Research On Copper-based Nanomaterials In Electrochemical Immunosensors

As a typical tumor marker,carcinoembryonic antigen（CEA）plays an important role in the screening and diagnosis of colorectal cancer,lung cancer,breast cancer and other cancers.Currently,the development of analytical techniques for the detection of CEA has become a hot topic of research worldwide.Electrochemical immunosensors have the advantages of high sensitivity,good specificity,and strong selectivity,and are widely used in the detection of various tumor markers.Copper-based nanomaterials have broad application prospects in biosensing due to their excellent catalytic activity.Therefore,the preparation of copper-based nanomaterials with high catalytic activity is conducive to the realization of high-sensitivity detection of CEA.This thesis aims to improve the sensitivity of electrochemical immunosensors and reduce the errors caused by the introduction of exogenous substances,and constructs electrochemical immunosensors based on copper-based nanomaterials with multiple signaling strategies to achieve highly sensitive detection of CEA.The main research work is as follows:1.An electrochemical immunosensor based on Cu Co/CNC was constructed for the detection of CEA.Cu Co/CNC has a large specific surface area and excellent electrocatalytic reduction ability for hydrogen peroxide（H₂O₂）.Au/g-C₃N₄ nanosheets（Au/g-C₃N₄ NSs）were modified to the immunological platform,and more capture antibodies（Ab₁）could be attached.In addition,the response current value was positively correlated with the CEA antigen concentration.The prepared electrochemical immunosensor has excellent detection performance.The sensor has a detection range of 0.0001 ng/m L-80 ng/m L with a detection limit of0.031 pg/m L（S/N=3）.2.Combining the high sensitivity of electrochemical analysis technology with the rapidity of colorimetric analysis technology,a device for accurate detection of CEA in dual modes was prepared.cuprous oxide/platinum nanoparticles（Cu₂O/Pt NPs）have excellent peroxidase activity and can not only generate a large response signal in electrochemical mode as a signal tag,but also catalyze in colorimetric mode 3,3’,5,5’-Tetramethylbenzidine（TMB）color.The results show that the dual-mode sensor has good detection performance.Electrochemical analysis was used with a detection range of 0.1 pg/m L-80 ng/m L and a detection limit of 0.03 pg/m L.The detection range of colorimetric analysis technology is 0.1 ng/m L-80ng/m L,and the detection limit is 0.026 ng/m L（S/N=3）.3.An electrochemical immunosensor with a"signal on"strategy was engineered for the purpose of CEA detection.The strategy is on the following basis:HMSNs-Cu²⁺@HA is used as the signal probe,hyaluronic acid（HA）is attacked under acidic environment,and the published Cu²⁺activated the peroxidase activity of the electrode base MMo O₄（M=Co,Ni）,which results in the electrical signal turn-on.This approach has the next benefits:（1）HA-coated HMSNs-Cu²⁺protects against Cu²⁺leakage,and HA has excellent biosynthesis and can be linked to a larger number of detection antibodies（Ab₂）;（2）The obtained sensor has the advantages of higher sensitivity and low cost.when the immunoplatform of the electrode was Co Mo O₄ with a detection range of 0.01 pg/m L-40 ng/m L,The limits of detection were 0.0035 pg/m L（S/N=3）.4.An electrochemical immunosensor with a dual signal attenuation strategy was conceived for the assay of CEA.The sensor uses Prussian blue nanoparticles（PB NPs）as an immune platform.At acidic conditions,Cu O₂@Si O₂can release Cu²⁺and H₂O₂,and the freed Cu²⁺can replace the high-spin iron(Fe ^III)in PB NPs.The self-generated H₂O₂ can react with PB NPs and 4-CN to form insoluble precipitates on the electrode,thus gradually reducing the electrochemical signal of PB NPs.Square wave voltammetry（SWV）analysis showed that with the detection of different CEA antigen concentrations,the oxidation peak signal of PB NPs changes.The results showed that the immunosensor had a good calibration linearity in the range of 0.01pg/m L-80 ng/m L,with a detection limit of 0.0032 pg/m L（S/N=3）.