作者： Kaiyang Chena1，Jiyang Xueb1，Qing Zhoua，Yue Zhanga，Mingming Zhanga，Yuanjian Zhanga，Hai Zhangb，Yanfei Shena

aMedical School, School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 210009, China

bDepartment of Pharmacy, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, 201204, China

摘要：A “signal-on” photoelectrochemical (PEC) immunosensor for highly sensitive detection of Human Epididymis Protein 4 (HE4), a new serum biomarker of ovarian cancer with small molecular weight, was fabricated by coupling the porphyrin-based metal-organic framework (MOF) nanosphere (nPCN-224) and Nanobody (Nb). To label the Nb, the nPCN-224 with an average size of 160–200 nm was prepared by solvothermal method. The mechanism for the photocurrent generation of nPCN-224 was systematically investigated, showing that the dissolved O2 in aqueous solution participated in the charge separation and transport during the photoelectric conversion by generating O2˙-, which resulted in a 6-fold enhanced photocurrent by using ascorbic acid as the O2 ˙- scavenger. Moreover, the inherent structural porosity of nPCN-224 demonstrated advantage for reactant accessibility. Due to the superior properties of nPCN-224, and the high specificity and affinity of Nbs, the immunosensor exhibited a broad detection range from 1.00 pg mL−1 to 10.0 ng mL−1 and a detection limit of 0.560 pg mL−1, lower than most methods reported before. The immunosensor could clearly distinguish ovarian cancer patients in different stages from healthy individuals, and the as-obtained results matched well with those by traditional electrochemiluminescence immunoassay method from the hospital. This work would open a new avenue for PEC immunosensors in clinical diagnostics and evaluation of potential clinical efficacy.