Poly(dopamine) coated gold nanocluster functionalized electrochemical immunosensor for brominated flame retardants using multienzyme-labeling carbon hollow nanochains as signal amplifiers

An electrochemical, signal amplified immunosensor was developed to detect 3-bromobiphenyl (BBP) by using a bio-inspired polydopamine (PDOP)/gold nanocluster (AuNc) as the sensor platform and multienzyme-labeled carbon hollow nanochains as the signal amplifier. The self-polymerized dopamine membrane on the AuNc-modified indium tin oxide (ITO) electrode were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle and electrochemical measurements. Such PDOP/AuNc platform featured the mild cross-linking reaction with the dense immobilization of BBP-antigens (BBP-Ag). Moreover, by using multiple horseradish peroxidase (HRP) and secondary antibodies (Ab 2 ) modified one-dimensional carbon hollow nanochains (CHNc) as the signal enhancer, it held promise for improving the sensitivity and detection limit of the immunoassay . Based on the competitive immunoassay protocol, this immunosensor showed a linear range from 1   pM to 2   nM for BBP with a detection limit of 0.5   pM. Also, it exhibited high sensitivity, wide linear range, acceptable stability and reproducibility on a promising immobilization platform using a novel signal amplifier, which may extend its application in other environmental monitoring.