Using SiO2/PDA-Ag NPs to dual-inhibited photoelectrochemical activity of CeO2-CdS composites fabricated a novel immunosensor for BNP ultrasensitive detection

A novel sandwich photoelectrochemical (PEC) immunosensor was constructed for ultrasensitive brain natriuretic peptide (BNP) detection. In this work, CeO2-CdS was employed as excellent photoactive sensing platform, and SiO2/PDA-Ag nanocomposite was used as signal amplification element. CeO2-CdS, providing great photocurrent response due to the well matched energy band which effectively impeded the recombination of the electrons and holes. For SiO2, due to the poor electro-conductivity and easy modification, it could be well used as an excellent signal-off label. For the sake of improving sensitivity of the immunosensor, Ag nanoparticles (Ag NPs) was applied owing to the energy transfer between CdS, which could decrease the PEC response obviously for amplifying the change of signal value. Besides, Ag NPs could anchor plenty of the detection antibodies by the chemical bonding between Ag NPs and -NH2 of antibodies. Using PDA to connected SiO2 and Ag NPs because of it great biocompatibility and reducing capacity. The well-established PEC immunosensor exhibited a low detection limit of 0.05 pg mL(-1) (S/N= 3) with a linear range from 0.1 pg mL(-1)-5 ngmL(-1) for BNP detection. In addition, the immunosensor also exhibited good stability, satisfactory reproducibility and acceptable specificity, which could be applied to detect other biomarkers.