4 (CA72-4) based on a dual amplification strategy with nanoporous gold (NPG) film as the sensor platform and polyaniline-Au asymmetric multicomponent nanoparticles (PANi-Au AMNPs) as labels. In this study, the second anti-CA72-4 antibody (Ab(2)) adsorbed onto the Au of the PANi-Au AMNPs, which could be simply synthesized by interfacial reaction and have many characteristics of polyaniline and Au nanoparticle, such as well-controlled size, high conductivity, biocompatibility and catalysis. NPG film was used as electrode substrate material to fix a large number of antibodies, due to its unique properties: good biocompatibility, high conductivity, large surface area, and stability. The synergetic of NPG film and PANi-Au AMNPs could increase signal response, and significantly improve sensitivity of the immunosensor. The proposed immunosensor exhibited a wide linear range from 2 to 200 U/mL, with a detection limit of 0.10 U/mL CA72-4, good reproducibility, selectivity and stability. This new type of labels for immunosensors may provide many potential applications in the detection of carbohydrate antigen in immunoassays. (C) 2014 Elsevier B.V. All rights reserved.