Collard-like Bi₂S₃@Au nanocomposites-based label free electrochemical immunosensor for quantitative detection of...

Here, a label-free immunosensor was conducted using rGO/Collard-like Bi₂S₃@Au nanocomposite system to detect carbohydrate antigen 19-9 (CA19-9) as a diagnostic biomarker for Pancreatic cancer. The unique morphology of Collard-like Bi₂S₃ increases its specific surface area, which allows it to immobilize more materials and biomolecules on its surface. To realize the covalent bonding of bismuth-based materials with biomolecules, bismuth-based materials were functionalized by Au NPs. Besides, the superior electrochemical activity and large specific surface area of Bi₂S₃@Au improved the stability of the sensor, which made it an ideal candidate for regulating the sensing interface in this study. Meanwhile, reduced graphene oxide (rGO) with remarkable electrical conductivity to improve the current response of the sensing interface, thus broadening the linear range of the immunosensor. Based on the above materials, a label free electrochemical immunosensor was constructed for detecting CA19-9. Under optimal conditions, it displays good linear relationship within the range of 0.01 U mL^-1 to 100 U mL^-1, the detection limit being 0.0012 U mL^-1. Additionally, the immunosensor prepared in this work is characterized by superior interference immunity, reproducibility and storage stability, and has yielded satisfactory recovery rate in testing the serum samples of patients.