Immunoelectrochemical Sensor For Detection Of Human Chorionic Gonadotropin Based On Nanomaterials

Human chorionic gonadotropin（HCG）is a type of hormone composed of two subunitsαandβHeterodimeric glycoprotein hormones composed of.It is produced by placental trophoblast cells and can excrete urine through maternal blood circulation.Electrochemical analysis has unique advantages,such as high sensitivity and selectivity,low cost,fast response,easy operation,and miniaturization.This paper constructs an immunosensor based on synergistic signal amplification to detect human chorionic gonadotropin.The immunosensor uses Fe（CN）₆^3-/4-and pyrrole as electrochemical signal probes,gold nanoparticles and melamine as signal amplification elements,screen printed carbon electrode（SPCE）as substrate,and is assembled layer by layer.HCG antibody（Anti-HCG）and BSA are successively fixed on the surface of the modified electrode,and BSA blocks the non-specific active site of the immunosensor.Two electrochemical immunosensors were constructed:BSA/Anti-HCG/c-AuNPs/Mel/e-AuNPs/SPCE（two different sizes of AuNPs,e-AuNPs being electrochemically deposited AuNPs and c-AuNPs being generated by the chemical reduction method of trisodium citrate）and BSA/Anti-HCG/Pyrole/e-AuNPs/SPCE,achieving quantitative detection of HCG within a certain range.The main research content is as follows:（1）The BSA/Anti-HCG/c-AuNPs/Mel/e-AuNPs/SPCE immunosensor was constructed.With Fe（CN）₆^3-/4-as the electrochemical signal probe,AuNPs and Mel co-amplified the electrochemical signal,with the oxidation potential range of 0.2～0.3 V.The peak value of the response current of Mel/e-AuNPs/SPCE in the DPV diagram was twice that of e-AuNPs/SPCE.The construction process of the immunosensor was characterized by SEM,EDS and CV methods,and various factors affecting the electrochemical performance of the sensor were studied,and the relevant parameters affecting the sensor were optimized.The immunosensor shows a good linear relationship in the HCG concentration range of 0.1～500.0 pg?m L^-1.Through linear fitting,the linear equation can be obtained:I=12.1460-2.2793lg（c）(I is the current value,μA,c is the HCG concentration,pg?m L^-1),the correlation coefficient is 0.9948,the lowest detection line is 0.056 pg?m L^-1,and the sensitivity is 32.245μA?pg^-1?m L?cm^-2.By studying the selectivity,stability and reproducibility of the sensor,it is proved that the sensor has good selectivity,stability and reproducibility.The immunosensor detects the actual sample serum by standard addition method.The concentration of HCG spiked is 1.0,10.0 and100.0 pg?m L^-1,respectively.The RSD of the determination result is 0.634～1.955%,and the recovery range is 103.24～105.58%.The result shows that the immunosensor has a good recovery rate and can be applied to the detection of actual serum samples.（2）The BSA/Anti-HCG/pyrrole/e-AuNPs/SPCE immunosensor was constructed,with pyrrole as the electrochemical signal probe and AuNPs as the signal amplification element.Its oxidation potential range was about 0.8 V.The peak value of the response current of pyrrole/e-AuNPs/SPCE in the DPV diagram was 1.7 times that of e-AuNPs/SPCE.The construction process of the immunosensor was characterized by SEM,EDS and CV methods,and various factors affecting the electrochemical performance of the sensor were studied,and the relevant parameters affecting the sensor were optimized.The immunosensor shows a good linear relationship in the HCG concentration range of 40～5000 fg?m L^-1.Through linear fitting,the linear equation can be obtained:I=8.86377-1.1141lg（c）(I is the current value,μA,c is the HCG concentration,fg?m L^-1),the correlation coefficient is 0.9918,the lowest detection line is16.53 fg?m L^-1,and the sensitivity is 15.76μA?pg^-1?m L?cm^-2.By studying the selectivity,stability and reproducibility of the sensor,it is proved that the sensor has good selectivity,stability and reproducibility.The epidemic sensor detects the actual sample serum by standard addition method.The concentration of HCG spiked is 200,500 and 2000fg?m L^-1,respectively.The RSD of the determination result is 0.573～1.301%,and the recovery range is 96.0～117.4%.The result shows that the immune sensor has a good recovery rate,which can be applied to the detection of actual serum samples.（3）The signal probe of BSA/Anti-HCG/c-AuNPs/Mel/e-AuNPs/SPCE is Fe（CN）₆^3-/4-,and the signal probe of BSA/Anti-HCG/pyrrole/e-AuNPs/SPCE is pyrrole.Compared with the two immunosensors,the second sensor has a lower detection line than the first sensor,and the manufacturing steps are simpler.The detection range of the two sensors can complement each other to achieve a wider range of HCG detection.Both immunosensors can be applied to the detection of actual serum samples.