Sensitive photoelectrochemical sensor for detection of cancer biomarker based on enzyme embedded nanoparticles as signal probe.

• Photoelectrochemical immunosensor for detection of cancer biomarker. • Organic semiconductor Y6 and gold nanoparticles were utilized as photoactive material. • ZnPO 4 nanoparticles with horseradish peroxidase embedded was used as signal probe. • Horseradish peroxidase catalyzed the formation of insulating film on electrode. • The insulating film resulted in suppression of photoelectrochemical current intensity. Photoelectrochemical (PEC) sensor was prepared for detection of cancer biomarker carcinoembryonic antigen (CEA), which is strongly associated with diagnosis and prognosis of different cancer. Organic semiconductor Y6 combined with gold nanoparticles (Au NPs) formed organic–inorganic heterojunction and the heterojunction was utilized as photoactive material. ZnPO 4 nanoparticles with horseradish peroxidase (HRP) embedded inside the nanoparticle and antibody absorbed on nanoparticle surface were synthesized and utilized as signal probe. After formation of sandwich structure on electrode surface, HRP can catalyze 3,3′-dimethoxybenzidine (DB) in solution to form insulating polymer film, poly(3,3′-dimethoxybenzidine) (PDB) onto the electrode surface. The formed PDB film on electrode surface resulted in the suppression of PEC current intensity, achieving sensitive and selective detection of CEA with linear range from 1 pg/mL to 1 ng/mL and limit of detection of 0.5 pg/mL. [ABSTRACT FROM AUTHOR]