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 ([email protected] NPs) on luminol-K₃Fe(CN)₆ CL system. The [email protected] NPs were synthesized by a simple and green aqueous phase successive reduction method. The prepared [email protected] 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[email protected] NPs CL system combined with immunoassay was designed for the sensitive detection of PSA. In this protocol, the [email protected] NPs were modified with anti-PSA-antibody ([email protected] NPs) to specifically capture target molecules PSA. In the presence of PSA, a non-competitive immunoreaction occurred between [email protected] NPs and PSA to form an immnunonanoshperes ([email protected] 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 [email protected] 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.