Application Of Colorimetric Immunosensor Based On Silver Nanomaterials In CEA Detection

It is well-known that malignant tumors have become the major killer of human beings.Early diagnosis and early treatment are the most effective measures to prevent cancer and reduce mortality.Carcinoembryonic antigen?CEA?can reflect the existence of a variety of tumors to people as a broad spectrum of tumor markers,which has great value for medical research and clinical diagnosis.Due to their good photocatalytic properties and the strong oxidizing properties of silver ions hydrolyzed by some silver-based nanomaterials,which make it possible to construct novel colorimetric immunosensors.In this paper,I have built a colorimetric immunosensor for the detection of CEA antigens using three representative silver-based nanocomposites Ag₃PO₄/Ag,Cu²⁺/Ag-AgI and Ag I/ZnO.The main contents and results are as follows:?1?Ag₃PO₄/Ag nanoparticles were prepared by the thermal reflow method using ethylene glycol?EG?as solvent and Na₂HPO₄·12H₂O and AgNO₃ as raw materials.Furthermore,a colorimetric immunosensing system consisting of the immunos sandwich structure of antibody-antigen-antibody and TMB was constructed,and The Ag⁺catalyzed TMB colorization of Ag₃PO₄ hydrolyzed under acidic conditions.The results showed that under the optimum reaction conditions,the UV absorbance of color developed with the increase of CEA concentration,the linear range of detection was 0.2 ng/mL-2.5 ng/mL,and the lowest detection limit was 0.03 ng/mL.The colorimetric sensor preparation method is simple and does not require the participation of H₂O₂ and the reaction is rapid.?2?Ag-AgI nanocomposites were prepared by precipitation method,then Cu²⁺attached to the surface of the material to obtain Cu²⁺/Ag-AgI nanocomposite system.Under visible light irradiation,Cu²⁺on the surface of Ag-AgI accelerates the photogenerated electron transfer and further enhances the photocatalytic activity.The experimental results showed that the colorimetric immunosensor composed of such nanocomposites had a broader range and more sensitivity for detecting CEA antigens,the lowest detection limit reached 0.13 pg/mL.?3?The AgI/ZnO nanocomposites were prepared by precipitation method,then chitosan?CS?was modified on the surface of nanoparticles to further construct a colorimetric immunosensor.Based on the unique photocatalytic properties of Ag I and ZnO,the chromogenic substrate TMB was catalytically oxidized.It has been experimentally confirmed that the catalytic coloration mechanism is due to the fact that photo-generated holes are at work.Under the optimum reaction conditions,the linear range of CEA for detection was 0.01ng/mL-40 ng/mL and the detection limit was 18 pg/mL.And the colorimetric sensor had good stability and specificity.