Construction Of Photoelectrochemical Biosensor Based On Functional Nanomaterials For Detection Of Carcinoembryonic Antige

The detection of tumor markers is of great significance for screening high-risk populations for cancer,assisting diagnosis,evaluating treatment effectiveness,monitoring postoperative recurrence,and predicting prognosis.As a powerful analysis method for tumor marker,photoelectrochemical（PEC）biosensing has advantages such as high selectivity,short detection time,and miniaturization of instruments.By utilizing the specific recognition between tumor markers and probes for different recognition elements,the photoelectrochemical biosensors can achieve high specificity and sensitivity for the detection of tumor markers.In addition,new nanomaterials and signal amplification strategies provide new ideas for the design of biosensors.Based on the above,this paper combines functional nanomaterials and signal amplification technology to explore new detection modes and signal transduction mechanisms,as well as constructs several new photoelectrochemical biosensors with high sensitivity for the detection of carcinoembryonic（CEA）antigens.The main research contents of this thesis are as follows:1.In this work,a multimodal biosensor based on three-dimensional hollow Cd S@Au nanospheres and target-induced ion exchange technology was constructed for carcinoembryonic antigen（CEA）detection.A 3D hollow HCd S@Au nanosphere synthesized by the templated-assisted method and photodeposition is employed to construct a multimodal sensing platform by combining the photoelectrochemical（PEC）biosensor with colorimetric analysis and photothermal imaging.In the presence of target carcinoembryonic antigen（CEA）,a sandwich structure is formed on magnetic beads based on the dual-aptamer recognition,followed by the initiation of rolling circle amplification（RCA）to bind numerous Cu O-DNA probes.Upon stimulation by hydr chloric acidic,a large number of Cu2+ is released from Cu O,which could interact with yellow HCd S@Au on electrode to produce dark Cu S by ion exchange.This work exhibits an excellent performance for sensitive and selective detection of CEA in the dynamic working range from 0.015 to 2.4 ng/m L with a detection limit as low as 3.5 pg/m L.Moreover,the proposed PEC biosensor is successfully applied to CEA determination in human serum,which holds great promise in accurate analysis of biomarkers and early diagnosis of diseases in the clinic.2.In this work,a ratiometric PEC biosensor was constructed based on the shape controllable CeO₂ peroxidase and the dual channel electrode.The sensitive detection of CEA was realized based on the ratio of the output signal（Iw/Ic）of the working electrode and the internal reference electrode,which effectively reduced the impact of the external environment on the photocurrent signal,and improved the detection sensitivity.The dualchannel electrodes of the PEC biosensor are modified with CeO₂/Cd S.An immune sandwich structure is formed based on a dual antibody recognition strategy after introducing CEA.The GOx/CeO₂ catalytic system was constructed by using the peroxidase-like properties of CeO₂,in which the H2O2 generated from the catalysis of glucose by GOx could be catalyzed by CeO₂ to produce ·OH.The ·OH etched the Cd S on the surface of CeO₂,resulting in the reduction of the photocurrent of the working electrode.Quantitative analysis of CEA was realized based on Iw/Ic.In addition,based on 3D printing technology,the photoelectric detection devices of this PEC biosensor achieves portable and miniaturized detection.This portable PEC biosensor exhibits good response to CEA in the range of 0.1-10.0 ng/m L with a detection limit of 0.057 ng/m L.Furthermore,this biosensor shows satisfactory accuracy,selectivity and stability,and possesses good application prospects.