A label-free electrochemiluminescence immunosensor based on KNbO3-Au nanoparticles@Bi2S3 for the detection of prostate specific antigen

A high sensitive label-free electrochemiluminescence (ECL) immunosensor was fabricated for the detection of prostate specific antigen (PSA) based on potassium niobate-Au nanoparticles@bismuth sulfide (KNbO3-Au NPs@Bi2S3) modified glassy carbon electrode (GCE). The prepared Bi2S3 nanosheets exhibited strong and stable cathodic ECL activity. The synthesized KNbO3-Au NPs was firstly used to fabricate ECL modified electrodes and Bi2S3 nanosheets worked as luminophores for the first time in ECL sensors. Au NPs were used to combine with Bi2S3 and anti-PSA via the Au-S covalent bond and Au-NH2 covalent bond without the usage of crosslinking agents respectively, further enhancing the sensitivity and stability of immunosensor. Under the optimum experimental conditions, the ECL signal of KNbO3-Au NPs@Bi2S3 linearly decreased with the increase of PSA concentration in the range of 0.005-5 ng/mL with a detection limit of 3 pg/mL. The preparated label-free ECL immunosensor exhibited high sensitivity and selectivity, good repeatability and long-term stability. The applicability of the proposed ECL immunosensor was also evaluated by detecting PSA in real samples.