Facile fabrication of visible light photoelectrochemical immunosensor for SCCA detection based on BiOBr/Bi2S3 heterostructures via self-sacrificial synthesis method

A novel visible light photoelectrochemical immunosensor based on BiOBr/Bi2S3 heterostructures was fabricated to detect squamous cell carcinoma antigen (SCCA). Bi2S3 nanoparticles formed on the BiOBr microflowers by the self-sacrificial synthesis method based on the facile reaction between BiOBr and S2- ions. The BiOBr/Bi2S3 composites exhibited excellent visible light photoelectrochemical activity, when ascorbic acid (AA) was employed as a perfect electron donor. The photocurrent intensity of BiOBr/Bi2S3 modified ITO electrode arrived at around 20 µA, which was approximately 30 times than that of pure BiOBr. Dopamine formed easily polydopamine film via self-polymerization on the surface of BiOBr/Bi2S3 composites to immobilize SCCA antibody. Under the optimal condition, this photoelectrochemical immunosensor realized the ultrasensitive determination of SCCA. With the logarithm of SCCA concentration in the range of 0.001–75 ng mL−1, the specific binding between SCCA and antibody led to the linearly decrease of photocurrent signal with a low detection limit of 0.3 pg mL−1 (S/N = 3). This facilely constructed photoelectrochemical immunosensor maybe have promising practical application in photocatalysis, analytical detection and biosensor, etc.