The Preparation Of Photoelectrochemical Immunosensors Based On Metal-Organic Framework Nanomaterials And The Application In Detection Of Tumor Markers

Ovarian cancer is one of the most popular malignant tumors for the female,which seriously threatens the life and health of women.Therefore,it is of great significance to realize the rapid and accurate quantification of ovarian cancer-related tumor markers for the early diagnosis and screening,timely treatment and efficacy monitoring.The photoelectrochemical（PEC）immunosensor has been widely used to detect different tumor markers due to its low cost,simple equipment,high sensitivity and excellent selectivity.This thesis mainly focuses on the preparation of functional nanoparticles,the mechanism of photocurrent generation,and the construction of new PEC immunosensors for accurate and sensitive detection of tumor markers.The details of the thesis are as follows:1.Porphyrin-based metal-organic framework（MOF）nanospheres（nPCN-224）were prepared by the hydrothermal method using carboxy-functionalized porphyrins（H₂TCPP）as organic ligands,with an average size of 160～200 nm.And the photocurrent intensity was about 3.5 times higher than that of its monomer H₂TCPP.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.2.A“signal-on”PEC immunosensor was constructed by combining n PCN-224and nanobody（Nb）for the detection of human epididymal protein 4（HE4）,a tumor marker of ovarian cancer with small molecular weight.Due to the excellent photoelectric performance of n PCN-224 and the high specificity and affinity of Nbs,the constructed immunosensor showed high stability,good selectivity,wide detection range(1.00 pg·m L^-1～10.0 ng·m L^-1)and low detection limit(0.560 pg·m L^-1)in the detection of HE4.In addition,the constructed immunosensor can accurately distinguish ovarian cancer patients from healthy individuals,and the 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.3.An enzyme-like MnO₂ NS was synthesized and its quenching effect on the photoelectric performance of nPCN-224 was investigated.It was found that Mn O₂ NS exhibited enzyme-like properties,which could catalyze 3,3’,5,5’-tetramethyl benzidine（TMB）,and catalyze the oxidation of 4-chloro-1-naphthol（4-CN）with precipitated product.As a result,Mn O₂ NS showed double quenching effect on the photoelectric signal of n PCN-224,due to the competitive absorption between the Mn O₂ NS and n PCN-224,and the catalytic oxidation of 4-CN into precipitates on the surface of nPCN-224.This work would pave a way for the further study of“signal-off”PEC immunosensing based on MnO₂ NS and nPCN-224.