The Photoelectrochemical Immunosensor Based On Photoelectric Semiconductor Material To Detect Carcinoembryonic Antigen

Malignant tumor（also known as cancer）,because of its biological characteristics such asabnormal cell differentiation and proliferation,uncontrolled growth,infiltration and metastasis,has become a major threat to human health and an important factor leading to death in recent years.The diagnosis,treatment and prognosis of cancer are closely related to the stage state of tumor,and the stage state of tumor is closely related to the content of tumor markers in human serum.Tumor markers are substances that exist in cancer cells,or are produced by abnormal cancer cells,or by the stress response of the host to the tumor,which can reflect the occurrence and development of the tumor and monitor the response of the tumor to treatment.Carcinoembryonic antigen（CEA）is a broad-spectrum tumor marker.The abnormal content of CEA is closely related to the occurrence and development of rectal cancer,gastric cancer,urinary tract cancer,ovarian cancer,lung cancer,pancreatic cancer,breast cancer,medullary thyroid cancer,bladder cancer and cervical cancer.Generally speaking,the earlier the patients get diagnosis and treatment,the better the prognosis,and the higher the survival rate.Therefore,the qualitative and quantitative detection of carcinoembryonic antigen in human serum is conducive to the timely detection,treatment and monitoring of cancer.The content of tumor markers in human serum is very low,and there are many kinds of antigens in human serum at the same time,so the analytical method is required to have good selectivity and high sensitivity,which can achieve the accurate and rapid detection of carcinoembryonic antigen.At present,photoelectrochemical immunoassay has become a research hotspot of immunoassay because of its advantages such as simple detection device,low cost,fast analysis speed and easy miniaturization.Photoelectric chemical immunoassay is mainly used to detect tumor markers by combining highly specific immunochemical reaction with physical analysis sensor.The excitation source（light source）and detection signal（current signal）of the photoelectric immune sensor are independent of each other,so it can greatly reduce the background interference and improve the detection sensitivity.The detection limit of tumor markers can be as low as 0.1pg/m L.carcinoembryonic antigenTo sum up,this paper has done the following research work:（1）An ultrasensitive photoelectrochemical（PEC）immunosensor for the detection of CEA was constructed using Cd Se@Bi VO₄co-sensitized Ti O₂nanorods as photoactive materials.Ti O₂nanorods were assembled on the FTO modified electrode to immobilize capture antibodies.With a sandwich immunoassay format,CEA and signal antibodies labelled Cd Se@Bi VO₄were introduced in sequence via specific immunoreaction,and the ultrahigh sensitivity of this immunoassay results from the following three aspects.Firstly,the co-sensitization of Bi VO₄and Cd Se extends the absorption range of Ti O₂from ultraviolet region to visible light region,which can adequately utilize the light energy;Secondly,the effective matching of energy levels among Ti O₂,Cd Se and Bi VO₄accelerates the separation and transfer of photogenerated electron-hole pairs and significantly improves the PEC performance;Finally,the introduced Au evidently expedites the interfacial electron transfer from Ti O₂to FTO electrode,further resulting in noticeably increased photocurrent.Based on multiple signal amplification strategy,a largely linear detection range from 0.01 ng m L^-1to50 ng m L^-1with a low detection limit(0.5 pg m L^-1)were obtained.In addition,the prepared immunosensor with attractive properties provides a promising platform for PEC detection.（2）Prepared ZnO@Fe₂O₃ As a substrate photoelectric material,a single-layer photoelectric immunosensor was constructed.Zn O was grown on FTO modified electrode by hydrothermal method,and then Fe₂O₃was prepared.Fe₂O₃and antibody antigen were assembled in turn,and the sensor was assembled by specific immunity.Fe₂O₃is a kind of high-performance photoelectric material with moderate band gap.Under all-optical irradiation,the photocurrent is large and stable,and the sensor can detect low concentration and high precision.The linear detection range of the sensor is from 0.005 ng/m L to 50 ng/m L,and the detection limit is（0.5pg/mL）.