Ultrasensitive Photochemical Immunosensor Based on Flowerlike SnO₂/BiOI/Ag₂S Composites for Detection of Procalcitonin

Based on the necessity and urgency of detecting infectious disease marker procalcitonin (PCT), a novel unlabeled photoelectrochemical (PEC) immunosensor was prepared for the rapid and sensitive detection of PCT. Firstly, SnO₂ porous nanoflowers with good photocatalytic performance were prepared by combining hydrothermal synthesis and calcining. BiOI nanoflowers were synthesized by facile ultrasonic mixed reaction. Ag₂S quantum dots were deposited on SnO₂/BiOI composites by in situ growth method. The SnO₂/BiOI/Ag₂S composites with excellent photoelectric properties were employed as substrate material, which could provide significantly enhanced and stable signal because of the energy level matching of SnO₂, BiOI and Ag₂S and the good light absorption performance. Accordingly, a PEC immunosensor based on SnO₂/BiOI/Ag₂S was constructed by using the layered modification method to achieve high sensitivity analysis of PCT. The linear dynamic range of the detection method was 0.50 pg·mL^-1~100 ng·mL^-1, and the detection limit was 0.14 pg·mL^-1. In addition, the designed PEC immunosensor exhibited satisfactory sensitivity, selectivity, stability and repeatability, which opened up a new avenue for the analyzation of PCT and further provided guidance for antibiotic therapy.