| Human chorionic gonadotropin(hCG)is a kind of glycoprotein and divided into a and ?subunits,among the latter is able to show the hormone level,which is called ?-hCG.Not only does ?-hCG act as the most important diagnostic marker of gestation,but also as a marker of tumor.Therefore,the ability to quickly detect ?-hCG is of great value for pregnancy safety and early cancer screening.Immunodetection methods has the characteristics of high sensitivity and specificity of immunoassay.However,immunosensors combine traditional immunodetection and biosensing technologies,which has the advantages of both parties.For example,the analysis time is reduced,the accuracy is improved,and it is beneficial to Implementation of automation,etc.Consequently,the design and application of immunosensor provide new ideas for detection methods of ?-hCG.This paper combines surface Raman enhanced scattering effect(SERS)and electrochemical impedance technology to design an immunosensor that can be used for SERS and electrochemical detection,and attempts to use the sensor for ?-hCG detection research.The main research content includes the following parts:(1)A simple one-step method was used to construct a SERS substrate based on MXene/Ag composite nanomaterials;the probe molecules were methylene blue and p-mercaptobenzoic acid to explore and analyze the SERS activity of the substrate,and the screening improved the corresponding preparation condition.On this basis,an immunosensor for SERS detection was constructed using a magnetic substrate and an external magnetic field.The limit of detection of ?-hCG is 1.5 ×10-7 mIU mL-1.Among,between the concentration limits of 1.0 × 10-6 and 1.0 × 10-2 mIU mL-1,Raman signal intensity at 1583 cm-1 is linear correlated to the logarithm of ?-hCG concentration(R=0.9952).This immunosensor,used for quantitative determination of ?-hCG in serum,compared to the Roche electrochemiluminescence,reduces the relative error value to less than 10%,while specificity result RSD less than 4%.(2)MXene/Ag creates an electronicchemical impedance immunosensor,which plays a role of signal amplification.The rapid assay of ?-hCG can be realized by modifying MXene/Ag composite nanomaterials on the surface of glassy carbon electrode,fixing antibody,and recording the variation of electrochemical impedance caused by the specific immune response between ?-hCG antigen and antibody.According to the experiment,the limit of detection of this immunosensor is up to 5.0 × 10-3 mIU mL-1,and the logarithm of the antigen concentration is in the range of 1.0 × 10-2 to 1.0 × 102 mIU ML-1,which has a relatively good linear relationship.With the characteristics of simple construction method,high sensitivity,good reproducibility and stability,the rapid detection of ?-hCG in serum sample can be realized by the above immunosensor.(3)Based on the 3D printing technology,the electrochemical cell is designed,and the conductive glass is used as the working electrode to construct a portable impedance immunosensor test technology.The antibody is adsorbed by magnetic beads combined with streptavidin,and the magnetic beads and the antibody complex are fixed on the integrated immunosensor by an external magnetic field.Under the best conditions,the relative change of AC impedance and the logarithm of ?-hCG antigen concentration are linearly related within the range of 1.0 × 10-1?1.0 × 103mIU mL-1(R=0.9988),and the detection limit is 5.0×10-2 mIU mL-1.The impedance-type immune sensor can be used for quantitative detection of human serum ?-hCG based on the electrochemical principle,which makes the method have the advantages of low cost,simple operation,and portable detection. |
PDF Full Text Request