A signal-off type photoelectrochemical immunosensor for the ultrasensitive detection of procalcitonin: Ru(bpy)32+ and Bi2S3 co-sensitized ZnTiO3/TiO2 polyhedra as matrix and dual inhibition by SiO2/PDA-Au

Abstract

A signal-off type photoelectrochemical (PEC) immunosensor based on Ru(bpy)32+ and Bi2S3 co-sensitized ZnTiO3/TiO2 polyhedra as matrix and SiO2/PDA-Au as the label of second antibody was proposed for the ultrasensitive detection of procalcitonin (PCT). The hollow ZnTiO3/TiO2 polyhedra called zinc titanium composite hollow structures (ZTCHS) was prepared by hydrothermal method to enhance the utilization of visible light comparing with pure ZnTiO3 or TiO2. The unique structure endowed large specific surface areas and satisfying load capacity to ZTCHS. Ru(bpy)32+ and Bi2S3 were utilized to co-sensitize ZTCHS to further strengthen the PEC performance of ZTCHS. It was interesting that the dual-inhibition effects of SiO2/PDA-Au further enhanced the sensitivity of proposed PEC immunosensor. On the one hand, the steric hindrance of SiO2/PDA effectively restricted electron transfer. On the other hand, Au nanoparticles could absorb visible light to compete with the matrix material. Based on the above aspects, the proposed signal-off type PEC immunosensor possessed a wide linear range from 0.0001 ng mL−1 to 100 ng mL−1 and low detection limit (about 0.03 pg mL−1, S/N = 3), demonstrating the promising application of PEC immunosensor in analysis fields.