Enhanced chemiluminescence by Au-Ag core-shell nanoparticles: A general and practical biosensing platform for tumor marker detection

A general and practical chemiluminescence (CL) biosensing platform for detection of tumor marker prostate-specific antigen (PSA) as a model analyte was developed for the first time based on the excellent catalytic performance of bimetallic Au-Ag core-shell nanoparticales (Au@Ag NPs) on luminol-K3Fe(CN)6 CL system. The Au@Ag NPs were synthesized by a simple and green aqueous phase successive reduction method. The prepared Au@Ag NPs with remarkable synergistic catalytic activity effect could significantly catalyze luminol-K3Fe(CN)6 CL reaction to produce a great CL enhancement. Based on this synergistic catalytic activity, a luminol-K3Fe(CN)6-Au@Ag NPs CL system combined with immunoassay was designed for the sensitive detection of PSA. In this protocol, the Au@Ag NPs were modified with anti-PSA-antibody (Ab-Au@Ag NPs) to specifically capture target molecules PSA. In the presence of PSA, a non-competitive immunoreaction occurred between Ab-Au@Ag NPs and PSA to form an immnunonanoshperes (PSA-Ab-Au@Ag NPs). The results show that the CL catalytic ability of the immnunonanospheres decreased with the PSA concentration increasing. And the quenching degree of CL signals is proportional to the logarithm of PSA concentration in the range of 0.1 pg mL−1-100.0 ng mL−1. Thanks to the fine performance of the Au@Ag NPs, the detection limit of the method is down to 0.047 pg mL−1 (S/N = 3). Moreover, the applicability of the present method was successfully applied for PSA determination in human serum samples with recoveries of 86.1-112.5%, demonstrating great promise for application in biochemical analysis.