Source:Biosensors and Bioelectronics, Volume 96
Author(s): Xueping Wang, Rui Xu, Xu Sun, Yaoguang Wang, Xiang Ren, Bin Du, Dan Wu, Qin Wei
An ultrasensitive sandwich-type photoelectrochemical (PEC) immunosensor was constructed for the detection of prostate specific antigen (PSA). In this work, Au-nanoparticle-loaded tungsten oxide (WO3-Au) hybrid composites was applied as PEC sensing platform, while Ca ions doped CdSe equipped on the conducting framework of reduced graphene oxide (rGO-Ca:CdSe) nanocomposites were employed as the signal amplification probe. As for WO3-Au, massive Au nanoparticles were formed on the surface of WO3 without any additional reducing agent, providing a novel nanocarriers for anchoring plenty of the primary antibodies due to the large specific surface area and good biocompatibility by chemical bonding between Au nanoparticles and -NH2 of antibodies. Besides, the incorporation of the rGO and the doping of Ca ions could improve the conductivity and hinder the recombination of electron-hole pairs of CdSe nanoparticles effectively, thereby enhancing the photocurrent conversion efficiency. Based on the sandwich immunoreaction, the primary antibody was immobilized onto WO3-Au substrate, after the formed rGO-Ca:CdSe labels were captured onto the electrode surface via the specific antibody-antigen interaction, the photocurrent intensity could be further enhanced due to the sensitization effect. Under the optimal conditions, the proposed PEC immunosensor shows a linear relationship between photocurrent variation and the logarithm of PSA concentration in the wide range of 5pgmL−1 to 50ngmL−1 with a low detection limit of 2.6pgmL−1 (S/N=3). Moreover, it also presented good stability and acceptable specificity, indicating the potential applications in clinical diagnostics.
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